LAUSR

Abstract In this study, we reported a convenient pathway toward the molecular design of double network materials. First, we prepared an ABA-type copolymer composed of a central poly (n-butyl acrylate) block and two 4-vinylpyridine end moieties, i.e., 4VP-PnBA-4VP. Since the central PnBA block was much larger than the two end 4VP blocks, sphere 4VP domains were formed in the PnBA matrix after the phase segregation. Second, we introduced a small number of polyoxometalate (POM) molecules that preferentially locate in the 4VP domain to cross-link only a fraction of the end moieties selectively. Since the cross-linked ends have an additional association energy, the sample exhibits two-step relaxation behavior. The amplitude and relaxation time of the slower process, owing to those chains end-cross-linked by POM, can be well explained by assuming (1) the reactivity is the same for all chain ends during the synthesize of the the end moiety, and (2) the probability for crosslinking by POM is the same for all 4VP monomers in their domain.