Note: Descriptions are shown in the official language in which they were submitted.
7 8
~lO 94/l9384 PCT/US93/01382
TITLE
ALTERNATING (AB~)n POLYL~CTIDE BLOCK COPOLYMERS
BACKGROUND OF THE INVEI~TTION
1. Field of the Invention:
The present invention relates to biodegradable multiblock
copolymers. More specifically, the invention relates to multiblock
copolymers involving sequentially ordered blocks of polylactide and/or
polyglycolide produced by ring-opening polymerization of lactide and/or
0 glycolide onto either an oligomeric diol or diamine residue followed by chain
extension with a difunctional compound.
2. Description of the Related Art:
Ring opening polymeriation of lactones and their initiation by
active hydrogen compounds to generate difunctional polymers is reported by
K. J. Ivin, and T. Saegusa, Rin~ Opening Polymerization, Vol 1, Ch. 7 (1984),
pp 461-521.
Preparation of block copolymers in which at least one block is a
polylactone has been achieved either by simultaneous or sequential
polymerization. For example, D. W. Grijpma, G. J. Zondervan, and A. J.
Pennings, Polymer Bul., Vol 25 (1991), pp 327-333 prepared random block
copolymers of e-caprolactone and lactide by simultaneous polymerization.
The different reactivity ratio of the two monomers leads to a block copolymer
with random block distribution. A. Hamitou, R. Jerome, and P. Teyssie, J.
Polym. Sci.: Pol. Chem. Ed., Vol 15 (1977), pp 1035-1401 used bimetallic u-
oxoalkoxides to prepare AB copolymers of e-caprolactone and
-propiolactone by sequential monomer addition. X. D. Feng, C. X. Song,
and W. Y. Chen, J. Polvm. Sci.: Pol. Letters Ed., Vol 21 (1983), pp 593-600
reported the preparation of AB b}ock copolymers of e-caprolactone and
lactide using the same procedure.
Preparation of ABA copolymers through living polymerization
is more difficult and requires modification of the growing AB intermediate.
C. X. Song, and X. D. Feng, Macromolecules, Vol 17 (1984), pp 2764-2767
prepared ABA trtiblock copolymers of e-caprolactone-lactide~-caprolactone
by converting the PCL-PLA-OAl to PCL-PLA-(OCH2CH2)2 4-OAl species
3~ which can reinitiate caprolactone polymerization for the third block.
Australian Published Patent Application No. 50602/90
discloses poly(ester-silicone) block copolymers wherein a hydroxyl terminated
poly(organosiloxane) oligomer and a hydroxyl terminated polyester
comprised of lactide and glycolide units are randomly linked by a
WO 94/19384 21 ~ ~ ~ 7 ~ PCT/US93/01382 ~
-- 2
diisocyanate compound, resulting in a random sequence of polyester blocks
and poly(organosiloxane) blocks along the copolymer chain.
German Offenlegungsschrift DE391157 A1 discloses block
copolymers wherein one type block is formed from an aliphatic
5 polycarbonate, and the other type block is a polylactone, or a copolymer of a
lactone and a carbonate.
Japanese Application No. 59-27923 discloses poly(ether-ester)
block copolymers. These copolyrners are- pro~uced in a manner similar to the
Australian Published Patent application cited above by reacting hydroxy
0 terrninated polyethers and hydroxy terminated polyesters with a
bis-acyl-lactone linker, to produce a random block distribution.
Barbskaya et al. in '~ole of Hydroxyl-Cont~ining Compounds
in Processes of Cationic Polymerization of dl-Lactiden, translation from
Polymer Science U.S.S.R., Vol 25, No 1, pp. 1788-1793 (1983) describe the
5 effect of octyl alcohol, glycolic acid and water on cationic polymerization of dl-Lactide, in the melt using SnCl 2H2O catalyst.
In U. S. Patents 2,878,236 and 3,169,945, lactone polyesters are
described wherein the lactone starting material is identified as having at leastsix carbon atoms to avoid a tendency for the resulting polymer to revert to the
20 monomer.
