Note: Descriptions are shown in the official language in which they were submitted.
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NOVEL CLEANING PROCESS USING CARBON DIOXIDE
AS A SOLVENT AND EMPLOYING MOLECULARLY
' ENGINEERED SURFACTANTS
Fief? r~f the Invention
The present invention relates to a method of
cleaning a contaminant from a substrate, and more
particularly, to a method of cleaning a contaminant
from a substrate using carbon dioxide and an
amphiphilic species contained therein.
Backctround of the Invention
In numerous industrial applications, it is
desirable to sufficiently remove different
contaminants from various metal, polymeric, ceramic,
composite, glass, and natural material substrates such
as those contai:.ing textiles . I t is of ten re.~,~ired
that the level of contaminant removal be sufficient
such that the substrate can be subsequently used in an
acceptable manner. Industrial contaminants which are
typically removed include organic compounds (e. g., oi:L,
grease, and polymers), inorganic compounds, and ionic
compounds (e. g., salts).
In the past, halogenated solvents have been
used to remove contaminants from various substrates
and, in particular, chlorofluorocarbons have been
employed. The use of such solvents, however, has been
disfavored due to the associated environmental risks.
Moreover, employing less volatile solvents (e. g.,
aqueous solvents) as a replacement to the halogenated
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solvents may be disadvantageous, since extensive post-
cleaning drying of the cleaned substrate is often
required. ~ .
As an alternative, carbon dioxide has been
~5 proposed to carry out contaminant removal, since the
carbon dioxide poses reduced environmental risks. U.S.
Patent No. 5,316,591 proposes using liquefied carbon
dioxide to remove contaminants such as oil and grease
from various substrate surfaces. Moreover, the use of
l0 carbon dioxide in conjunction with a co-solvent has
also been reported in attempt to remove materials which
possess limited solubility in carbon dioxide. For
example, U.3. ratent Nos. 5,306,350 and 5,377,705
propose employing supercritical carbon dioxide with
15 various organic co-solvents to remove primarily organi~~
contaminants.
In spite of the increased ability to remove
contaminants which have limited solubility in carbon
dioxide, there remains a need for carbon dioxide to
20 remove a wide range of organic and inorganic materials
such as high molecular weight non-polar and polar
compounds, along with ionic compounds. Moreover, it
would be desirable to remove these materials using more'
environmentally-acceptable additives in conjunction
25 with carbon dioxide.
It is an object of an aspect of the present invention to provide a process
for separating a wide range of contaminants from a substrate which does not
require
organic solvents.
3 0 Summary of the Invention
The present invention includes a process for separating a contaminant
from a substrate that carnes the contaminant. Specifically, the process
comprises
contacting the substrate to a carbon dioxide fluid containing an amphiphilic
species s;o
that the contaminant associates with the amphiphilic species and becomes
entrained iin
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the carbon dioxide fluid. The process may further comprise separating the
substrate
from the carbon dioxide fluid having the contaminant entrained therein, and
then
separating the contaminant from the carbon dioxide fluid.
The carbon dioxide fluid may be present in the supercritical, gaseous,
or liquid phase. Preferably, the amphiphilic species employed in the carbon
dioxide
phase comprises a "COZ-philic" segment which has an affinity for the COz. More
preferably, the amphiphilic species further comprises a "C02-phobic" segment
which
does not have an affinity for the CO2.
Various substrates may be cleaned in accordance with the invention.
Exemplary substrates include polymers, metals, ceramics, glass, and composite
mixtures thereof. Contaminats that may be separated from the substrate are
numerous
and include, for example, inorganic compounds, organic compounds, polymers,
and
particulate matter.
In accordance with one embodiment, a process for separating a
contaminant from a substrate selected from the group consisting of polymers,
metals,
ceramics, glass, and composite mixtures thereof, which comprises:
(i) contacting the substrate with a pressurized fluid comprising carbon
dioxide as
a continuous phase, said carbon dioxide continuous phase comprising an
amphiphilic species comprising a C02-philic segment covalently joined to a
COZ-phobic segment so that the contaminant associates with the amphiphilic:
species and becomes entrained in the fluid;
(ii) separating the substrate from the fluid having the contaminant entrained
therein; and
(iii) separating the contaminant from the fluid.
Detailed Description of the Preferred Embodiments
The present invention is directed to a process for separating a
contaminant from a substrate that carries the contaminant. Specifically, the
process
comprises contacting the substrate to a carbon dioxide fluid which contains an
amphiphilic species. As a result, the contaminant associates with the
amphiphilic
species and becomes entrained in the carbon dioxide fluid. The process also
comprises separating the substrate from the carbon dioxide fluid having the
contaminant entrained therein, and then separating the contaminant from the
carbon
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dioxide fluid. For the purposes of the invention, carbon dioxide is employed
as a
fluid in a liquid, gaseous, or supercritical phase. If liquid C02 is used, the
temperature employed during the process is preferably
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below 31°C. If gaseous C02 is used, it is preferred
that the phase be employed at high pressure. As used
herein, the term "high pressure" generally refers.to COZ
having a pressure from about 20 to about 73 bar. In
the preferred embodiment, the C02 is utilized in a
"supercritical" phase. As used herein, "supercritical"
means that a fluid medium is at a temperature that is
sufficiently high that it cannot be liquified by
pressure. The thermodynamic properties of C02 are
reported in Hyatt, J. Org. Chem. 49: 5097-5101 (1984?;
therein, it is stated that the critical temperature of
COz is about 31°C; thus the method of the present
invention should be carried out at a temperature above
31°.
The C02 fluid used in cleaning applications
can be employed in a single or multi-phase system with
appropriate and known aqueous and organic liquid
components. Such components generally include a co-
solvent or modifier, a co-surfactant, and other
additives such as bleaches, optical brighteners,
enzymes, rheology modifiers, sequestering agents, and
chelants. Any or all ofthe components may be employed
in the COa-based cleaning process of the present
invention prior to, during, or after the substrate is
contacted by the COz fluid.
In particular, a co-solvent or modifier is a
component of a COZ-based cleaning formulation that is
believed to modify the bulk solvent properties of the
medium to which it is added. Advantageously, the use
of the co-solvents in low polarity compressible fluids
such as carbon dioxide have been observed to have a
dramatic effect on the solvency of the fluid medium. '
In general, two types of co-solvents or modifiers may
be employed, namely one which is miscible with the C02 '
fluid and one that is not miscible with the fluid.
