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Efficient syntheses of the triblock copolymer styrene‐ b ‐tetrahydrofuran‐ b ‐styrene by coupling of preformed blocks
Author(s) -
Chien James C. W.,
Hong JinLong,
Lillya C. Peter
Publication year - 1990
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1990.070410324
Subject(s) - tetrahydrofuran , copolymer , polystyrene , styrene , polymer chemistry , materials science , glass transition , gel permeation chromatography , diphenylmethane , polymer , organic chemistry , chemistry , composite material , catalysis , solvent
The triblock copolymer styrene‐ b ‐tetrahydrofuran‐ b ‐styrene was prepared from commercially available hydroxyl‐terminated poly(tetrahydrofuran), M n = 1,650 and mono‐hydroxyl‐terminated polystyrene, M n = 7,600. Poly(tetrahydrofuran) blocks were first chain extended by reaction by with 1.1 equivalents 4,4′‐diphenylmethane diisocyanate (MDI) and subsequently end capped with 20% excess of hydroxyl‐terminated polystyrene. Gel permeation chromatography revealed clearly the success of the end capping step to give triblock copolymer mixed with a small amount of excess polystyrene. 1 H NMR revealed a gross composition by weight of 50% styrene, 41% tetrahydrofuran, and 9% MDI. DSC revealed a 5°C elevation of the PTHF glass transition and a 15°C lowering of PS glass transition temperature as compared with those of the individual component blocks. These values along with behavior of films as a tough elastomer are consistent with triblock structure and microphase separated morphology. The polymer does not flow readily below 125°C which is well above T g of the polystyrene domains.