Cationic equilibrium ring‐opening polymerization of bicyclic monomers and its application to chemical recycling

Abstract

SUMMARYSpiro orthoesters give poly(cyc1ic 0rthoester)s by single ring-opening polymerization in the presence of acid catalysts, and this process undergoes the equilibrium polymerization. We have applied the function of equilibrium polymerization to chemical recycling of polymeric materials. Crosslinked poly(cyc1ic orthoester)s, prepared by radical additions of poly(cyc1ic 0rthoester)s possessing exomethylene groups and dithiols, efficiently decrosslinked to bifunctional spiro orthoesters in the presence of CF3C0,H in CqCl,. The dithiol-linked bifunctional spiro orthoester monomers, prepared by the radical additions of spiro orthoester possessing exomethylene group and dithiols, afforded the corresponding crosslinked polymers in the presence of CF3C0,H as a catalyst in bulk. The decrosslinking of the obtained crosslinked polymer proceeded quantitatively to obtain the corresponding bifunctional monomer at room temperature in CH& Further, an acid-catalyzed reversible crosslinking-decrosslinking of a polymer having a spiro orthoester group in the side chain was carried out. The copolymer obtained by the radical copolymerization of 2-methylene-l,4,6-trioxaspiro[4.6]undecane with acrylonitrile was treated with CF3C0,H at -10 "C in CH,C1, to afford the crosslinked polymer quantitatively. The crosslinked polymer was then treated with CF3C02H at room temperature at a low concentration in CH,Cl, to recover the original polymer. IntroductionDevelopment of an excellent method for recycling of polymeric materials is an extremely important subject in recent polymer science and technology.') Among the few technologies for recycling, chemical recycling may be the most important and essential. Spiro orthoesters (SOEs) polymerize with cationic catalysts to yield poly(ether-ester)s via double ring-opening polymerization (Scheme 1);) and no shrinkage in volume is observed on this polymerization. This may be explained by the compensation effect by the double ring-opening in the decrease in free volume due to nearing molecules from van der Wads distance to covalent distance. Recently, we have found that SOE (1) polymerizes with Al(acac), as a catalyst at room temperature to give poly(cyc1ic orthoester) (2) which can be regarded as being formed via a selective single ring-

Thermal dissociation behavior of polymers with hemiacetal ester moieties in the side chain: The effect of structure on dissociation temperature

“…Chloro-benzene was washed with concentrated H 2 SO 4 and then with aqueous NaHCO 3 and water, dried over CaCl 2 and then over P 2 O 5 , and distilled. All the monomers were prepared by the previously reported procedures with slight modification.…”

“…They frequently are seen in the design of initiators, dormant species, and active sites on reactive polymers. Homolytic/heterolytic cleavage of such covalent bonds triggered by external stimulation is one of the focal points of current research related to the recent development of a stable free-radical polymerization, 1 a non-salttype latent initiator in cationic polymerization, 2 resist materials, 3 a polymer recycling system, 4 and so forth. The cationic addition reaction of vinyl ether with alcohol or carboxylic acid produces acetal or hemiacetal ester as well as a polymerization reaction.…”