When a co-solvent is employed which is miscible with
the C02 fluid, a single-phase solution results. When a
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co-solvent is employed which is not miscible with the
COa fluid, a multi-phase system results. Examples of
suitable co-solvents or modifiers include, but are not
limited to, liquid solvents such as water and aqueous
solutions which may contain various appropriate water-
soluble solutes. For the purposes of the invention, an
aqueous solution may be present in amounts so as to be
miscible in the COZ-phase, or may be present in other
amounts so as to be considered immiscible with the COZ-
phase. The term "aqueous solution" should be broadly
construed to include water and other appropriate water-
soluble components. The water may be being of various
appropriate grades such as tap water or purified water,
for example.
Exemplary solutes which may be used as co-
solvents include, but are not limited to, alcohols
(e. g., methanol, ethanol, and isopropanol); fluorinated
and other halogenated solvents (e. g., chlorotri-
fluoromethane, trichlorofluoromethane,
perfluoropropane, chlorodifluoromethane, and sulfur
hexafluoride); amines (e. g., N-methyl pyrrolidone);
amides (e. g., dimethyl acetamide); aromatic solvents
(e. g., benzene, toluene, and xylenes); esters (e. g.,
ethyl acetate, dibasic esters, and lactate esters);
ethers (e.g., diethyl ether, tetrahydrofuran, and
glycol ethers); aliphatic hydrocarbons (e. g., methane,
ethane, propane, ammonium butane, n-pentane, and
hexanes); oxides (e. g., nitrous oxide); olefins (e. g.,
ethylene and propylene); natural hydrocarbons (e. g.,
isoprenes, terpenes, and d-limonene); ketones (e. g.,
acetone and methyl ethyl ketone); organosilicones;
alkyl pyrrolidones (e. g., N-methyl pyrrolidone);
paraffins (e. g., isoparaffin); petroleum-based solvents
- and solvent mixtures; and any other compatible solvent
or mixture that is available and suitable. Mixtures of
the above co-solvents may be used. The co-solvent or
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modifier can be used prior to, during, or after the
substrate is contacted by the C02 fluid.
The process of the present invention employs ,
an amphiphilic species contained within the carbon
dioxide fluid. The amphiphilic species should be one
that is surface active in the COa fluid and thus creates
a dispersed phase of matter which would otherwise
exhibit low solubility in the carbon dioxide fluid.
In general, the amphiphilic species partitions between
the contaminant and the C02 phase and thus lowers the
interfacial tension between the two components, thus
promoting the entrainment of the contaminant in the COZ
phase. The amphiphilic species is generally present in
the carbon dioxide fluid from 0.001 to 30 weight
percent. It is preferred that the amphiphilic species
contain a segment which has an affinity for the C02
phase ("C02-philic"). More preferably, the amphiphilic
species also contains a segment which does not have an
affinity for the COZ-phase ( "COZ-phobic" ) and may be
covalently joined to the COa-philic segment.
Exemplary C02-philic segments may include a
fluorine-containing segment or a siloxane-containing
segment. The fluorine-containing segment is typically
a "fluoropolymer". As used herein, a "fluoropolymer"
has its conventional meaning in the art and should also
be understood to include low molecular weight
oligomers, i.e., those which have a degree of
polymerization greater than or equal to two. See
generally Banks et al., Organofluorine Compounds:
Principals and Applications (1994); see also Fluorine-
Containing Polymers, 7 Encyclopedia of Polymer Science
and Engineering 256 (H. Mark et al. Eds. 2d Ed. 1985).
Exemplary fluoropolymers are formed from monomers which
may include fluoroacrylate monomers such as 2-(N-
ethylperfluorooctanesulfonamido) ethyl acrylate
("EtFOSEA"), 2-(N-ethylperfluorooctanesulfonamido)
ethyl methacrylate ("EtFOSEMA"), 2-(N-
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methylperfluorooctanesulfonamido) ethyl acrylate
("MeFOSEA"), 2-(N-methylperfluorooctanesulfonamido)
ethyl methacrylate ("MeFOSEMA"), 1,1'-
dihydroperfluorooctyl acrylate ("FOA"), 1,1'-
dihydroperfluorooctyl methacrylate ("FOMA"), 1,1',2,2'-
tetrahydroperfluoroalkylacrylate, 1,1',2,2'-tetrahydro
perfluoroalkylmethacrylate and other
fluoromethacrylates; fluorostyrene monomers such as a-
fluorostyrene and 2,4,6-trifluoromethylstyrene;
fluoroalkylene oxide monomers such as
hexafluoropropylene oxide and perfluorocyclohexane
oxide; fluoroolefins such as tetrafluoroethylene,
vinylidine fluoride, and chlorotrifluoroethylene; and
fluorinated alkyl vinyl ether monomers such as
perfluoro(propyl vinyl ether) and perfluoro(methyl
vinyl ether). Copolymers using the above monomers may
. also be employed. Exemplary siloxane-containing
segments include alkyl, fluoroalkyl, and chloroalkyl
siloxanes. More specifically, dimethyl siloxanes and
polydimethylsiloxane materials are useful. Mixtures of
any of the above may be used.
Exemplary COa-phobic segments may comprise
common lipophilic, oleophilic, and aromatic polymers,
as well as oligomers formed from monomers such as
ethylene, a-olefins, styrenics, acrylates,
methacrylates, ethylene and propylene oxides,
isobutylene, vinyl alcohols, acrylic acid, methacrylic
acid, and vinyl pyrrolidone. The C02-phobic segment may
also comprise molecular units containing various
functional groups such as amides; esters; sulfones;
sulfonamides; imides; thiols; alcohols; dimes; diols;
acids such as carboxylic, sulfonic, and phosphoric;
salts of various acids; ethers; ketones; cyanos;
- amines; quaternary ammonium salts; and thiozoles.
Amphiphilic species which are suitable for
the invention may be in the form of, for example,
random, block (e. g., di-block, tri-block, or multi-
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block), blocky (those from step growth polymerization),
and star homopolymers, copolymers, and co-oligomers.
Exemplary block copolymers include, but are not limited ,
to, polystyrene-b-poly(1,1-dihydroperfluorooctyl
acrylate), polymethyl methacrylate-b-poly(1,1-
dihydroperfluorooctyl methacrylate), poly(2-
(dimethylamino)ethyl methacrylate)-b-poly(1,1-
dihydroperfluorooctyl methacrylate), and a diblock
copolymer of poly(2-hydroxyethyl methacrylate) and
poly(1,1-dihydroperfluorooctyl methacrylate).
