Chain Transfer by the Addition-Fragmentation Mechanism. 6. Radical Polymerization toward the Synthesis of End-Functional Telomers, Macroinitiators, and Block Copolymers

Abstract

Acetal-or peroxyketal-terminated oligomers were prepared via a powerful process and characterized. Methanolysis of alkoxy(oxiranyl)-terminated or peralkoxy(oxiranyl)-terminated precursors were used to obtain the desired structures through an addition-substitution evolution on new chain transfer agents, 3-(cumylperoxy)-3-OY-2-phenyl-1-propene (see Chart 1) with Y ) Me (CPMPP), Y ) Et (CPEPP), and Y ) OCMe2Ph (dCPPP). The free radical polymerization of methyl methacrylate (MMA), styrene (St), and methyl acrylate (MA) in the presence of such peroxyketals and precipitation of the polymer in methanol afforded directly the end-functional polymers. Chain transfer constants (Ctr) for these compounds in the monomer polymerization at 60°C were determined from measurements of degrees of polymerization. Ctr values for CPMPP were determined to be 0.49, 0.92, and 1.94 in MMA, St, and MA, respectively. CPMPP behaves as an ideal transfer agent for styrene at temperatures close to 60°C. The chain transfer activation energies, Ea,tr, for the reactions of PS and PMMA radicals with CPMPP were estimated to be 46.0 and 12.4 kJ‚mol -1 , respectively. The thermolysis activation energies of these peroxyketals, Ea,th ) 134.7 and 127.7 kJ‚mol -1 , respectively, to CPMPP and dCPPP were calculated from the Arrhenius plot of the homolytic decomposition rate constants, kth, at various temperatures. dCPPP was used to design a monofunctional macroinitiator, a precursor of diblock copolymers.

A kinetic study on polymerization of methyl methacrylate with di-t-butyl perfumarate

“…Recently, t ‐alkyl permethacrylates3 and related monomers5–8 have been observed to serve as chain transfer reagents via an addition–substitution mechanism.…”

Synthesis of heterotelechelic polymers by free radical addition-fragmentation chain transfer

“…Polymers P6c, d were easily obtained by precipitation of the corresponding x-(alkoxyoxiranyl) polystyrenes P6a and P6b in methanol [20], owing to the good reactivity of the alkoxyoxirane ring with hydroxylated substances. The latter oligomers were used further to initiate free radical polymerization of MMA in order to prepare diblock copolymers [20].…”

“…The latter oligomers were used further to initiate free radical polymerization of MMA in order to prepare diblock copolymers [20].…”

Visible‐light‐induced controlled/living radical polymerization of styrene with a phenyl seleno group at one terminal chain end: 1‐(Phenylseleno)ethyl benzene as a photoiniferter

“…The synthesis of end-functional polymers by living radical polymerization with an iniferter is requisite and convenient and hence is widely used. 18,19 Organoselenium compounds are useful for synthetic chemistry 20 and photochemistry. 21,22 Kwon et al 23 reported that photopolymerization in the presence of diphenyl diselenide (DPDS) afforded polystyrene carrying phenylseleno groups at both chain ends.…”

“…An iniferter is an initiator that also functions as a chain‐transfer radical terminator, a primary radical terminator, or both. The synthesis of end‐functional polymers by living radical polymerization with an iniferter is requisite and convenient and hence is widely used 18, 19…”