Advancing spin-coating technique for semi-crystalline low-density polyethylene thin films

Abstract

Polymeric thin films are widely used for coating substrates or as freestanding materials. They are prepared using physical/chemical vapor deposition, dip coating, solution casting, or spin coating. Among these, spin-coated films offer uniform thickness and reproducible results. These films are typically made from amorphous polymers, which are soluble in solvents at ambient temperature, making it easier to coat the polymer solution on the substrate. Despite the advantages of this technique, it has hardly been used for semi-crystalline polymers. In this work, we report the synthesis of freestanding porous thin films using semi-crystalline polymers, specifically low-density polyethylene (LDPE), through the utilization of spin coating. The effect of polymer concentration and porosity on thickness and strength was investigated. The as-prepared thin film was characterized by XRD, XPS, FTIR, and SEM techniques. The increase in crystallinity (14 % change) of the thin film was attributed to the rearrangement and uniform alignment of the polymer chains, which further resulted in relatively higher tensile strength.