SUIVII~ARY OF THE INVENTION
The present invention provides a process for the preparation of
perfectly altering block copolymers (ABA)n in which A block is a
25 biodegradable polylactide, polyglycolide or substituted polyglycolide. The
process comprises: polymerizing cyclic diesters from hydroxy or amino groups
of a preformed B block (see equation 1 below~, followed by reacting the
dihydoxy ABA blocks with a difunctional linker (diisocyanates,
diacyclchlorides, dichlorosilanes) to repeat the ABA structure along the
30 copolymer chain (see equation 2):
2~S~78
~O 94/19384 3 _ , PCT/US93/01382
XO-B--OX ~ 2~ R2R~Ç~Q ~ ~ H~O--C ~ B--Ot~-C~
o~cR1R2 C;s~a~sl R~ R~
H3-ABA~
S
~-AB~OH ~ tLto--C-Cto--B--OtC-C~ 2)
0 The role of the difunctional linker Y-L-Y is simply to provide an increase in
copolymer molecular weight. The physical, mechanical and thermal behavior
of the perfectly alterinating copolymers will be controlled by: (a) nature of B
block, (b) copolymer chemical composition, and (c) crystallinity of A and B
blocks. When the starting cyclic diester is a chiral material, the
semicrystalline.A blocks can provide the same function (physical crosslinking)
as urethane hard segments in polyurethane segmented copolymers.
Thus the present invention further provides block copolymers
of the formula R(A-B-A-L)XA-B-A-R where -B- is an oligomeric diol residue
or an oligomeric diamine residue having a number average molecular weight
~o of 500 to 20,000, -A- is a polylhydroxy acid block comprising either a
polylactide, polyglycolide, or copolymer thereof having a number average
molecular weight 500 to 40,000, x is 1 to 100, and -L- is the chain extender
residue derived from an diacyl halide, diisocyanate, or the like containing 8 to20 carbon atoms, and -R is hydrogen, chain extender residue or an end-
2~ capping group, wherein the resulting block copolvmer has a number average
molecular w eight of greater than 10,000.
DESCRIPTION OF THE PREFERRED EMBODIMEI~S
The present invention provides a method for the preparation of
3~ R(A-B-A)XA-B-A-R polymers in u hich x is 1 to 100, and the -A-s are
biodegradable polyhydroxyacid blocks. The type -B- block can be widely
varied and virtually any difunctional oligomer having two hydroxyl or primary
amino end groups can be used. The invention contemplates forming
multiblock copolymers with uniformly alternating triblocks of different
3~ chemical compositions ~ hich can cover the whole range of properties from
hard (_lassy) plastics, to soft (toughened) plastics to elastomers for a wide
range of applications.
The -B- block can be widely varied. Generally the -B- blocks
have a number average molecular weight of from 500 to 20,000 wilh ~,000 to
wo 94/lg384 21~ 5 6 7 8 4 _ PCT/US93/01382~
8,000 being the preferred range. The starting material, from which the -B-
block is derived, is characterized by the formula H-B-H where each -H is part
of a terminal -NH2 or -OH group. Thus the -B- can be a derived from a
dihydroxyterrninated polyether (i.e., a telechelic polyether) ~vith repeating
5 units of the structure~Rl-O~ where -Rl- is~CH2~z where z is 2 to 6 or
mixtures thereof. The -B- can also be derived from a dihydroxyterminated
polyester (i.e., a telechelic polyester) having repeating units of the structure:
1t
~CH23--mO-C-R2-C~
10 where m is 2 to 6 and -R2- is a divalent aliphatic, cycloaliphatic or aromatic
group having 2 to 20 carbon atoms. The -B- can be formed from dihydroxy
terminated (telechelic) polyesters having repeating units of the structure
o
tC-R3-o~
where -R3- is a divalent aliphatic, cycloaliphatic or aromatic group having 6
to 20 carbon atoms. The -B- can also have the structure:
R5 R5 R5
-R4-Si-otSi-o3~ Si- R4-
R5 R5 R5
where the -R4s are alkylene groups containing 3 to 10 carbon atoms, with a
terminal amino or hydroxy function, the -R5s are independently selected from
the group consisting of hydrogen, saturated or unsaturated aliphatic radicals
containing 1 to 20 carbon atoms (preferably 1 to 6 carbon atoms), aromatic
radicals containing 6 to 20 carbon atoms, and perfluoroalkyl radicals
containing 1 to 20 carbon atoms (preferably 1 to 6 carbon atoms) and n is 15
to 150. Most preferably, the -R5s are C1 to C6 alkyl, phenyl, vinyl, or 3,3,3-
trifluoropropyl radicals.
