Enhancing polymethyl methacrylate (PMMA) surfaces: Taguchi optimization of PPy coating synthesis and surface modification strategies

Abstract

Polymethyl methacrylate (PMMA) is commonly used in many industries because of its lightweight and optical clarity. However, its weak adhesion properties and low electrical conductivity limit its use in advanced electronic and functional devices. This study introduces a new method to overcome these issues by using both mechanical sanding and chemical etching, combined with the deposition of polypyrrole (PPy) coatings on PMMA surface (PPy/PMMA). This method is being applied to PMMA substrates for the first time, making this work distinct from previous studies. Sanding enhances surface roughness of PMMA surface by creating micro-scale features that improve adhesion, as shown by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Meanwhile, chemical etching with piranha solution (H₂O₂/H₂SO₄) introduces functional groups on PMMA surface, which improve wettability and bonding with PPy. This enhancement is confirmed by X-ray photoelectron spectroscopy (XPS), contact angle measurements, and adhesion tests. On the other hand, this study optimized the synthesis of PPy using Taguchi design, showing the pyrrole concentration as a critical factor for achieving high PPy yield. Additionally, various methods were explored to increase the electrical conductivity of PPy/PMMA coatings. Dodecyl sulfate as doping anions (DS/PPy/PMMA) and silver particles incorporated into the PPy backbone (Ag/PPy/PMMA) were synthesized by electrochemical and chemical techniques, respectively. These changes resulted in notable improvements in both conductivity and Raman scattering characteristics of the PPy coatings. This efficient and scalable approach addresses important challenges in PMMA surface modification, increasing its suitability for advanced electronic and functional applications.