Enhanced Photostability of PMMA via Functionalization With Aromatic Aldehyde Hydrazone Derivatives

Abstract

Poly(methyl methacrylate) (PMMA) is an extensively utilized thermoplastic polymer in different fields, including automotive, construction, electronics, medical devices, and optical applications. The polymer possesses excellent optical clarity, weather resistance, and mechanical properties, which make it an attractive alternative to glass in many applications. However, one of the main drawbacks that limit the wider application of the polymer is its susceptibility to UV light. This radiation can initiate free radical reactions that compromise the structural integrity of the polymer and deteriorate its mechanical properties. The addition of photostabilizers can reduce the rate of photodegradation in the polymer significantly. In this study, PMMA was first modified with hydrazine and then separately functionalized with four different aromatic aldehydes, namely 2-nitrobenzaldehyde, 4-nitrobenzaldehyde, 3,4-dimethoxybenzaldehyde, and 4-bromobenzaldehyde. The modified polymer films were characterized using Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (1H NMR), and energy-dispersive X-ray (EDX) mapping. In addition, the photo-protection provided by these photostabilizers was examined in terms of functional group indices, weight loss percentage, scanning electron microscope (SEM), and atomic force microscopy (AFM). All modified polymers demonstrate remarkable photostability after 300 h of irradiation (365 nm) compared to the unmodified polymer, which exhibits significant weight loss and surface damage. Therefore, this study provides a simple and efficient method to address the photodegradation issue of PMMA.