Preparation, characterization, and nanophase-separated structure of catenated polystyrene-polyisoprene

A catenated copolymer consisting of cyclic polystyrene (PS) with short poly(2-isopropenylnaphthalene) (PIPN) segments and cyclic polyisoprene (PI) were prepared by living anionic polymerization. The molecular weight of catenated copolymer is 37 kDa. Naphthalene side groups attached to the PIPN segments in the cyclic P(IPN-b-S) were radical-anionized by a reaction with potassium in THF, and telechelic PI was successfully cyclized by a pair of coupled reactions at two close radical-anionized sites on the cyclic chain under dilute conditions. Formation of the catenated copolymer consisting of cyclic P(IPN-b-S) and cyclic PI was confirmed by size-exclusion chromatography using a UV detector with a wavelength of 320 nm for preferential detection of naphthalene moieties. After isolation of the catenated copolymer by fractionation, it was confirmed by transmission electron microscopy that the topologically linked polymers exhibit a nanophase-separated structure in bulk.