Individual effective glass transitions of components in miscible blends of polystyrene/poly(vinyl methyl ether), poly(o-chlorostyrene)/poly(vinyl methyl ether), and poly(styrene-block-n-butyl acrylate)/polystyrene were detected by temperature-modulated differential scanning calorimetry. These blends apparently showed broad single glass transitions in their heat capacity (C p ) curves. This result has been widely accepted as a criterion of miscible mixing of both components. However, the derivative C p curves of some blends showed bimodal peaks. This indicates the coexistence of two relaxations in the miscible blend. Moreover, the ratio of the two peaks was related to the compositions of the blends. The temperatures at the peaks of the derivative C p curve were taken to be effective glass transition temperatures (T g,A and T g,B) of the components in the blend. T g,A and T g,B were much different from the average glass transition temperature (T g,av) at which the endothermic shift was half in the C p curve. On the other hand, T g,av and T g,A of homopolymers and poly(styrene-random-n-butyl acrylate)s were almost coincident with each other. T g,A and T g,B of the blends were in excellent agreement with the effective glass transition temperatures predicted by the model, taking into account the self-concentration effect.

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Summary: A cationic polymerization of isobutylene, isobutyl vinyl ether, ethyl vinyl ether, vinylcarbazole and α‐methylstyrene was induced by mixing with poly(vinylidene fluoride) (PVDF) powder. The polymerization was an exothermic reaction and gave a high yield. An electron was abstracted from the monomer by PVDF. By the abstraction of the electron, the monomer was converted to a cation radical which induced polymerization. The generation of the cation radicals of the vinyl ethers was confirmed by an ESR spin trapping method, although the cation radicals could be coupled immediately. The resulting polymer was isolated from PVDF (not grafted) and characterized by size exclusion chromatography, IR, UV‐Vis and NMR spectroscopy. The copolymerization of vinyl ethers or vinyl ether/vinylcarbazole was carried out successfully to obtain their random copolymer. PVDF is regarded as a reusable catalyst for cationic polymerizations.Reaction mechanism of the cationic polymerization of iBVE.magnified imageReaction mechanism of the cationic polymerization of iBVE.