Synthesis of segmented polyurethanes containing different oligo segments: Experimental and computational approach

Abstract

Incorporation of hydrophilic and hydrophobic agents into a polymer backbone is an effective approach to control its interfacial characteristics. Segmented polyurethanes (PUs) are easy-fabricating and cost-effective candidates in this respect. In this work, we have synthesized polycarbonate (PC)-based PUs containing hydrophilic Polyethylene glycol (PEG) and hydrophobic Polyhedral Oligomeric Silsesquioxane (POSS) in the lab as well as in molecular dynamics simulations. We employed several experimental techniques and a coarse-grained (CG) molecular dynamics (MD) method to evaluate the morphology and microphase arrangement of PUs. We successfully synthesized superior hydrophilic and hydrophobic coatings by replacing some parts of the soft segment (PC) with PEG and the chain extender (1,4-butandiol) with POSS, respectively. Our CG MD simulations showed that POSS is dispersed in PC uniformly, while PEG is completely phase separated from PC and formed a lamellar structure. This was also confirmed by experimental thermal analysis. Eventually, water contact angle (WCA) measurements proved development of very hydrophilic (PU-PEG), slightly hydrophilic (PU), and very hydrophobic (PU-POSS) coatings. The surface free energy analysis indicated that POSS decreases polar and apolar components of surface free energy, while PU-PEG exhibits omniphilic behavior. The presence of PEG and POSS on the surface was also confirmed by contact angle and AFM measurements. According to MTT and LDH assays, PEG and POSS incorporation significantly enhanced the biocompatibility of PU such that PU-PEG and PU-POSS coatings become prospective candidates for biomedical applications.