Statistical copolymers of poly(1,1-dihydroperfluoro
octyl acrylate) and polystyrene, along with poly(1,1-
dihydroperfluorooctyl methacrylate) and poly(2-
hydroxyethyl methacrylate) can also be used. Graft
copolymers may be also be used and include, for
example, poly(styrene-g-dimethylsiloxane), poly(methyl
acrylate-g-1,1'dihydroperfluorooctyl methacrylate), and
poly(1,1'-dihydroperfluorooctyl acrylate-g-styrene).
Other examples can be found in I. Piirma, Polymeric
Surfactants (Marcel Dekker 1992); and G. Odian,
Principals of Polymerization (~Tohn Wiley and Sons, Inc.
1991). It should be emphasized that non-polymeric
molecules may be used such as perfluoro octanoic acid,
perfluoro(2-propoxy propanoic) acid, fluorinated
alcohols and diols, along with various fluorinated
acids, ethoxylates, amides, glycosides, alkanolamides,
quaternary ammonium salts, amine oxides, and amines.
Mixtures of any of the above may be used. Various
components which are suitable for the process of the
invention are encompassed by the class of materials
described in E. Kissa, Fluorinated Surfactants:
Synthesis, Properties, and Applications (Marcel Dekker °
1994) and K.R. Lange Detergents and Cleaners: A
HandbooJs for Formulators (Hanser Publishers 1994). For
the purposes of the invention, two or more amphiphilic
species may be employed in the COZ phase.
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A co-surfactant may be used in the C02 phase
in addition to the amphiphilic species. Suitable co-
surfactants are those materials which typically modify
the action of the amphiphilic species, for example, to
facilitate the transport of contaminant molecules or
material into or out of aggregates of the amphiphilic
species. Exemplary co-surfactants that may be used
include, but are not limited to, longer chain alcohols
(i.e., greater than CB) such as octanol, decanol,
dodecanol, cetyl, laurel,, and the like; and species
containing two or more alcohol groups or other hydrogen
bonding functionalities; amides; amines; and other like
components. An example of a typical application is the
use of cetyl alcohol as a co-surfactant in aqueous
systems such as in the mini-emulsion polymerization of
styrene using sodium lauryl sulfate as a surface active
component. Suitable other types of materials that are
useful as co-surfactants are well known by those
skilled in the art, and may be employed in the process
of the present invention. Mixtures of the above may
be used.
Other additives may be employed in the carbon
dioxide, preferably enhancing the physical or chemical
properties of the carbon dioxide fluid to promote
association of the amphiphilic species with the
contaminant and entrainment of the contaminant in the
fluid. The additives may also modify or promote the
action of the carbon dioxide fluid on a substrate.
Such additives may include, but are not limited to,
bleaching agents, optical brighteners, bleach
activators, corrosion inhibitors, enzymes, builders,
co-builders, chelants, sequestering agents, rheology
modifiers, and non-surface active polymeric materials
which prevent particle redeposition. Mixtures of any
of the above may be used. As an example, rheology
modifiers are those components which may increase the
viscosity of the C02 phase to facilitate contaminant
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removal. Exemplary polymers include, for example,
perfluoropolyethers, fluoroalkyl polyacrylics, and
siloxane oils. Additionally, other molecules may be
employed including C1-Clo alcohols, Cl-C1o branched or
straight-chained saturated or unsaturated hydrocarbons,
ketones, carboxylic acids, N-methyl pyrrolidone,
dimethylacetyamide, ethers, fluorocarbon solvents, and
chlorofluorocarbon solvents. For the purposes of the
invention, the additives are typically utilized up to
their solubility limit in the COz fluid employed during
the separation.
For the purposes of the invention, the term
"cleaning" should be understood to be consistent with
its conventional meaning in the art. Specifically,
"cleaning" should encompass all aspects of surface
treatment which are inherent in such processes. For
example, in the cleaning of garments, the use of
cationic surface active agents leads to their
adsorption on the fibers in the textile fabric which
reduces static electricity in the clothing that is
cleaned. Although the adsorption might not be
technically referred to as cleaning, Applicants believe
that such phenomena are typically inherent in a vast
majority of cleaning processes. Other examples include
the use of low levels of fluorinated surface active
agents in some aqueous systems for metal cleaning, the
adsorption of which creates desirable surface
properties in subsequent manufacturing steps, as well
as the use of fabric softeners in fabric care
formulations, the chemical action of bleaching agents
on surfaces, or the protective stain resistant action
imparted to surfaces by the use of silicone,
fluorinated, or other low surface energy components in
a cleaning or surface treatment formulation.
The process of the invention can be utilized
in a number of industrial applications. Exemplary
industrial applications include the cleaning of
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substrates utilized in metal forming and machining
processes; coating processes; fiber manufacturing and
processing; fire restoration; foundry applications;
garment care; recycling processes; surgical
implantation processes; high vacuum processes (e. g.,
optics); precision part cleaning and recycling
processes which employ, for example, gyroscopes, laser
guidance components and environmental equipment;
biomolecule and purification processes; food and
pharmaceutical processes; and microelectronic
maintenance and fabrication processes. Processes
relating to cleaning textile materials may also be
encompassed including those, for example, which pertain
to residential, commercial, and industrial cleaning of
clothes, fabrics, and other natural and synthetic
textile and textile-containing materials. Specific
processes can relate to cleaning of materials typically
carried out by conventional agitation machines using
aqueous-based solutions. Additionally, processes of
the invention can be employed in lieu of, or in
combination with, dry cleaning techniques.
The substrates which are employed for the
purposes of the invention are numerous and generally
include all suitable materials capable of being
cleaned. Exemplary substrates include porous and non-
porous solids such as metals, glass, ceramics,
synthetic and natural organic polymers, synthetic and
natural inorganic polymers, composites, and other
natural materials. Textile materials may also be
cleaning according to the process of the invention.
Various liquids and gel-like substances may also be
- employed as substrates and include, for example,
biomass, food products, and pharmaceutical. Mixtures
of solids and liquids can also be utilized including
various slurries, emulsions, and fluidized beds.
In general, the contaminants may encompass
materials such as inorganic compounds, organic
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compounds which includes polar and non-polar compounds,
polymers, oligomers, particulate matter, as well as
other materials. Inorganic and organic compounds.may ,
be interpreted to encompass oils as well as all
compounds. The contaminant may be isolated from the C02
and amphiphilic species to be utilized in further
downstream operations. Specific examples of the
contaminants include greases; salts; contaminated
aqueous solutions which may contain aqueous
contaminants; lubricants; human residues such as
fingerprints, body oils, and cosmetics; photoresists;
pharmaceutical compounds; food products such as flavors
and nutrients; dust; dirt; and residues generated from
exposure to the environment.