The -A- blocks are formed by ring opening polymerization of
simple lactones with the general formula:
0
C
(R5R6C) O
where R5 and R6 are the same or different and are hydrogens, aliphatic
groups of 1 to 10 carbon atoms or aromatic groups of 6 to 12 carbon atoms,
andmis2to 10.
2~55~78
~0 94/19384 PCT/US93/01382
Diester lactones useful in the present invention have the
general formula:
R7 ~
R8- ~ / \O
R9
O C _ R10
~C / ''`
where -R7, -R8, -R9, and -R10 are the same or different and are hydrogen, an
aliphatic group of 1 to 10 carbon atoms or an aromatic group of 6 to 12
carbon atoms.
In a preferred aspect of the invention, the -A- blocks are
polylactide wherein 98 to 100~c of the lactide used to form the polylactide is
one of either D-lactide or L-lactide, to provide a significant degree of
crystallinity within the -A- block. The individual -A- blocks generally have a
number average molecular weight of 500 to 40,000 with 2,000 to 20,000 being
the preferred range. Thus, generally from 99 to 5 wt.~o of the polymer
(ignoring the chain extension and end-capping contributions) will be -A-
blocks and 1 to 9S wt.~c -B- blocks with from 99 to 50 wt.~o -A- blocks and 1
to 50 wt.~o -B- blocks being the preferred range. The polymer is prepared by
polymerizing the L-lactide or D-lactide onto a preformed -B- block to form
what is in principle the intermediate H-A-B-A-H copolymer block. It should
be appreciated that this intermediate corresponds literally to the '~IO-ABA-
OH" reactant of equation (2) above in that -A- polyhydroxy acid bloc~;
involves the acly group of lactide being bonded to the gro~ving polymer thus
leaving a terminal oxygen available for further chain growth, chain extension
and/or chain terrnination. The -A- blocks are formed by ROP (ring opening
polymerization) of lactone using ionic or nonionic catalysts as described in
'~ing Opening Polymerizationn, Vol.1, page 461-521, K. J. Ivin and T.
Saeg~sa (1984). The catalysts include coordination catalysts such as stannous
2-ethylhexanoate (tin octanoate), or a yttrium or lanthanide series rare earth
metal based catalyst (coordination catalyst) such as described in U.S. Patent
No. 5,028,667. The polymerization is generally done at -100 to 200C vith
10 to 180C being the preferred range. The polymerization may be done in
solution or in the melt without a solvent. The final chain extended polymers
of the present invention generally melt in the range of 80 to 170C.
WO 94/19384 ~ ~ ~ 5 6 7 8 -- 6 -- PCT/US93/01382
The H-A-B-A-H triblocks (the HO-ABA-OH of equation 2)
are reacted with a chain extender to form a polymer of the formula
R~-B-A-L~XA-B-A-R where -L- is the residue of the chain extending agent
and the terminal -Rs are hydrogen radicals, (forming terminal -OH groups),
the residue of the chain extending agent or optionally an end-capping group
such as an acyl radical, -C(O)R' where R' is an alkyl group containing 1 to 10
carbon atoms or an aryl group cont~ining 6 to 12 carbon atoms (forming
terminal ester groups) or equivalent end-capping group as genera~ly known in
the art. Suitable chain extending agents are diisocyanates and diacyl
0 chlorides cont~ining 8 to 20 carbon atoms. The molar ratio of H-A-B-A-H
(i.e., HO-ABA-OH~, to chain extender should be about 1:1. The chain
extending reaction can be done in bulk or in solution. Suitable temperatures
for the chain extending reaction are 2S to 180C with from 100 to 150C
being the preferred range. Suitable solvents for the lactide polymerization
and chain extending reactions should be non-reactive organic liquids capable
of dissolving at least 1 Wt.~G and preferably over 10 wt.% of chain extended
polymers at 25C. The product polymers generally have number average
molecular weights of greater than 10,000 with 30,000 to 250,000 being the
preferred range.
The polymers of the present invention are biodegradable and
the toughened plastics find use as general purpose molding resins. The
elastomeric products are useful in typical elastomeric applications such as
rubber bands, seals, etc.
