Cationic copolymerization of methyl glyoxylate with 1,3-dioxolane

Cationic copolymerization of methyl glyoxylate (GM), an aldehyde containing an ester group in addition to aldehyde function, with cyclic acetal, 1,3-d ioxolane (DXL), was studied. Resulting copolymers after hydrolysis of the e ater groups provide hydrophilic, degradable polymers containing ionic funct ions. It has been shown that despite the reversibility of homopropagation s teps for both comonomers the conversion of both comonomers in copolymerizat ion can be nearly quantitative. Molecular weights of copolymers are relativ ely high (up to 1.7 x 10(4)), although lower than that calculated for polym erization proceeding without transfer. It Nas established that chain transf er involves hydride ion abstraction from the GM monomer or from the GM repe ating unit of the copolymer. Polymerization is accompanied by extensive cha in transfer to polymer (transacetalization). Intramolecular reaction (backb iting) leads to formation of a cyclic fraction, of which the major componen t (the only one observed) is a heterodimer, in other words, a seven-membere d cyclic acetal composed of one GM and one DXL unit. Intramolecular chain t ransfer to the polymer leads to redistribution of comonomer units, and copo lymers having nearly random distribution are formed (with a slight tendency for alternation due to the steric repulsion between bulky substituents in the GM-GM homodiads).