The steps involved in the process of the
present invention can be carried out using apparatus
and conditions known to those who are skilled in the
art. Typically, the process begins by providing a
substrate with a contaminant carried thereon in an
appropriate high pressure vessel. The amphiphilic
species is then typically introduced into the vessel.
Carbon dioxide fluid is usually then added to the
vessel and then the vessel is heated and pressurized.
Alternatively, the carbon dioxide and the amphiphilic
species may be introduced into the vessel
simultaneously. Additives (e.g., co-solvents, co-
surfactants and the like) may be added at an
appropriate time. Upon charging the vessel with COa,
the amphiphilic species becomes contained in the CO2.
The CO2 fluid then contacts the substrate and the
contaminant associates with the amphiphilic species and
becomes entrained in the fluid. During this time, the
vessel is preferably agitated by known techniques
including, for example, mechanical agitation; sonic,
gas, or liquid jet agitation; pressure pulsing; or any
other suitable mixing technique. Depending on the
conditions employed in the separation process, varying
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portions of the contaminant may be removed from the
substrate, ranging from relatively small amounts to
nearly all of the contaminant.
The substrate is then separated from the C02
fluid by any suitable method, such as by purging or
releasing the C02 for example. Subsequently, the
contaminant is separated from the C02 fluid. Any known
technique may be employed for this step; preferably,
temperature and pressure profiling of the fluid is
employed to vary the solubility of the contaminant in
the CO2 such that it separates out of the fluid. In
addition, the same technique may be used to separate
the amphiphilic species from the C02 fluid.
Additionally, a co-solvent, co-surfactant, or any other
additive material can be separated. Any of the
materials may be recycled for subsequent use in
accordance with known methods. For example, the
temperature and pressure of the vessel may be varied to
facilitate removal of residual surfactant from the
substrate being cleaned.
In addition to the steps for separating the
contaminant described above, additional steps may be
employed in the present invention. For example, prior
to contacting the substrate with the COZ fluid, the
substrate may be contacted with a pre-treatment
formulation to facilitate subsequent removal of the
contaminant from the substrate. For the purposes of
the invention, the term "pre-treatment formulation"
refers to an appropriate solvent, surface treatment,
chemical agent, additive, or mixture thereof including,
but not limited to, those recited herein. For example,
- a basic or acidic pre-treatment formulation may be
useful. In general, the selection of the pre-treatment
formulation to be used in this step often depends on
the nature of the contaminant. As an illustration, a
hydrogen fluoride or hydrogen fluoride mixture has been
found to facilitate the removal of polymeric material,
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such as poly(isobutylene) films. In addition,
pretreating or spotting agents are often added in many
applications, such as in garment care, to facilitate
removal of particularly difficult stains. Exemplary
solvents for use in pre-treatment formulations are
described in U.S. Patent No. 5,377,705 to Smith, Jr. et.
al., Other suitable additives, pre-treatments,
surface treatments, and chemical agents are known to
those skilled in the art, and may be employed alone or
in combination with other appropriate components for
use as a pre-treatment formulation in the process of
the invention.
The present ir~~ertior_ ? s explained in greater
detail herein in the following examples, which are
illustrative and are not to be taken as limiting of the
invention.
Example 1
Synthesis of polystyrene b-PFOA
A polystyrene-b-PFOMA block copolymer is
synthesized using the "iniferter" technique. The
polystyrene macroiniferter is synthesized first.
Into a 50-mL round bottom flask, equipped
with a stir bar is added 40 g de»hibited styrene
monomer and 2.9 g tetraethyltr.iu~am disulfide (Tiri . The
flask is sealed with a septum and purged with argon.
The flask is then heated for 11 hours at 65°C in a
constant temperature water bath. At the completion of
the reaction, the polymer solution is diluted with
tetrahydrofuran (THF) and precipitated into excess
methanol. The polymer is collected by suction
filtration and dried under vacuum. 13 g of polystyrene
is obtained. The resulting polystyrene is purified
twice by dissolving the polymer in THF and
precipitating the polymer into excess methanol. The
purified polymer has a molecular weight of 6.6 kg/mol
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and a molecular weight distribution (M",/M=,) of 1.8 by
GPC in THF.
. The block copolymer is synthesized by
charging 2.0 g of the above synthesized polystyrene
macroiniferter into a 50-mL quartz flask equipped with
a stir bar, along with 40 mL of a,a,a-trifluorotoluene
(TFT) and 20 g of deinhibited 1,1-dihydroperfluorooctyl
methacrylate (FOMA) monomer. The flask is sealed with a
septum and purged with argon. The flask is then
photolyzed for 30 hours at room temperature in a 16
bulb Rayonet equipped with 350 nm bulbs. At the end of
the reaction, the reaction mixture is precipitated into
cyclohexane, the polymer is collected and is dried
under vacuum. 10 g of polymer is obtained. The block
copolymer is purified by Soxhlet~extraction using
cyclohexane for two days. The block copolymer
composition is determined to be 41 mol % polystyrene
and 59 mol % PFOMA by 1H-NMR.
Example 2 .
Synthesis of PFOA-co-polystyrene
A statistical copolymer of
poly(1,1-dihydroperfluorooctyl acrylate) (PFOA) and
polystyrene is synthesized by charging 6..1 g
deinhibited FOA monomer, 1.4 g deinhibited styrene
monomer, and 0.10 g AIBN into a 25-mL high pressure
view cell equipped with a stir bar. The cell is then
closed and purged with argon. After purging, the cell
is heated to 60°C and pressurized with C02 to 4900 psa..
The reaction is run for 24 hours at which time the cell
contents are vented into methanol, with the polymer
being collected and dried under vacuum. 4.9 g of
polymer is obtained consisting of 54 mol % polystyrenes
'. and 46 mol % PFOA as determined by 1H-NMR.
Trader mark
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Example 3
Synthesis of PI~2A-b-PFOMA
A di-block copolymer of PMMA-b-PFOMA is
synthesized using the atom transfer radical
polymerization (ATRP) technique. The poly(methyl
methacrylate) (PMMA) macroinitiator block is
synthesized first.
Into a 50-mL round bottom flask equipped with
a stir bar is added 20 g deinhibited MMA, 0.6 mL (4x10-3
mol) ethyl-2-bromoisobutyrate, 0.6 g (4x10-3 mol)
copper(I) bromide, 1.9 g (1.2x10-' mol) 2,2'-dipyridyl
and 20 mL ethyl acetate. The flask is then capped with
a septum and purged with argon. After purging, the
flask is placed in a 100 °C oil bath for 5.5 hours. At
the end of the reaction, the reaction mixture is
diluted with ethyl acetate, passed through a short
column of alumina, and precipitated into methanol. The
polymer is then collected and dried under vacuum giving
15 g of polymer. The PMMA has a molecular weight of
8.1 kg/mol and a molecular weight distribution (MW/M")
of 1.3.
