Biodegradable graft copolymers
First Claim
1. Method for converting a polysaccharide to a biodegradable thermoplastic graft copolymer capable of forming homogeneous blends with synthetic thermoplastic polymers, said method comprising the steps ofchemically treating said polysaccharide to form on said polysaccharide nucleophilically displaceable groups at a substitution level of about 0.1 to about 0.75 nucleophilic displaceable groups per anhydroglucose unit of said polysaccharide;
- forming an anionic polymer of the formula ##STR4## wherein R1 is C1 -C6 alkyl or a group of the formula ##STR5## by (1) anionic polymerization of a compound of the formula R--CR═
CH2 and (2) treatment with a compound of the formula X═
C═
Z, wherein in the above formulas R and R'"'"' are independently hydrogen, C1 -C6 alkyl, phenyl, substituted phenyl or methoxycarbonyl;
X and Z are each independently O or S;
M+ is an alkali metal cation; and
n is an integer such that the group ##STR6## has a molecular weight between about 3000 and about 25,000;
reacting said anionic thermoplastic polymer with said polysaccharide-bearing nucleophilically displaceable groups under conditions conducive to nucleophilic displacement of said groups by said anionic polymer; and
isolating the resulting biodegradable thermoplastic graft copolymer.
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Accused Products
Abstract
A nucleophilic displacement reaction is used to prepare biodegradable thermoplastic copolymers exhibiting a high capacity for stabilizing biodegradable blends of polysaccharides and synthetic thermoplastic polymers. The graft copolymers are characterized by consistent product uniformity and a high degree of substitution on the polysaccharide chain.
61 Citations
22 Claims
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1. Method for converting a polysaccharide to a biodegradable thermoplastic graft copolymer capable of forming homogeneous blends with synthetic thermoplastic polymers, said method comprising the steps of
chemically treating said polysaccharide to form on said polysaccharide nucleophilically displaceable groups at a substitution level of about 0.1 to about 0.75 nucleophilic displaceable groups per anhydroglucose unit of said polysaccharide; -
forming an anionic polymer of the formula ##STR4## wherein R1 is C1 -C6 alkyl or a group of the formula ##STR5## by (1) anionic polymerization of a compound of the formula R--CR═
CH2 and (2) treatment with a compound of the formula X═
C═
Z, wherein in the above formulas R and R'"'"' are independently hydrogen, C1 -C6 alkyl, phenyl, substituted phenyl or methoxycarbonyl;
X and Z are each independently O or S;
M+ is an alkali metal cation; and
n is an integer such that the group ##STR6## has a molecular weight between about 3000 and about 25,000;
reacting said anionic thermoplastic polymer with said polysaccharide-bearing nucleophilically displaceable groups under conditions conducive to nucleophilic displacement of said groups by said anionic polymer; andisolating the resulting biodegradable thermoplastic graft copolymer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. Method for converting a polysaccharide to a biodegradable thermoplastic graft copolymer capable of forming homogeneous blends with synthetic thermoplastic polymers, said method comprising the steps of:
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chemically treating said polysaccharide to form on said polysaccharide nucleophilically displaceable groups at a substitution level of about 0.1 to about 0.75 nucleophilically displaceable groups per anhydroglucose unit of said polysaccharide, said nucleophilic displaceable groups selected from the group consisting of halo, sulfonate, sulfate haloacetoxy, loweralkanesulfonyloxy benzylsulfonytoxy and arylsulfonyloxy; reacting said polysaccharide bearing nucleophilic displaceable groups with an anionic thermoplastic polymer carboxylate or thiocarboxylate under conditions conducive to nucleophilic displacement of said groups by said anionic carboxylate or thiocarboxylate; and isolating the resulting biodegradable thermoplastic graft copolymer characterized by uniformity of degree of polymerization of the grafted anionic polymer groups and a degree of substitution on the polysaccharide chain such that there is at least one anionic polymer group for every 15 to 50 anhydroglucose units in the polysaccharide. - View Dependent Claims (20, 21, 22)
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Specification