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

This chapter deals with radical ring-opening polymerization (radical ROP), which provides us with a strategy for synthesizing heteroatom-containing polymers by radical processes. Various cyclic monomers capable of radically induced ROP are introduced so that the essential items of molecular designs and polymerization mechanisms can be understood. Recent examples of controlled radical ROPs for well-defined polymer synthesis are also described.

Radical ring-opening polymerization

A series of functionalized poly(e-caprolactone) copolymers, poly(e-caprolactone-co-vinylphosphonic acid) and poly(e-caprolactone-co-dimethyl vinylphosphonate), were synthesized by the free-radical copolymerization of 2-methylene-1,3-dioxepane with two vinyl monomers, vinylphosphonic acid and dimethyl vinylphosphonate. The copolymers have ester groups in the backbone as well as pendant functional groups. The structure of each copolymer was established by 1H and 13C NMR as well as IR spectroscopy. Differential scanning calorimetry indicated that the copolymer had a random structure. NMR study showed hydrogen transfer during the copolymerization. The copolymers have different solubility behavior due to the presence of different pendant functional groups.

Synthesis and Characterization of Functionalized Poly(ε-caprolactone) Copolymers by Free-Radical Polymerization

A Study of the Mechanism of the Free-Radical Ring-Opening Polymerization of 2-Methylene-1,3-dioxepane

Copolymerization behavior of 5,6-benzo-2-methylene-1,3-dioxepane (BMDO) with styrene (St) is studied using benzyl bromide/CuBr/1,1,4,7,7-pentamethyldiethylenetriamine radical initiating system. Structural characterization of copolymers was done using 1D and 2D NMR techniques. The copolymer compositions were obtained from 1H NMR spectroscopy. The reactivity ratios for the copolymerization of BMDO with St were determined using Kelen−Tudos method and was found to be rBMDO = 1.08 and rSt = 8.53. Degradation behavior of the copolymers is also reported.

Synthesis and characterization of copolymers of 5,6-benzo-2-methylene-1,3-dioxepane and styrene

2-Butyl-7-methylene-1,4,6-trioxaspiro(4,4)nonane (7) was prepared by the reaction of 2-(bromomethyl)-5-oxo-tetrahydrofuran with 1,2-epoxyhexane, followed by dehydrobromination. Compound 7 could be polymerized by free radical initiators to give a viscous polymer. The IR and NMR spectra of the polymers indicated that the polymer structure contained ester and ketone units in the backbone, and a cyclic acetal side chain. Compound 7 readily copolymerized with acrylonitrile in the presence and absence of radical initiators, but did not copolymerize well with styrene. Ultraviolet spectra suggest that the spontaneous polymerization proceeds via a chargetransfer complex between 7 as an electron donor and AN as an electron acceptor.

Yin Wang

Papers

Synthesis and polymerization of 2‐butyl‐7‐methylene‐1,4,6‐trioxaspiro(4,4)nonane