The block copolymer is subsequently prepared
from the above synthesized PMMA macroinitiator. Into a
5-mL round bottom flask equipped with a stir bar is
added 3.0 g (3.8 X 10-4 mol) of the above synthesized
PMMA macroinitiator, 30 g deinhibited FOMA, 0.054 g
( 3 . 8 x 10-4 mol ) copper ( I ) bromide , 0 . 18 g ( 1 . 1 x 10'3
mol) 2,2'-dipyridyl and 40 mL TFT. The flask is then
sealed with a septum and purged with argon. After
purging, the flask is placed in a 115°C oil bath for
5.5 hours. At the end of the time, the reaction
solution is diluted with fluorocarbon solvent, passed
through a small column of_alumina and precipitated into
THF. The polymer is collected and dried under vacuum
giving 7.5 g of polymer. The block copolymer is
purified by Soxhlet extraction using THF for four days.
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1H-NMR analysis of the block copolymer reveals it to
consist of 40 mol % PMMA and 60 mol % PFOMA.
Example 4
Synthesis of PDMAEMA-b-PFOMA
. 5 The poly(2-(dimethylamino)ethyl methacryla~te)
(PDMAEMA)-b-PFOMA diblock copolymer is synthesized
using the iniferter technique. The PDMAEMA block is
synthesized first and used as the macroiniferter for
the second block.
Into a 50-mL quartz flask equipped with a
stir bar is added 23.25 g deinhibited DMAEMA, 0.60 g
N,N-benzyl dithiocarbamate, and 2.2 mg tetraethyl-
thiuram disulfide. The flask is then sealed with a
septum and purged with argon. After purging,-the flask
is photolyzed for 30 hours at room temperature in a 7_6
bulb Rayonet~equipped with 350 nm bulbs. At the end of
the reaction, the reaction mixture is diluted with THF
and precipitated into hexanes. The polymer is collected
and dried under vacuum giving a yield of 22 g.
The diblock copolymer is synthesized from the
above synthesized PDMAEMA macroiniferter. Into a 50-mL
quartz flask equipped with a stir bar is added 1.0 g of
the above synthesized PDMAEMA macroiniferter, 25 mL of
TFT, and 20 g deinhibited FOMA monomer. The flask is
then sealed with a septum and purged with argon. Aft,.r
purging, the flask is photolyzed for 30 hours at room
temperature in a 16 bulb Rayonet equipped with 350 nm
bulbs. At the end of the reaction, the flask contents
are diluted with TFT and precipitated into hexanes. The
polymer is collected and dried under vacuum giving a
- yield of 7 g. The block copolymer is purified by
Soxhlet extraction using methanol for three days. 1H-NMR
reveals the block copolymer to consist of 17 mol
PDMAEMA and 83 mol % PFOMA. Thermal analysis gives two
glass transitions for the block copolymer; one at about
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25 °C and the other at about 51 °C corresponding to the
PDMAEMA and PFOMA blocks respectively.
Example 5
Syr~.thesa.s of PFOMA-co-PHEMA
A statistical copolymer of PPOMA and
poly(2-hydroxyethyl methacrylate) (PHEMA) is
synthesized in carbon dioxide.
The copolymer of PFOMA and PHEMA is
synthesized by charging 10.0 g deinhibited FOMA
monomer, 1.0 g deinhibited HEMA monomer, and 0.01 g
A1BN into a 25-mL high pressure view cell equipped with
a stir bar. The cell is then closed and purged with
argon. After purging, the cell is heated to 65°C and
pressurized with COa to 5000 psig. The reaction is run
for 51 hours after which the cell contents are vented
into methanol, with the polymer being collected and
dried under vacuum. 9.2 g of polymer is obtained
consisting of 19 mol o PHEMA and 81 mol o PFOMA as
determined by 1H-NMR. Thermal analysis reveals the
polymer to have a single glass transition at about
37°C.
Example 6
Synthesis of PHEMA-b-PFOMA
A di-block copolymer of PHEMA and PFOMA is
synthesized using ATRP. The PHEMA block would be
synthesized first using 2-(trimethylsilyloxy)ethyl
methacrylate (HEMA-TMS).
Into a 25-mL round bottom flask equipped with
'a stir bar is added 10 g deinhibited HEMA-TMS, 0.29 g
(2 x 10-3 mol) copper (I) bromide, 0.94 g (6 x IO-3 mol)
2, 2' -dipyidyl, and 0 .29 mL (2 x 10-3 mol) ethyl-2-
bromoisobutyrate. The flask is then sealed with a ,
septum and purged with argon. After purging, the flask
is placed in a 120°C oil bath for 5.5 hours after which
time it is diluted with THF, passed through a short
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column of alumina, and precipitated into water. The
polymer is collected and dried under vacuum to give a
yield of 3.7 g. The polymer has a molecular weight of
7.2 kg/mol and a molecular weight distribution (MW/Mn)
of 1.8.
The second block of the copolymer is
synthesized by dissolving a predetermined amount of the
above synthesized PHEMA-TMS macroinitiator in TFT,
adding an equal molar amount of copper(I) bromide,
adding three times the molar amount of 2,2'-dipyridyl
and adding a predetermined amount of FOMA monomer. The
reaction flask is then sealed with a septum and purged
with argon. After purging, the reaction flask is
placed into an oil bath at 115 °C for several hours.
The polymer is simultaneously isolated and deprotected
by precipitation into acidic methanol. The polymer is
collected and dried under vacuum. The resulting block
copolymer is purified by Soxhlet extraction for several
days.
Example 7
Solubility of poly(DMAEMA-co-FOMA)
in Supercritical Carbon Dioxide
The solubility of a statistical copolymer of
2-(dimethylamino)ethyl methacrylate (DMAEMA) and 1,1'
-dihydroperfluorooctyl methacrylate (FOMA) containing
23 mol % DMAEMA in C02 is determined by adding 4 wt/vol
of the copolymer to a high pressure view cell. The
cell is then heated and C02 is added to the desired
pressure. The copolymer is found to be completely
soluble, forming a clear, colorless homogeneous
solution at 65°C, 5000 psig; 40°C, 3600 psig; and also
at 40°C, 5000 psig.
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Examt~le 8
Solubility of poly(HEMA-co-FOMA)
in Supercritical Carbon Dioxide
The solubility of a statistical copolymer of
2-(hydroxy)ethyl methacrylate (HEMA) and
FOMA containing 19 mol o EMA is determined as in '
Example 1. At 4 wt/vol o, the copolymer forms a clear,
colorless solution in COa at 65°C, 5000 psig; 40°C, 3500
psig; and 40°C, 5000 psig.
