Partially Bio-Based and fluorinated polysiloxane with high transparency and low dielectric constant

Abstract

Bio-based polymers with unique properties have attracted much more attention nowadays because of the increasing sustainable development aspirations. In this study, bio-based siloxane precursors functionalized with multiple trifluorovinyl-ether (TFVE) groups were successfully synthesized through facile derivation from renewable eugenol. Firstly, eugenol was converted into a TFVE-functionalized monomer (1). Then, hydrosilylations between monomer 1 and commercially available hydrosiloxanes were performed to prepare fluorinated siloxanes with various functionalities. Polymerization steps were realized to prepare fluorinated linear M−PFCB and crosslinked D4-PFCB connected by perfluorocyclobutyl (PFCB) groups via the [2π+2π] thermal addition between TFVE groups, which occurred through an environment-friendly process without any catalysts or solvents. Due to the coexistence of siloxane segments and PFCB linkers, both polysiloxanes exhibited excellent transparency. In particular, the crosslinked D4-PFCB showed good thermostability with a 5 wt% loss temperature of 403 °C. Furthermore, presence of PFCB segments in D4-PFCB also resulted in the high hydrophobicity and low dielectric constant. Especially, D4-PFCB exhibited a low dielectric constant of 2.60 at 12 GHz, indicating its potential application in the encapsulation fields.