STUDY OF SEMICRYSTALLINE-AMORPHOUS DIBLOCK COPOLYMERS .1. MICROPHASE SEPARATION, GLASS-TRANSITION AND CRYSTALLIZATION OF TETRAHYDROFURAN METHYL-METHACRYLATE DIBLOCK COPOLYMERS

The microphase separation, glass transition and crystallization of two series of tetrahydrofuran-methyl methacrylate diblock copolymers (PTH F-b-PMMA), one with a given PTHF block of M(n) = 5100 and the other wi th a given PTHF block of (M) over bar(n) = 7000, were studied in this present work. In the case of solution-cast materials, the microphase s eparation of the copolymer takes place first, with crystallization the n gradually starting in the formed PTHF microphase. The T-g of the PMM A microphase shows a strong dependence on the molecular weight of the PMMA block, while the T-g of the PTHF microphase shows a strong depend ence on the copolymer composition. The non-isothermal crystallization temperature (T-c) of the diblock copolymer decreases rapidly and conti nuously with the increase in the amorphous PMMA weight fraction; the l owest T-c of the copolymer is ca. 35 K lower than the T-c of the PTHF homopolymer. There also exists a T-c dependence on the molecular weigh t of the PTHF block. In addition, when the major component of the copo lymer is PMMA, a strong dependence of the crystallizability of the cop olymer on the molecular weight of the PTHF block is observed; the high er the molecular weight, then the stronger its crystallizability. The melting temperature of the block copolymer is dependent on the copolym er composition and the molecular weight of its crystallizable block. C opyright (C) 1996 Elsevier Science Ltd.