EX~IPLE 1
Synthesis of 90/10 Wt.~G Polylactide/
Polv(Butylene-Ethylene Adipate)
In a dry box, 22.5 g (156.2 mmoles) klactide and 2.5 g (0.735
mmoles) hydroxyl terminated poly(butylene-ethylene adipate), PBEA, with
Mn of 3,400 g/mole were weighed into an oven dried 100 ml. round bottom
flask equipped with overhead stirrer, addition funnel and nitrogen inlet. The
reaction flask was then transferred into the hood, placed under a dry nitrogen
atmosphere, and heated in an oil bath to 120C. The homogeneous melt was
reacted for one hour at 120C, in the absence of catalyst, to allow initiation of
polymerization at the hydroxyl endgroups of the PBEA oligomer. After one
hour, 0.8 ml stannous 2-ethylhexanoate, SnOct, solution (0.lM in toluene)
was added (Monomer/Catalyst = 2000/1 molar ratio), and the reaction was
allowed to proceed for 2 more hours at 120C. The reaction viscosity
21~5~78
~o 94/19384 PCTIUS93/01382
-- 7
increased considerably after catalyst addition and 5-10 ml freshly distilled
toluene were added (via syringe) to facilitate ease of stirring. A clear, viscous
solution of A-B-A copolymer was formed at the end of the two hours. 5
Ml toluene and 0.11 ml (0.772 mmoles, 5% excess) toluene diisocyanate, TDI,
s were syringed into the addition funnel and the TDI solution was added to the
reaction mixture drop-wise, over 30 minutes. During TDI addition, the
reaction viscosity increased considerably and more toluene had to be added
to m~int~in a homogeneous reaction mixture The final reaction
concentration was about 60Yo solids. At the end of TDI addition, the reaction
10 mLl~ture was cooled to room temperature, the polymer dissolved in 200 ml
CH2Cl2, precipitated from hexane, and dried in a vacuum oven at room
temperature for at least 24 hours.
Polymer properties:
Weight average molecular weight (Mw)= 98,200 as determined
15 using gel permeation chromatography using a polystyrene standard (GPC, PS
STD); melting temperature (Tm) = 166C as determined using differential
sc~nnin~ calorimetry (DSC); glass transition temperature (Tg) = 43C by
calorimetry (DSC); Tensile Strength (TS) = 8,100 psi; Initial Modulus (of
elasticity in flex) = 188,000 psi; Elongation at break = 6%.
EXAMPLE 2
Svnthesis of 75/25 wt.~G Polylactide/
Poly(Butylene-Ethylene Adipate)
In a dry box, 18.0g (125 mmoles) L-Lactide and 6.0g (1.76
2s mmoles) hydroxyl terminated PBEA with Mn of 3,400g/mole were weighed
into an oven dried 100 ml. round bottom flask equipped with overhead
stirrer, addition funnel and nitrogen inlet. The reaction flask was then
transferred into the hood, placed under a dry nitrogen atmosphere, and
heated in an oil bath to 120C. The homogeneous melt was reacted for one
30 hour at 120C, in the absence of catalyst, to allow initiation of polyrnerization
at the hydroxyl endgroups of the PBEA oligomer. After one hour, 0.65 ml
SnOct solution (0.lM in toluene) were added (M/Cat = 2000/1 molar ratio),
and the reaction was allowed to proceed for 2 more hours at 120C. The
reaction viscosity increased considerably after catalyst addition and 5 - 10 ml
3s freshly distilled toluene were added (via syringe) to m~int~in the ease of
stirring. A clear, viscous solution of A-B-A copolymer was formed at the end
of the two hours. 5 Ml toluene and 0.26 ml (1.848 mmoles, 5% excess) TDI
were syringed into the addition funnel and the TDI solution was added to the
WO 94/19384 , - 8 - PCT/US93/01382
reaction mixture drop-wise, over 30 minutes. During TDI addition, the
reaction viscosity increased considerably and more toluene had to be added
to m~int~in a homogeneous reaction mixture. The final reaction
concentration was about 60% solids. At the end of TDI addition, the reaction
mixture was cooled to room temperature, the polymer dissolved in 200 ml
CH2Cl2, precipitated from hexane, and dried in a vacuum oven at room
temperature for at least 24 hours.
