Free-radical ring-opening polymerization polymers

Bailey WJ (1985) Free-radical ring-opening polymerization. Polym J 17 85-95... 

Since it was shown that free radical ring-opening polymerization (2) made it possible to introduce functional groups, such as esters C3j, carbonates (4), thioesters (5), and amides (6), into the backbone of an addition polymer, it was reasoned that simple hydrolysis would produce the desired oligomers that could be terminated with various combinations of hydroxyl, amino, thiol, and carboxylic acid groups. 

This indicates the possibility of making addition polymers biodegradable by the introduction of ester linkages in to the backbone. Since the free radical ring-opening polymerization of cyclic ketene acetals, such as 2-methylene-1,3-dioxepane (1, Scheme I), made possible the introduction of ester groups into the backbone of addition polymers, this appeared to be an attractive method for the synthesis of biodegradable addition polymers. 

Bailey WJ, Ni Z, Wu S-R (1982) Synthesis of poly-e-caprolactone via a free radical mechanism. Free radical ring opening polymerization of 2-methylene-l,3-dioxepane. J Polym Sci A Polym Chem 20 3021-3030... 

The above examples of free-radical ring-opening polymerization, which have been explored by Bailey and Endo, produce polymers containing ketonic carbonyl and/or ester groups in the main chain. In addition, these cyclic monomers can be copolymerized with vinyl monomers by free-radical mechanism. Thus, the variety of the polymers produced by radical polymerization has been enlarged. 

Free-radical ring-opening polymerization, in Contemporary Topics in Polymer Science, Vol. 3, M. Shen (ed.). Plenum, New York, 1979. 

It was also reported recently that a controlled free-radical ring-opening polymerization and chain extension of the living polymer was achieved in a polymerization of 2-methylene-1,3-dioxepane in the presence of 2,2,6,6-tetramethyl-l-piperidinyloxy free radical (TEMPO) [232] The reaction was initiated with di-ferf-butyl peroxide at 125°C... 

The Use of Free Radical Ring-Opening Polymerization to Produce Biodegradable Polymers... 

In this review the polymerization of formaldehyde, h her aliphatic aldehydes and haloaldehydes will be discussed with particular emphasis on the kinetics of the polymerization. As will be apparent the kinetics of aldehyde polymerization have not been studied as extensively as the kinetics of more conventional polymerizations, for example, the free radical bond opening polymerizations of styrene, vinyl chloride or methylmethacrylate or the ring opening polymerizations of tetrahydro-furan or ethylene oxide. One reason is that polyoxymethylene is the only polyaldehyde produced commercially and much of our knowledge on formaldehyde polymerization is proprietary information. Another is that the polymerization systems are very complex and the polymers precipitate during polymerization. 

Liu, Y., Ying, S., and Wan, X. (1999). Synthesis of block copolymers via transformation of living free radical polymerization into living cationic ring-opening polymerization. Polym. 

Ring-opening polymerization is an important field of research in the chemistry of polymer synthesis. Usually, it proceeds by ionic mechanisms, i.e. cationic, anionic and coordinate anionic mechanisms. Research on ring-opening polymerization proceeding via free-radical propagating species in which the so-called molecular design of monomer plays an important role has recently been reported. 

Poly(s-caprolactone) Poly(e-caprolactone) is a semicrystalline polymer synthesized by anionic, cationic, free-radical, or ring-opening polymerization [94]. It is available in a range of molecular weights and degrades by bulk hydrolysis autocatalyzed by the carboxylic acid end groups. The presence of enzymes such as protease, amylase, and pancreatic lipase accelerates polymer degradation [95], The various methods of preparation of poly(e-caprolactone) nanoparticles include emulsion polymerization, interfacial deposition, emulsion-solvent evaporation, desolvation, and dialysis. These methods and various applications are extensively reviewed [94],... 

Besides some particular cases such as ozonolysis2,3) or ring-opening polymerization of ketene-acetal type monomers4), the hydroxytelechelic polymers can be synthesized also by anionic polymerization. This process leads to polymers with smaller polydispersity and to a theoretical functionality of two free-radical polymerizations are easier to carry out, cheaper and, therefore, of industrial importance. Several reviews deal with the synthesis of functionally terminated polymers s>6 7, while this paper concerns only radical processes leading to hydroxytelechelic polymers. 

Transition metal catalyzed, ring opening polymerization Dispersion, cationic polymerization Homogeneous/precipitation, cationic polymerization Homogeneous, free radical/cationic polymerization Precipitation, free radical polymerization Dispersion, free radical polymerization Norbornene polymer, polycarbonate Isobutylene polymer Vinyl ether polymer Amorphous fluoropolymers Vinyl polymer, semicrystalline fluoropolymers Polyvinyl acetate and ethylene vinyl acetate copol5Tner... 

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