Multiphase block and graft copolymers comprising a hydrophilic continuous phase and hydrophobic domains
First Claim
1. A method of promoting the survival and growth of plants which comprises admixing with the plant growth medium in which said plants are grown from about 25 weight percent of a thermoplastic copolymer having an average molecular weight of at least 10,000, selected from the group consisting of copolymers represented by graph copolymers having the general formula ##STR9## and block copolymers having the general formula xB--[AB]n --yA wherein n is an integer ≧
- 1, m is >
1, x and y are 0 or 1, and y is 1 when n is 1, A is a thermoplastic hydrophobic polymer block having a softening point of at least 35°
C and a molecular weight of at least 2,000, and B is a thermoplastic hydrophilic polymer block having a softening point of at least about 35°
C and a molecular weight of at least about 6,000 and which comprises from about 30-97 weight % of said copolymer.
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Abstract
This invention relates to thermoplastic, multiphase copolymers selected from the group consisting of copolymers represented by graft copolymers having the general formula ##STR1## AND BLOCK COPOLYMERS HAVING THE GENERAL FORMULA XB--[AB]n --yA wherein n is an integer ≧ 1, m is > 1, x and y are 0 or 1, and y is 1 when n is 1, A is a thermoplastic, hydrophobic polymer block having a softening point (i.e., a glass transition or cyrstalline melting point) of at least 35° C and a molecular weight of at least 2,000, and B is a thermoplastic, hydrophilic polymer block having a softening point of at least about 35° C and a molecular weight of at least about 6,000, which comprises from about 30-97 wt % of said copolymer. The novel polymers of this invention are useful for making water containing gels. Preferably, the thermoplastic multiphase copolymer is a styrene-ethylene oxide copolymer. The novel polymers are made by a process which allows one to prepare a copolymer which is substantially free of homopolymeric impurities. The compositions of the instant invention are melt processable by conventional thermoplastic techniques.
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Citations
9 Claims
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1. A method of promoting the survival and growth of plants which comprises admixing with the plant growth medium in which said plants are grown from about 25 weight percent of a thermoplastic copolymer having an average molecular weight of at least 10,000, selected from the group consisting of copolymers represented by graph copolymers having the general formula ##STR9## and block copolymers having the general formula xB--[AB]n --yA wherein n is an integer ≧
- 1, m is >
1, x and y are 0 or 1, and y is 1 when n is 1, A is a thermoplastic hydrophobic polymer block having a softening point of at least 35°
C and a molecular weight of at least 2,000, and B is a thermoplastic hydrophilic polymer block having a softening point of at least about 35°
C and a molecular weight of at least about 6,000 and which comprises from about 30-97 weight % of said copolymer. - View Dependent Claims (2, 3, 4, 5)
- 1, m is >
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6. An improved method of planting agricultural seeds in a plant growth medium in which said seeds will germinate, said seeds being disposed within a polymeric tape, said tape being placed within said plant growth medium, wherein the improvement comprises forming said tape from a thermoplastic copolymer having an average molecular weight of at least 10,000, selected from the group consisting of copolymers represented by graph copolymers having the general formula ##STR10## and block copolymers having the general formula xB--[AB]n --yA wherein n is an integer ≧
- 1, m is >
1, x and y are 0 or 1, and y is 1 when n is 1, A is a thermoplastic hydrophobic polymer block having a softening point of at least 35°
C and a molecular weight of at least 2,000, and B is a thermoplastic hydrophilic polymer block having a softening point of at least about 35°
C and a molecular weight of at least about 6,000 and which comprises from about 30-97 weight % of said copolymer, whereby said polymer absorbs and retains water thereby forming a water swollen tape disposed in said plant growth medium for improving said germination of said seeds. - View Dependent Claims (7, 8, 9)
- 1, m is >
Specification