Poly~ner properties:
Mw = 161,000 (GPC, PS STD); Tm = 151C (DSC); Tg = 25C (DSC); TS =
0 8,300 psi; Initial Modulus = 34,000 psi; Elongation at break = 630~o.
EX~MPLE 3
Synthesis of 50/50 Wt.YG Polvlactide/
Poly(Butylene-Ethylene Adipate)
In a dry box, 12.0 g (83.3 mmoles) L-Lactide and 12.0 g (3.53
mmoles) hydroxyl terminated PBEA ~;vith Mn of 3,400 g/mole were weighed
into an oven dried 100 ml. round bottom flask equipped with overhead
stirrer, addition funnel and nitrogen inlet. The reaction flask was then
transferred into the hood, placed under a dry nitrogen atmosphere, and
heated in an oil bath to 120C. The homogeneous melt was reacted for one
hour at 120C, in the absence of catalyst, to allow initiation of polymerizationat the hydroxyl endgroups of PBEA oligomer. After one hour, the reaction
temperature was increased to 150C, 0.4 ml SnOct solution (0.1 M in toluene)
were added (M/Cat = 2000/1 molar ratio), and the reaction was allowed to
proceed for 2 more hours at 150C. A viscous homogeneous melt was formed
shortly after catalyst addition, and the viscosity increased with reaction time.S Ml toluene and 0.53 ml (3.706 mmoles, 5~o excess) TDI were syringed into
the addition funnel and the TDI solution was added to the reaction mixture
drop-wise, over 30 minutes. During TDI addition, the reaction viscosity
increased considerably but the reaction mixture stayed clear all the way
through addition. At the end of TDI addition, the reaction mixture was
cooled to room temperature, and dissolved in 200 ml CH2C12. The polymer
was isolated by precipitation from hexane and dried in a vacuum oven at
room temperature for at least 24 hours.
Polymer properties:
Mw = 146,000 (GPC, PS STD); Tm = 98C (DSC); T~1
(PBEA) = 30C (DSC); Tg2 (PLA) = 52C (DSC); TS = 7,400 psi; Initlal
Modulus = 4,400 psi; Elongation at break = 1,100C~c.
21~5~78
~o 94/19384 ~ PCT/US93/0L~82
_ g
EX~MPLE 4
Synthesis of 80/20 wt.~c Polylactide/
Polytetramethvlene Oxide
In a dry box 20.0g (138.9 mmoles) L-Lactide and 5.0 g (1.724
5 mmoles) hydroxyl terminated polytetramethylene oxide (PTMO) with Mn f
2,900 g/mole were weighed into an oven dried 100 ml. round bottom flask
equipped with overhead stirrer, addition funnel and nitrogen inlet. The
reac~ion flask was then transferred in the hood, placed under a dry nitrogen
atmosphere, and heated in an oil bath to 120C, using a progr~mm~ble hot
0 plate. The homogeneous melt was reacted for one hour at 120C, in the
absence of catalyst, to allow initiation of polymerization at the hydroxyl
endgroups of PTMO oligomer. After one hour, the reaction temperature was
increased to 150C, 0.7 ml SnOct solution (0.lM in toluene) were added
(M/Cat = 2000/1 molar ratio), and the reaction was allowed to proceed for 2
more hours at 150C. A viscous homogeneous melt was formed shortly after
catalyst addition, and the viscosity increased with reaction time. S Ml toluene
and 0.26 ml (1.810 mmoles, 5~c excess) TDI were syringed into the addition
funnel, and the TDI solution was added dropwise into the reaction mixture,
over 30 minutes. During TDI addition, the reaction viscosity increased
20 considerably and a small amount of freshly distilled toluene was added to
keep the reaction stirring. At the end of TDI addition, the reaction mixture
was cooled to room temperature and dissolved in 200 ml CH2Cl2. The
polymer was isolated by precipitation from hexane, and dried in a vacuum
oven at room temper~ture for at least 24 hours.
25 Polymer properties:
Mw = 85,000 (GPC, PS STD); Tm = 152C(DSC); Tg = 40C
(DSC); TS = 7,000 psi; Initial Modulus = 115,000 psi; Elongation at break =
710%.