Example 9
Solubility of poly(VAc-co-FOA)
in Supercritical Carbon Dioxide
The solubility of a block copolymer of vinyl
acetate (VAc), and 1,1'-dihydroperfluorooctyl acrylate
(FOA) is determined as in Example 1. The vinyl acetate
block of the copolymer has a molecular weight (Mn) of
4.4 kg/mol, and the FOA block has a molecular weight of
43.1 kg/mol. The copolymer forms a clear, colorless
solution at 52 °C, 3450 psig and 40°C, 5000 psig, and a
cloudy solution at 65°C, 5000 psig, and at 40°C, 3000
psig.
Example l0
Solubility of poly(FOA-VAc-b-FOA)
is Supercritical Carbon Dioxide
The solubility of an AHA triblock block
copolymer of vinyl acetate (VAc), and 1,1'-dihydro
perfluorooctyl acrylate (FOA) is determined as in
Example 1. The vinyl acetate block of the copolymer
has a molecular weight (Mn) of 7.1 kg/mol, and the FOA
blocks have a total molecular weight of 108 kg/mol. The
copolymer forms a clear, colorless solution at 65°C,
4900 prig, and at 28°C, 2400 psig_
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Example 11
Solubility of poly(DMAEMA-b-FOMA)
in Supercritical Carbon Dioxide
The solubility of a block copolymer of DMAEMA
and FOMA is determined as in Example 1. The copolymer
contains 17 mol ~ DMAEMA. The copolymer forms a clear,
colorless solution in C02 at 40°C, 5000 psig, and a
slightly cloudy solution at 65°C, 5000 psig, and 40°C,
3600 psig.
Example 12
Solubility of poly(Sty-b-POA)
in Supercritical Carbon Dioxide
The solubility of a block copolymer of
styrene (Sty) and FOA is determined as in Example 1.
The molecular weight (Mn) of the styrene block is 3.7
kg/mol and the molecular weight of the FOA block is
27.5 kg/mol. The copolymer forms a slightly cloudy
solution in C02 at 65°C, 5000 psig, and at 40°C, 5000
psig.
Example 13
Solubility of poly(Sty-b-FOA)
in Supercritical Carbon dioxide
The solubility of a block copolymer of
styrene (Sty) and FOA is determined as inExample 1.
The molecular weight (Mn) of the styrene block is 3.7
kg/mol and the molecular weight of the FOA block is
39.8 kg/mol. The copolymer forms a clear, colorless
solution in C02 at 65°C, 5000 psig, and at 40°C, 5000
psig.
Example 14
Solubility of poly(Sty-b-FOA)
in Supercritical Carbon Dioxide
The solubility of a block copolymer of
styrene (Sty) and FOA is determined as in Example 1.
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The molecular weight (M") of the styrene block is 3.7
kg/mol and the molecular weight of the FOA block is
61.2 kg/mol. The copolymer forms a clear, colorless
solution in CO~ at ~0°C, 5000 psig and a slightly cloudy
solution at 60°C, 5000 psig.
Examt~ 1 a 15
Synthesis of poly(hexafluoropropylene oxide-b-propylene
oxide) Oligomeric Surfactant
Acid fluoride terminated poly(hexafluoro
propylene oxide) oligomer is reacted with amine (or
diamino) functional polypropylene oxide) oligomer to
form a low molecular weight block type surfactant for
use in C02 applications.
Example 16
Synthesis of Diethanolamide Functional
Perfluoropolyether
Acid fluoride terminated poly(hexafluoro-
propylene oxide) is treated with diethanol amine in the
presence of triethylamine to prepare diethanolamide
functional poly(hexafluoro- propylene oxide) for use in
C02 applications.
Example 17
Characterization of poly(FOA-g-ethylene oxide)
in Carbon Dioxide Using Scattering Techniques
The solution and aggregation phenomena of a
graft copolymer with a poly(FOA) backbone and
polyethylene oxide) (PEO) grafts were investigated in
supercritical C02 with and without water present. The
copolymer contained 17 wt ~ PEO, and was found to
aggregate strongly with and without water present, and
to carry a significant amount of water into C02 under
various conditions. These characteristics are
indicative of surface activity.
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Example 18
Solution Properties of poly(FOA) i.n COa
in the Presence of a Non-Solvent (for PFOA) Co-Solvent
An investigation of the solution properties
of poly(FOA) in COz as a function of the amount of co-
solvent added using small angle neutron scattering
techniques shows that small amounts of methyl
methacrylate added to the system as a co-solvent
improve the solubility of poly(FOA) in
CO2. The investigation also revealed that larger
amounts (greater than 10 °s) adversely effects the
solubility of poly(FOA) in C02. Experiments are carried
out at 65°C, 5000 psig, 0.8 to 10 wt/vol o poly(FOA)
and up to 20 °s methyl methacrylate added to the system.
This data shows that the addition of small amounts of
co-solvent relative to COZ - even one that is a
non-solvent for the targeted solute - can improve the
solubility of a solute in CO2.
Example 19
Solution and Aggregation Behavior of
poly(FOA-b-Sty) Copolymers in COZ as a
Function of Co-Solvent
An investigation of the behavior of three
poly(FOA-b-Sty) block copolymers in C02 using scattering
techniques shows that when sufficient styrene monomer
is added to the system as a co-solvent. The block
copolymers aggregate strongly (indicating surface
activity) without added styrene and form solutions of
unimers in the presence of enough styrene co-solvent.
Three copolymers with compositions of PFOA/Sty (kg/mol)
of 16.6/3.7, 24.5/4.5, and 35/6.6 are studied at
concentrations of 2 and 4 wt/vol~ copolymer with up to
20 wt/vol °s added styrene over a range of pressures and
temperatures.
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Example 20
Solution Behavior of poly(FOA-b-DMS) in COa
The solution behavior of a block copolymer
containing a 27 kg/mol block of PDMS and a 167 kg/mol
block of PFOA is shown to be well solvated and not to
form aggregates in C02 at 25°C, 2880 psig and at 40°C,
5000 psig using scattering techniques.
Examt~le 21
Aggregation of poly(FOMA-b-Sty) in COz
A block copolymer containing blocks of 42
kg/mol poly(FOMA) and 6.6 kg/mol polystyrene is shown
to form aggregates in COz, indicating surface activity
similar to that of poly(FOA-b-Sty) copolymers of
similar relative composition.
