Radical addition-fragmentation chemistry in polymer synthesis

Cyclic monomers bearing either vinyl or exomethylene groups have the ability to be polymerized through a radical pathway via a ring-opening mechanism (addition–fragmentation process), leading to the introduction of functionalities in the polymer backbone. Radical ring-opening polymerization (rROP) combines the advantages of both ring-opening polymerization and radical polymerization, that is the preparation of polymers bearing heteroatoms in the backbone but with the ease and robustness of a radical process. This current review presents a comprehensive description of rROP by detailing: (i) the various monomers that polymerize through rROP; (ii) the main parameters that govern the rROP mechanism; (iii) the copolymerization by conventional or controlled/living radical polymerization between rROP monomers and traditional vinyl monomers to obtain copolymers with advanced properties; (iv) the different applications (low shrinkage materials and preparation of (bio)degradable materials) of rROP monomer-containin...

Radical Ring-Opening Polymerization: Scope, Limitations, and Application to (Bio)Degradable Materials

Chemistry, chances and limitations of the radical ring-opening polymerization of cyclic ketene acetals for the synthesis of degradable polyesters

Polycaprolactone: Synthesis, Properties, and Applications

Aliphatic polyesters are important biodegradable polymers with wide applications. Polyesters prepared by ring-opening polymerization often have a limited range of properties, because of the minimal functional diversity of available lactone monomers. In this review, synthetic strategies in preparing functional lactone monomers are highlighted, as well as recent controlled polymerization strategies to synthesize functional aliphatic polyesters, which include proton-transfer polymerization, ring opening polymerization of O-carboxyanhydrides, radical ring-opening polymerization of cyclic ketene acetals, and copolymerization of epoxide/anhydride.

New Chemistry in Functional Aliphatic Polyesters

Since free radical ring-opening polymerization made it possible to introduce functional groups, such as esters, carbonates, thioesters, and amides, into the backbone of an addition polymer, it was reasoned that simple hydrolysis of these copolymers would produce the desired oligomers that could be terminated with various combinations of hydroxyl, amino, thiol, and carboxy1 groups. Thus the copolymerization of 2-methylene-1,3-dioxepane and styrene (r1=0.021 and r2=22.6) gave a copolymer containing 10 mole-percent of an ester-containing unit with 100% ring opening at 120°C. Hydrolysis of this copolymer gave an oligomer terminated with a hydroxyl group and a carboxylie acid group. Similarly the copolymerization of 2-methylene-1,3-dioxepane and ethylene gave a series of biodegradable polyethylene copolymers containing 2.1 to 10.4% ester-containing units. Hydrolysis of these copolymers gave a series of ethylene oligomers with nine to forty-seven ethylene units and terminated with a hydroxyl group and ...

Takashi Endo

Papers

Synthesis of functionally-terminated oligomers by free radical ring-opening polymerization