EXAMPLE 5
Svnthesis of 60/40 wt.~o Polvlactide/
Polytetramethylene Oxide
In a dry box, 15.0 g (104.2 mmoles) L-Lactide and 10.0 g (3.448
mmoles) hydroxyl terminated PTMO with Mn of 2,900 g/mole were weighed
3~ into an oven dried 100 ml round bottom flask equipped with overhead stirrer,addition funnel and nitrogen inlet. The reaction flask was then transferred in
the hood, placed under a dry nitrogen atmosphere, and heated in an oil bath
tO 120C. The homogeneous melt was reacted for one hour at 120C, in the
WO 94/19384 2 1 5 ~ 6 7 ~ - 1 o - PCT/US93/01382 ~
absence of catalyst, to allow initiation of polymerization at the hydroxyl
endgroups of PrMO oligomer. After one hour, the reaction temperature was
increased to 150C, 0.5 ml SnOct solution (0.lM in toluene) were added
(M/Cat = 2000/1 molar ratio), and the reaction was allowed to proceed for 2
more hours at 150C. A viscous homogeneous melt was formed shortly after
catalyst addition, and the viscosity increased with reaction time. 5 Ml toluene
and 0.51 ml (3.621 mmoles, 5~o excess) TDI were syringed into the addition
filnnel, and~the 'IDI solution was added dropwise into the reaction mixture,
over 30 mintltes During TDI addition, the reaction viscosity increased
0 considerably but stayed clear all the way through addition. At the end of TDIaddition, the reaction rnixture was cooled to room temperature and dissolved
in 200 ml CH2Cl2. The polymer was isolated by precipitation from hexane
and dried in a vacuum oven at room temperature for at least 24 hours.
Polymer properties:
Mw = 111,000 (GPC, PS, STD); Tm = 118C (DSC); Tg1 (PTMO) = -21C
(DSC); Tg2 (PLA) = 45C(DSC); TS = 7,400 psi; Initial Modulus = 4,700
psi; Elongation at break = 870~c.
EX~IPLE 6
2~ Svnthesis of 50/50 Wt.~G Polylactide/
Polyethvlene Oxide
In a dry box, 10.0 g (69.44 mmoles) L-Lactide and 10.0g (1.25
rnmoles) hydroxyl terminated polyethylene oxide (PEO) with Mn of 8,000
g/mole were weighed into an oven dried 100 ml round bottom flask equipped
25 with overhead stirrer, addition funnel and nitrogen inlet. The reaction flaskwas then transferred in the hood, placed under a dry nitrogen atmosphere,
and heated in an oil bath to 120C, using a programmable hot plate. The
homogeneous melt was reacted for one hour at 120C, in the absence of
catalyst, to allow initiation of polymerization at the hydroxyl endgroups of
30 PEO oligomer. After one hour, the reaction temperature was increased to
150C, 0.35 ml SnOct solution (0.lM in toluene) were added (M/Cat =
2000/1 molar ratio), and the reaction was allowed to proceed for 2 more
hours at 150C. A viscous homogeneous melt was formed shortly after
catalyst addition, and the viscosity increased with reaction time. 5 Ml toluene
35 and 0.19 ml (1.312 mmoles, 5~6 excess) TDI were syringed into the addition
funnel, and the TDI solution was added dropwise into the reaction mixture,
over 30 minutes. During TDI addition, the reaction viscosity increased
considerably but stayed clear all the way through addition. At the end of TDI
2 ~ 8
~0 94/19384 PCT/US93/01382
addition, the reaction mixture was cooled to room temperature and dissolved
in 200 ml CH2Cl2. The polymer was isolated by precipitation from hexane,
and dried in a vacuum oven at room temperature for at least 24 hours.
Polymer properties:
Mw = 111,000 (GPC, PS STD); Multiple Tms in DSC; Tgl
(PTMO) = -57C (DSC); Tg2 (PLA) = 37C (DSC); TS = 1,100 psi; Initlal
Modulus = 14,4000 psi; Elongation at break = 611~o.
