Hemisilicone Elastomers That Are Recyclable to the Monomer

Abstract

Methyl-, vinyl-, and hydride-terminated polymers of the heterocyclic monomer, 2,2,5,5-tetramethyl-2,5-disila-1-oxacyclopentane (c-M 2 E) were prepared by sulfuric acid-catalyzed, ringopening equilibration with the end-capping agents hexamethyldisiloxane (MM), divinyltetramethyldisiloxane (M V M V ), and tetramethyldisiloxane (M H M H ), respectively. The molecular weights of the polymers were controlled by adjusting the ratio of monomer to end-capping agent. All of these polymers are oils and exhibit molecular weight-dependent viscosities that are qualitatively similar to those of polydimethylsiloxane (PDMS)-based analogs prepared by the same reaction using octamethylcyclotetrasiloxane (D 4 ) instead of c-M 2 E. Vinyl end-capped polymers with a range of molecular weights were cross-linked by platinum-catalyzed hydrosilylation with tetramethylcyclotetrasiloxane (D H 4 ) to prepare a series of transparent solid elastomers with moduli that increase with decreasing molecular weight. These studies suggest that reactive polymers prepared from c-M 2 E may be useful resins in two-part curable elastomer formulations. Several experiments, as well as the over 60-year-old initial synthesis of this polymer, suggest that the recyclability of these resins and elastomers may be practical.

Naphthalene engineering of chemically recyclable polyesters with enhanced thermal and mechanical properties

“…13–15 Advances in monomer design have led to the development of a diverse assortment of polymer systems that are capable of undergoing ring-opening polymerization (ROP) and subsequently chemical recycling to monomers. 16–42 Furthermore, monomer structure modification has emerged as an essential tool for tuning the thermal and mechanical properties of the resulting polymers. 43–45…”