Examt~le 22
Solution and Aggregation Behavior of poly(DMS-b-Sty)
Copolymers in COa as a Function of Co-Solvent
The solution and aggregation behavior of a
block copolymer containing a block of 5 kg/mol
polystyrene and a block of 25 kg/mol of poly(dimethyl
siloxane) as a function of added co-solvent is studied
using scattering techniques. Either isopropanol or
styrene monomer are employed as co-solvent. With
little or no co-solvent, small angle neutron scattering
shows the formation of aggregates in the solution. As
more co-solvent is added, the aggregates break up
confirming that co-solvents and modifiers can indeed be
employed to tune the surface activity of surfactants in
COZ solutions.
Example 23
Entrainment of C02-Insoluble Polystyrene Homopolymer
into COZ Using poly(FOA-b-STY) Surfactant '
A COa-insoluble polystyrene sample is placed
in a high pressure view cell and treated with a
solution of poly(FOA-b-Sty) in supercritical CO2.
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Examination of the original treating surfactant
solution and the resulting dispersion of polystyrene in
COZ using small angle neutron scattering confirms that
the polystyrene is indeed entrained in the COZ by the
block copolymer surfactant. Visual inspection of the
316 stainless steel surface where the C02-insoluble
polystyrene was placed indicates that the surface has
been cleaned of polystyrene.
Example 24
Emulsification of Machine Cutting Fluid With
Low Solubility in C02 Using
Block Copolymers of poly(FOA) and polyvinyl acetate)
A machine cutting fluid which exhibits low
solubility in C02 is emulsified in COa using an ABA
block copolymer surfactant, poly(FOA-b-Vac-b-FOA) with
a 7.1 kg/mol vinyl acetate center block and 53 kg/mol
(each) end blocks. A solution of several percent of
the block copolymer surfactant and 20 wt/vol % of the
cutting oil forms a milky white emulsion with no
precipitated phase observed.
Example 25
Solution Behavior of Polydimethyl Siloxane Homopolymer
in COa as a Function of Added Co-Solvent
A small angle neutron scattering study of the
solution properties of polydimethyl siloxane dissolved
in COZ shows that in pure C02 at 65°C, and room temp
(ca. 20°C), 3500 psig shows that pure C02 is a
thermodynamically poor solvent for the 33 kg/mol sample
employed. Addition of isopropanol as a co-solvent
results in a thermodynamically good solvent for the
same sample under identical conditions. This result
shows that even minor amounts of a co-solvent or
modifier can alter the interactions of C02 with the
C02-philic portion of an amphiphile designed for CO2
applications.
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Examt~le 26
Cleaning of polystyrene) Oligomer from Aluminum
A 0.1271 g sample of COz insoluble 500 g/mol
solid polystyrene) is added to a clean, preweighed
aluminum boat which occupies the bottom one-third of a
25-mL high pressure cell. A 0_2485 charge of an
amphiphilic species, a 34.9 kg/mol poly(l,l'-
dihydroperfluorooctylacrylate) - b - 6.6 kg/mol
polystyrene) block copolymer is added to the cell
outside of the boat. The cell is equipped with a
magnetically coupled paddle stirrer which provides
stirring at a variable and controlled rate. C02 is
added to the cell to a pressure of 200 bar and the cell
is heated to 40°C. After stirring for 15 minutes, four
cell volumes, each containing 25 mL of C02 is flowed
through the cell under isothermal and isobaric
conditions at 10 mL/min. The cell is then vented to
the atmosphere until empty. Cleaning efficiency is
determined to be 36% by gravimetric analysis.
Example 27
Cleaning of High Temperature Cutting Oil from Glass
A 1.5539 g sample of high temperature cutting
oil was smeared on a clean, preweighed glass slide (1"
x 5/8" x 0.04") with a cotton swab. A 0.4671 g sample
of Dow Corning~ Q2-5211 surfactant and the contaminated
glass slide are added to a 25-mL high pressure cell
equipped with a magnetically coupled paddle stirrer.
The cell is then heated to 40°C and pressurized to 340
bar with CO2. After stirring for 15 minutes, four cell
volumes each containing 25 mL of C02 is flowed through
the cell under isothermal and isobaric conditions at 10
mL/min. The cell is then vented to the atmosphere.
Cleaning efficiency is determined to be 78% by .
gravimetric analysis.
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Example 28
Cleaning of polystyrene) Oligomer from Glass
A 0.0299 g sample of polystyrene oligomer (MI,
- 500 g/mol) was smeared on a clean, preweighed glass
slide (1" x 5/8 x 0.04") with a cotton swab. A 0.2485
g charge of an amphiphilic species, a 34.9 kg/mol
poly(1,1'-dihydroperfluorooctylacrylate) - b - 6.6
kg/mol polystyrene) block copolymer, and the
contaminated glass slide are added to a 25-mL high
pressure cell equipped with a magnetically coupled
paddle stirrer. The cell is then heated to 40°C and
pressurized to 340 bar with COz. After stirring for 15
minutes, four cell volumes, each containing 25 mL of
C02, is flowed through the cell under isothermal and
isobaric conditions at 10 mL/min. The cell is then
vented to the atmosphere. Cleaning efficiency is
determined to be 90o by gravimetric analysis.
Examples 29-30
Cleaning of poly(styrene)oligomer from Aluminum
Using Various Amphiphilic Species
Examples 29-30 illustrate the cleaning of
polystyrene) oligomer from aluminum by employing
different amphiphilic species.
Example 31
The substrate described in Example 26 is
cleaned utilizing perfluorooctanoic acid as the
amphiphilic species.
Example 32
The substrate described in Example 26 is
cleaned utilizing perfluoro(2-propoxy propanoic) acid
as the amphiphilic species.
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Examples 33-45
Cleaning of various substrates
Examples 33-45 illustrate the cleaning of a _
variety of substrates by employing different
amphiphilic species according to the system described
in Example 26. The contaminants removed from the
substrates include those specified and others which are
known.
Example 33
The system described in Example 26 is used to
clean a photoresist with poly(1,1'-dihydroperfluoro-
octyl acrylate-b-methyl methacrylate) block copolymer.
The photoresist is typically present in a circuit board
utilized in various microelectronic applications. The
cleaning of the photoresist may occur after
installation and doping of the same in the circuit
board.
Example 34
The system described in Example 26 is used to
clean the circuit board described in Example 6 with
poly(1,1'-dihydroperfluorooctyl acrylate-b-vinyl
acetate) block copolymer. Typically, the circuit board
is cleaned after being contaminated with solder flux
during attachment of various components to the board.