EXAIVIPLE 7
0 Synthesis of 75t25 wt.~o Polylactide/
Polvethylene Oxide
A 100 ml flask is charged with 5.0g (1.47 mmole) polyethylene
oxide having a number average molecular weight of 3,400, 15.0g (104.16
mmoles) L-lactide and 0.26 ml of a 0.1 M solution of tin 2-ethylhexanoate in
5 toluene (monomer/catalyst 2000/1). The flask is heated to and maintained
at 150C. After 2 hours at 150C, 0.27g (1.544 mole) of toluene diisocyanate
in 5 ml toluene is added dropwise to the flask. After 30 minutes the
temperature of the flask is dropped to 25C and the product polymer is
dissolved in 200 ml CH2C12 and recovered by precipitation from hexane.
20 The product polymer is a toughened plastic having a weight average
molecular weight of 98,000, a wt~ ratio of A/B of 75/25, a glass transition
temperature of 20C, a melting point of 148C, an initial modulus of elasticity
of 38,000 psi, a tensile strength at maximum of 2,500 psi, and an elongation at
break of 470~o.
EXAMPLE 8
Synthesis of 75/25 wt.~o Polylactide/
Polycaprolactone Copolymer
A 100 ml glass flask is charged with 5.0 g (2.5 mmole)
polycaprolactone having a number average molecular weight of 2,000, 15.0 g
(104.26 mmoles) L-lactide, and 0.26 ml of a 0.1M solution of tin
2-ethylhexanoate in toluene (monomer/catalyst 2000/1). The flask is heated
to and m~int~ined at 150C. After 2 hours at 150C 0.46 g toluene
diisocyanate is added to the flask. After 30 minutes the flask is cooled to
3s 25C and the product polymer dissolved in 200 ml CH2CCI2 and recovered
by precipitation from hexane. The product polymer is a toughenea plastic
having a number average molecular weight of 98,000, a wt.~ ratio of A/B of
75/25, a glass transition temperature of 30C, a melting point of 140C, an
WO 94/19384 215 5 6 7 ~ - 12 - PCT/US93/01382~
initial modulus of elasticity of 40,000 psi, a tensile strength at m~ximllm of
5,540, and elongation at break of 6855~c.
EXAMPLE 9
Synthesis of 50/50 wt.~c Polylactide/Polycaprolactone
A 100 ml glass flask is charged with 10.0 g (5.0 mmole) of
polycaprolactone having a number average molecular weight of 2,000, 10.0 g
~69.44 mmole) of L-lactide, and 0.35 rnl of a 0.1M solution of tin
2-ethythexanoate in toluene (monomer/catalyst = 2000/1). The flask is
0 heated to and m~int~ined at 150C. After 2 hours at 150C, 0.91 g (5.25
mmole) of toluene diisocyanate is added to the flask. After 30 minlltes the
flask is cooled to 25C, and the product polymer dissolved in 200 ml CH2C12,
and recovered by precipitation from hexane. The product polymer is a
thermoplastic elastomer having a number average molecular weight of
72,500, a wt.% ratio of A/B of 50/50, a glass transition temperature of -14C,
a melting point of 56C/90C an initial modulus of elasticity of 2,000 psi, a
tensile strength at m~ximl~m of 440 psi, and an elongation at break of 990~c.
EXAMPLE 10
Synthesis of 50/50 wt.~c Polylactide/Polyethylene
Oxide Copolymer
A 100 ml glass flask is charged with 10.0 g (2.94 mmole) of
polyethylene oxide having a number average molecular weight of 3,400, 10.0 g
(69.44 mmole) of L-lactide, and 0.35 ml of a 0.1M solution of tin
2s 2-ethylhexanoate in toluene (monomer/catalyst = 2000/1). The flask is
heated to and maintained at 150C. After 2 hours at 150C, 0.54 g (3.1
mmole) toluene diisocyanate is added to the flask. After 30 minutes the flask
is cooled to 25C, and the product polymer dissolved in 200 ml CH2C12 and
recovered by precipitation from hexane. The product polymer is a
thermoplastic elastomer having an average molecular weight of , a wt.~
ratio of A/B of 50/50, two glass transition temperatures of -36C and 43C, a
melting point of 82C, an initial modulus of elasticity of 480 psi, and an
elongation at break of 410%.
Having thus described and ~xemplified the invention with a
3s certain degree of particularity, it should be appreciated that the following
claims are not to be so limited but are to be afforded a scope commensurate
with the wording of each element of the claim and equivalents thereof.
