Incorporating a silicon unit into a polyether backbone—an effective approach to enhance polyether solubility in CO2

Abstract

A series of poly(silyl ether)s were prepared by condensation polymerization and hydrosilation polymerization through incorporating a silicon unit into a polyether backbone. The phase behavior of poly(silyl ether)s in CO₂ was measured in terms of concentration, molecular weight and temperature. Through incorporating the silicon unit, the poly(silyl ether)s exhibited high solubility in CO₂ compared to the precursors of polyether. For example, the cloud point pressure decreased from 24.6 MPa for poly(1,2-propene glycol) (PPG) to 16.5 MPa for poly(dimethylsiloxane-alt-propene glycol) (PSPG) with a concentration of 0.6 wt% at 30 °C. Moreover, the molecular weight dependence of solubility for PSPG and PSDPG in CO₂ compared with PPG was weakened. The key factor to enhance the solubility of poly(silyl ether)s in CO₂ was systematically researched via surface tension and glass transition temperature. The results demonstrated that higher solubility of synthesized poly(silyl ether)s in CO₂ compared to PPG was mainly attributed to lower polymer–polymer interactions.