A model graft copolymer that has well-defined length, number, and position of grafts was prepared via anionic living polymerization. (4-Vinylphenyl)dimethylvinylsilane (VS) was anionically polymerized by cumylcesium in THF at -78°C for 20 min under a pressure of 10 -5 mmHg, and subsequent addition of styrene (St) yielded a PVS-b-PSt block copolymer that could be used as a backbone molecule. PVS has a silylvinyl group on the side chain that converts chemical links between backbone and grafts. Isoprene (Is) was anionically polymerized to yield living polyisoprene, and the resultant PIs -Cs + and PIs -Li + solutions were added to THF and benzene solutions of PVS-b-PSt, respectively. After 24 h, backbone coupling was terminated to yield [poly((4-vinylphenyl)dimethylvinylsilane)-graft-polyisoprene]-block-polystyrene. The three graft copolymers were prepared. Molecular characterization was carried out by GPC measurement, osmometry, and sedimentation pattern. The Mn and Mw/Mn values of the backbone, grafts, and graft copolymers were determined. The number of grafts per backbone molecule was found to be 10.0, 10.9, and 12.5 for the three graft copolymers, and the position of the grafts was set to the end of the backbone molecule. Spacing and its distribution of the graft points on a backbone molecule were also discussed. Three benzene-cast films formed clear microphase-separated structures, such as spherical and lamellar structures. The composition dependence on the morphology of the graft copolymers was found to differ from that of common block copolymers. These results suggest that the apparent volume fraction of grafts is much larger than the real volume fraction, because the grafts became crowded in the vicinity of the backbone molecule.

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ABSTRACT:The polymers of three tertiary aminostyrenes: poly(N,N-dimethyl-4-vinylphenylamine), abbreviated as PPA; poly(N,N-dimethyl-4-vinylbenzylamine), PBA; and poly-(N,N-dimethyl-4-vinylphenethylamine), PPTA, were prepared via anionic polymerization in THF at -78°C. GPC measurement was carried out to estimate the molecular weights and molecular weight distributions (MWD) of the polymers. A mixture of THF and Nmethylpyrrolidine (2 v/v%) was used as carrier solvent to avoid the adsorption of the polymers on the surface of the GPC gels. When n-butyllithium was used as an initiator, 100% polymer conversion was attained. The values of Mw/Mn were more than 1.20. The M. was equal to Mk, calculated from the amounts of monomers and initiators. No polymer having narrow MWD was obtained, even when N-methylpyrrolidine was used as an additive. On the other hand, when cumyl potassium and cumyl cesium were used as initiators, polymers having narrow MWD were produced. The values of M w! Mn were less than 1.08. The apparent rate constant of polymerization of cumyl cesium for PPA was small, compared with those for PBA and PPT A.

Films prepared from poly(isoprene-b-styrene-b-isoprene-b-(4-vinylbenzyl)dimethylamine-i>isoprene) (ISIAI) pentablock copolymers were subjected to chemical modification: the A block was quaternized, the I block cross-linked, and the S block sulfonated, in that order. The three-layer lamellar structures of the original films were retained through these processes. The resulting membranes had substantial cationand anion-exchange capacities and cation transport numbers near 0.50 for KC1. They exhibited a piezodialytic effect and negative osmosis as predicted for a "charge-mosaic" membrane.

The dielectric properties of poly(ethylene oxide) (PEO) were examined for 10 samples ranging in molecular weight, M, from 190 to 2 x 10 6. Two dielectric relaxations were observed. The one observed at high temperature and low frequency is called a process, and the other at low temperature and high frequency is called {3 one. The {3 process is due to the local motion of amorphous PEO segments, and has a loss maximum temperature, T maxo and an apparent activation energy, E., independent of either M or degree of crystallinity, Xc. On the other hand, the a process, which is due to a large scale conformational rearrangement of amorphous PEO segments, is dependent on both M and Xc. The relaxation strength and T max vary with Xc, while the E. and the relaxation width do not depend on Xc but exhibit an abrupt increase at M of about 10 4 • These results may be due to change not only in Xc but also in the crystalline morphology with M.