Importance

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Abstract

There is disclosed a process for selectively cyclizing block polymers which comprises reacting 1 to 30 percent by weight solution of a block copolymer comprised of at least two different blocks, at least one of which blocks is a cyclizable block derived from a conjugated diene monomer of the general structure ##STR1## wherein: R.sub.1 is selected from a hydrocarbyl group containing one to twelve carbon atoms, R.sub.2 is selected from hydrogen or a hydrocarbyl group containing one to twelve carbon atoms; and at least one of which blocks is a non-cyclizable block derived from at least one member selected from the following classes of compounds: (a) polymers of conjugated diene monomers of general structure ##STR2## wherein: R.sub.3, R.sub.4 and R.sub.5 are the same or different and are selected from hydrogen or a hydrocarbyl group containing one to twelve carbon atoms; R.sub.6 is selected from hydrogen, a hydrocarbyl group containing one to twelve carbon atoms or a cyano group, (b) polymers of .alpha.-methylstyrene, styrene, alkyl or aryl substituted styrenes or halogen substituted styrenes, (c) polymethacrylonitrile, polycaprolactam, polycaprolactone or polydimethylsiloxane, with a cationic catalyst at concentrations from about 0.1 to about 20 parts by weight per hundred parts by weight of said block copolymer at a temperature of about 0.degree.-200.degree. C. for a reaction time ranging from 0.2 to 25 hours and stopping the reaction, said cyclized blocks constituting about 5-95 weight percent of cyclized block copolymer and said non-cyclized blocks constituting about 95-5 weight percent of cyclized block copolymer.

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First Claim