Preparation, purification and use of high-X diblock copolymers
View Patent ↗This invention relates to the preparation and purification of high-X (“chi”) diblock copolymers. Such copolymers contain two segments (“blocks”) of polymers with significantly different interaction parameters and can be used in directed self-assembly applications.
1. A process for purifying a crude diblock copolymer composition comprising:
a) forming in a first solvent a polymer mixture comprising a diblock copolymer, poly(Monomer 1)-b-poly(Monomer 2), and at least one homopolymer selected from poly(Monomer 1) and poly(Monomer 2);
b) adding a second solvent to the polymer mixture to form:
micelles comprising the diblock copolymer and
a solution comprising at least one of poly(Monomer 1) and poly(Monomer 2);
c) inducing micellar aggregation to form isolable particles; and
d) separating the particles from the solution that comprises at least one of poly(Monomer 1) and poly(Monomer 2), whereby said isolable particles contain the purified diblock copolymer;
wherein said diblock copolymer composition comprises:
i) a first block derived from the polymerization of Monomer 1,
wherein X is H or methyl, R is selected from the group consisting of: C 1 -C 8 alkyl and partially fluorinated alkyl groups, optionally substituted with hydroxyl or protected hydroxyl groups; and C 3 -C 8 cycloalkyl groups; and
ii) a second block covalently attached to the first block, wherein the second block is derived from the polymerization of Monomer 2,
wherein Ar is a pyridyl group, a phenyl group, or a phenyl group comprising substituents selected from the group consisting of hydroxyl, protected hydroxyl, acetoxy, C 1 -C 4 alkoxy groups, phenyl, substituted phenyl, —SiR′ 3 , and —OC(O)OR′, where R′ is selected from the group consisting of C 1 -C 8 alkyl groups.
2. The process as set forth in claim 1 wherein Monomers 1 and 2 are selected such that the difference between the surface energy values of a homopolymer of Monomer 1 and a homopolymer of Monomer 2 is greater than 10 dynes/cm.
3. The process as set forth in claim 1 wherein the first block comprises 5-95 wt % of the diblock copolymer.
4. The process as set forth in claim 1 wherein the molecular weight of the purified diblock copolymer is between 10,000 and 250,000.
5. The process as set forth in claim 1 wherein the purified diblock polymer comprises less than 5 wt % of the homopolymer of Monomer 1 and less than 5 wt % of the homopolymer of Monomer 2.
6. The process as set forth in claim 5 wherein Monomer 1 is methyl methacrylate and Monomer 2 is styrene.
7. The product produced by the process of claim 6 .