Example 35
The system described in Example 26 is used to
clean a precision part with poly(1,1'-dihydroperfluoro
octyl methacrylate-b-styrene) copolymer. The precision
part is typically one found in the machining of
industrial components. As an example, the precision
part may be a wheel bearing assembly or a metal part
which is to be electroplated. Contaminants removed
from the precision part include machining and
fingerprint oil.
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Examt~le 36
The system described in Example 26 is used to
clean metal chip waste formed in a machining process
with poly(1,1'-dihydroperfluorooctyl acrylate-co-
styrene) random copolymer. Metal chip waste of this
type is usually formed, for example, in the manufacture
of cutting tools and drill bits.
Example 37
The system described in Example 26 is used to
clean a machine tool with poly(1,1'-dihydroperfluoro
octyl acrylate-co-vinyl pyrrolidone) random copolymer.
A machine tool of this type is typically used in the
production of metal parts such as an end mill. A
contaminant removed from the machine tool is cutting
oil.
Example 38
The system described in Example 26 is used to
clean an optical lens with poly(1,1'-dihydroperfluoro
octyl acrylate-co-2-ethylhexyl acrylate) random
copolymer. An optical lenses especially suitable for
cleaning include those employed, for example, in
laboratory microscopes. Contaminants such as
fingerprint oil and dust and environmental contaminants
are removed from the optical lens.
Example 39
The system described in Example 26 is used to
clean a high vacuum component with poly(1,1'-
dihydroperfluorooctyl acrylate-co-2-hydroxyethyl
acrylate) random copolymer. High vacuum components of
this type are typically employed, for example, in
cryogenic night vision equipment.
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Example 40
The system described in Example 26 is used to
clean a gyroscope with poly(1,1'-dihydroperfluorooctyl
acrylate-co-dimethylaminoethyl acrylate) random
copolymer. Gyroscopes of this type may be employed,
for example, in military systems and in particular,
military guidance systems. Contaminant removed from
the gyroscope are various oils and particulate matter.
Examt~le 41
The system described in Example 26 is used to
clean a membrane with poly(1,1'-dihydroperfluoro-
octylacrylate-b-styrene) block copolymer. Membranes of
this type may be employed, for example, in separating
organic and aqueous phases. In particular, the
membranes in are especially suitable in petroleum
applications to separate hydrocarbons (e. g., oil) from
water.
Example 42
The system described in Example 26 is used to
clean a natural fiber with poly(1,1'-dihydroperfluoro-
octyl acrylate-b-methyl methacrylate) block copolymer.
An example of a natural fiber which is cleaned is wool
employed in various textile substrates (e. g., tufted
carpet) and fabrics. Contaminants such as dirt, dust,
grease, and sizing aids used in textile processing are
removed from the natural fiber.
Examt~le 43
The system described in Example 26 is used to
clean a synthetic fiber with poly(1,1'-dihydroper
fluorooctyl acrylate-b-styrene) block copolymer. An
example of a synthetic fiber which is cleaned is spun
nylon employed solely, or in combination with other
types of fibers in various nonwoven and woven fabrics.
Contaminants such as dirt, dust, grease, and sizing
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aids used in textile processing are removed from the
synthetic fiber.
Example 44
The system described in Example 26 is used to
clean a wiping rag used in an industrial application
with poly(1,1'-dihydroperfluorooctyl acrylate-co-
dimethylaminoethyl acrylate) random copolymer. Grease
and dirt are contaminants removed from the wiping rag.
Examt~le 45
The system described in Example 26 is used to
clean a silicon wafer with poly(1,1'-dihydroper
fluorooctyl acrylate-co-2-hydroxyethyl acrylate) random
copolymer. The silicon wafer may be employed, for
example, in transistors which are used in
microelectronic equipment. A contaminant which is
removed from the silicon wafer is dust.
Example 46
Utilization of Co-Solvent
The system described in Example 26 is cleaned
in which a methanol cosolvent is employed in the COz
phase.
Example 47
Utilization of Rheology Modifier
The system described in Example 26 is cleaned
in which a rheology modifier is employed in the COa
phase.
Example 48
Cleaning a Stainless Steel Sample
A coupon of 316 stainless steel is
contaminated with a machine cutting fluid that exhibits
very low solubility in carbon dioxide. The coupon is
then placed in a high pressure cleaning vessel and
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cleaned with a mixture of carbon dioxide and a
siloxane-based amphiphilic species. After the modified
C02 cleaning process, the coupon is visually cleaned of
cutting oil. A control experiment with pure COa does
not result in the cleaning of the cutting fluid from
the coupon.
Example 49
Cleaning a Textile Material With Water in COa
An International Fabricare Institute standard
sample of cotton cloth stained with purple food dye is
cleaned using a formulation of 2 wt/vol % of a
siloxane-based ethoxylated amphiphilic species in
liquid COZ at room temperature with 2 wt/vol % of water
added as a modifier. After cleaning, the purple
stained cotton cloth is visibly much cleaner and has
lost most of the purple color. Controls run using
amphiphilic species or water alone with C02 showed no
significant removal of the food dye stain from the
cloth.
Example 50
Cleaning a Textile Material With Water and
a Co-Solvent in Liquid COa
A purple food dye stained standard fabric is
cleaned using a procedure similar to Example 49 except
that the C02-based cleaning formulation employs 2 wt/vol
~ of the siloxane-based ethoxylate amphiphilic species,
2 wt/vol a water, and 10 wt/vol % isopropanol co-
solvent in liquid COa at room temperature. After
cleaning, no trace of the purple food dye was visible
on the cloth sample.
Example 51
Cleaning a Textile Material
A purple food dye stained standard fabric
sample is 'cleaned using a procedure similar to Example
49 except that the C02-based cleaning formulation
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employs ethanol ~s the co-solvent instead of
isopropanol. The purple food dye was substantially
removed by the C02-fluid cleaning process.
Example 52
Cleaning a Machine Part in a Multi-Component System
A machine part is placed in a high pressure
view cell and is treated with supercritical COZ fluid
containing an amphiphilic species, co-solvent, co-
surfactant, and corrosion inhibitor. The treated
machine part displays less contaminant than prior to
contact with the above fluid.
Example 53
Cleaning a Fabric a.n a Multi-Component System
A soiled fabric sample is placed in a high
pressure view cell and is treated with supercritical COZ
fluid containing an amphiphilic species, co-solvent,
co-surfactant, and bleaching agent. The treated fabric
sample is cleaner than prior to contact with the above
fluid.
The foregoing examples are illustrative of
the present invention, and are not to be construed as
limiting thereof. The invention is defined by the
following claims, with equivalents of the claims to be
included therein.
