Surface Wetting Behaviors of Hydroxyl-Terminated Polybutadiene: Molecular Mechanism and Modulation.

Abstract

The surface wetting or coating of materials by polymers is crucial for designing functional interfaces and various industrial applications. However, the underlying mechanisms remain elusive. In this study, the wetting behavior of hydroxyl-terminated polybutadiene (HTPB) on a quartz surface was systematically investigated using computer simulation methods. A notable tip-dominant surface adsorption mode of HTPB was identified, where the hydroxyl group at the end of the polymer chain binds to the surface to initiate the wetting process. Moreover, it was found that with the increase in the degree of polymerization (e.g., from DP = 10 to 30), spontaneous adsorption of HTPB becomes increasingly difficult, with a three-fold increase in the adsorption time. These results suggest a competition mechanism between enthalpy (e.g., adhesion between the polymer and the surface) and entropy (e.g., conformational changes in polymer chains) that underlies the wetting behavior of HTPB. Based on this mechanism, two strategies were employed: altering the degree of polymerization of HTPB and/or regulating the amount of interfacial water molecules (e.g., above or below the threshold amount of 350 on a 10 × 10 nm² surface). These strategies effectively modulate HTPB's surface wetting process. This study provides valuable insights into the mechanisms underlying the surface adsorption behavior of HTPB and offers guidance for manipulating polymer wetting processes at interfaces.