Polyurethane covalently modified polydimethylsiloxane (PDMS) coating with increased surface energy and re-coatability

Abstract

In the present study, with 2-Allyloxyethanol-terminated polyurethane (AEPU) and allyloxy (polyethylenene oxide) methyl ether-graft-polymethylhydrosiloxane (PMHS-g-AEM) as modifier and reactive compatibilizer respectively, a type of polyurethane modified polydimethylsiloxane (PUMS) coating with increased surface energy and re-coatability was obtained via solvent-free two-component hydrosilylation reaction. The structures of as-prepared AEPU and PMHS-g-AEM were characterized by FTIR and 1H NMR, and the AEPU distribution in PUMS together with the characteristics of resultant coatings, such as dynamic wetting properties, surface roughness, surface energy and re-coatability, variation in curing behavior and mechanical properties were also elaborately evaluated. From scanning electron microscope (SEM) observation, it is found that in presence of 2 wt% compatibilizer, AEPU can be distributed in PUMS uniformly. With the increase of AEPU loading, the coating surfaces show a decreased water contact angles (WCAs), increased surface roughness and enhanced surface tension from 29.4–52 mN/m as well as re-coatable feasibility. Intriguingly, curing kinetics study reveals that the conjugation of 10 wt% AEPU into two-component hydrosilylation system can significantly reduce the reaction activation energy by 43.6 %. Another interesting result is that the chemical incorporation of AEPU dramatically improves elongation at break of PUMS film from 460 to 808 % while well-maintains tensile strength. All aforementioned results distinctly demonstrate a feasible yet promising paradigm for modifying PDMS coating with polyurethane.