From Octamethylcyclotetrasiloxane to Reprocessable and Recyclable Networks of Polydimethylsiloxane via One-Pot Reactions.

Abstract

Polydimethylsiloxane (PDMS) networks were generated with octamethylcyclotetrasiloxane (D4) and 1,4-bis(heptaisobutylPOSS)dipropoxybutane (denoted diPOSS) via a one-pot reaction approach, which was mediated with tetrabutylammonium fluoride (TBAF). The reaction involving the formation of PDMS networks included: (i) the fluoride-initiated anionic ring-opening polymerization (ROP) of D4, and (ii) the rearrangement of siloxane. By varying the feed ratios of D4 to diPOSS, the PDMS-POSS networks were obtained with variable crosslinking densities, having tunable thermal and mechanical properties. Benefiting from the incorporation of TBAF, the crosslinked networks can be reprocessed without sacrificing their mechanical strengths. Furthermore, the PDMS-POSS networks can be depolymerized into oligomeric siloxanes with the aid of a polar solvent (i.e., tetrahydrofuran). Upon removing the solvent, the networks can be regenerated with the reverted mechanical strengths.