New ring-opening polymerizations for copolymers having controlled microstructures

Abstract

Various prestructured cyclic monomers were synthesized and polymerized to construct the copolymers of controlled mer sequence. Vinylcyclopropanes with substituents –CN, –CO 2R and –C 6H 5 were prepared and radically ring-opening polymerized in 1,5-fashion to obtain high molecular weight polymers. Anionic polymerization of these monomers gave 3,5-polymers with vinyl pendent group. 2-Phenyl-3-vinyloxirane polymerized radically by C–C scission. These polymerization behaviors of 3-membered ring compounds were attributed to the activation of C–C bonds by electronic “push–pull” mechanism. The Ziegler–Natta polymerization of substituted 1-phenyl-2-vinylcyclopropane resulted in the formation of polymers with trans double bond. 1-Vinylspiro-[2,5]octa-4,7-diene-6-ones and 2-vinyl-2′-methyl-spiro[cyclopropane-1,4′-(1′-naphthalenone)] were prepared and polymerized anionically. The facile polymerization of these monomers was interpreted to be driven by aromatization energy. Radical polymerization of 2-phenyl-1-vinylcyclobutane proceeded in mixed mode of ring-opening (73%) and vinyl (27%) polymerization. Alkyl α-cyanoacrylates reacted with vinyl ethers to form head-to-head [2+4] adducts which polymerized in turn to give alternating H–H copolymers of α-cyanoacrylates and vinyl ethers. The H–H polymers exhibited higher T g values than their corresponding H–T polymers. Vinyl ketones showed the same behavior to that of α-cyanoacrylates. Phenyl-substituted β-vinyl-β-propiolactones polymerized radically with CO 2 elimination and hydrocarbon polymers of mixed structures were obtained. 2-Methylene-4-phenyl-1,3-dioxolane was found to be very reactive polymerizing readily with radical initiators to give a linear aliphatic polyester. This polymer was considered difficult to prepare by ring-opening polymerization of lactone. The high polymerizability of this monomer was attributed to the stabilization of the propagating radical by phenyl group. Cationic polymerization of this monomer by iodine gave polymers of vinyl type. 4-Methylene-1,3-dioxolane-2-ones polymerized radically in vinyl fashion. Upon hydrolysis the polymer gave vinyl polymer with two geminal pendent groups, –OH and –CH 2OH. This polymer was amorphous and readily soluble in water. The adduct of vinyl methyl ketone with 4-methylene-2-phenyl-1,3-dioxolane was prepared. This adduct spirobicyclic monomer was found to polymerize cationically by double ring opening with 6.7% expansion of volume. 8-Methylene-1,4-dioxasprio[4,5]deca-6,9-diene was prepared and polymerized radically. In this polymerization the growing species was supposed to be alkoxy radical which was rarely reported. A series of cyclic sulfones with vinyl group at the α-position were synthesized and polymerized. 2-Vinylthiolane-1,1-dioxide, 2-vinylthiane-1,1-dioxide and 2-vinylthiepane-1,1-dioxide were prepared and polymerized radically. Among these sulfones 5-membered sulfone was only the monomer which polymerized cleanly via ring-opening. Disulfones were also prepared and found to polymerize well as expected. Ring-opening metathesis polymerization of properly substituted cyclooctenes were carried out with catalyst WCl 4(OAr) 2/SnBu 4 (OAr=2,6-diphenylphenoxy group) and the alternating terpolymers of butadiene–styrene–propylene, butadiene–styrene–ethylene and butadiene(1)–styrene(2). Polymerization of methyl 3,7-cyclodecadienecarboxylate gave the copolymer of butadiene and methyl acrylate in alternating fashion of 2 butadiene and 1 acrylate. Substituted 1,5-cyclo-decadienes were polymerized to obtain the alternating terpolymers of butadiene with various vinyl monomers. Vinylcyclopropanes with mesogenic groups as substituents were prepared and polymerized successfully. The resulting polymers with pendent mesogenic groups exhibited liquid crystalline properties. Mesogenic groups were cholesteryl and 6-(4′-cyano-4-biphenylyloxy)hexyl groups. Sequence-controlled copolymers of ethylene and vinyl alcohol were prepared by hydrogenation of the polymers obtained from acetoxy-cyclooctene, -cyclodecadiene and -cyclododecadiene. These copolymers were highly crystalline and exhibited the higher melting temperatures than their corresponding random copolymers. Polyethylene chain with pendent mesogenic 4′-methoxy-4-biphenyl terephthalate at every 12th carbon was synthesized and the liquid crystalline properties were observed.