Degradation of ultra-high molecular weight poly(methyl methacrylate-co-butyl acrylate-co-acrylic acid) under ultra violet irradiation

Abstract

A new acrylic terpolymer, poly(methyl methacrylate-co-butyl acrylate-co-acrylic acid) [P(MMA-co-BA-co-AA)] of ultra-high molecular weight (UHMW) was synthesized via seeded emulsion polymerization. This polyacrylic showed good film properties; high transparency, water resistance and mechanical flexibility that may suitable for many environmental based applications such as coating, packaging, label sensors etc. In order to access the photo-stability of this material for environmental application, studies were conducted under UV illumination of a short-wavelength (l ¼ 254 nm) in air. The responses were collected at different irradiation times by using several characterization techniques: infrared/UV-visible spectroscopy (FTIR/UV-Vis), gel permeation chromatography (GPC), atomic force microscopy (AFM) and thermogravimetric analysis (TGA). Two distinguishable structures, cross-linked and fragmented chains, were formed under photo-irradiation at different times of exposure. The formation of cross-linked structures at short irradiation times (t < 60 min) increases the chain length as validated from the increase in average-molecular weight (M w ), whilst at longer irradiation time the fragmentation causes a decrease in the chain length (decrease in M w ). Only the chain scission at longer irradiation time (t > 60 min) causes the copolymer to degrade. The centre of reaction was identified at the pendent group and no effect of main chain destabilization was observed throughout the experimental condition. The occurrence of chain cleavage during photo-degradation causes chain-chain separation, as visually seen under the imaging technique and this coincides with the observed drop in thermal stability. Photo-oxidation was also proposed to occur simultaneously with photo-degradation as the irradiation was performed in air.

Waterborne Acrylate-Based Hybrid Coatings with Enhanced Resistance Properties on Stone Surfaces

“…Furthermore, minor changes in band intensities were observed, evidencing chemical changes in the copolymer upon UV irradiation. The band underwent prominent changes is the carbonyl (C=O) stretching, which variation, as previously reported [52], was quantified after UV exposure. Indeed, considering the decrease of this band, the relative amount of the remaining functional group was determined by the ratio of IR absorbance at 1726 cm −1 after aging and the absorbance of the unexposed sample (Figure 4a) [55].…”

“…Figure 3a shows the FTIR spectra of nonirradiated copolymer without and with 10 wbm% of silica. The spectrum of the neat polymer (Figure 3a [52]. After the addition of the inorganic components (Figure 3a, black curve), strong absorption bands appear at 1118 and 476 cm −1 due to Si-O-Si stretching and bending, respectively, and at 1068 cm −1 related to Si-O bending.…”

Inherent Photodegradability of Polymethacrylate Hydrogels: Straightforward Access to Biocompatible Soft Microstructures

“…Most studies were conducted to gain insight about the lifetime of homopolymer's upon exposure to sunlight or their usefulness as photoresist . Two major processes caused by UV irradiation were identified: photoinduced degradation and crosslinking, with the amount crosslinking being quantified simply by determining the mass of the insoluble fraction forming from a former soluble homopolymer . It was found that polyacrylates tend to crosslink more than the respective polymethacrylates and that longer aliphatic ester side chains resulted in more photo‐crosslinking.…”

Photo-oxidation stability of microcapsules in thermochromic prints

“…Acrylated resins are used predominantly in oligomer systems and their combinations include epoxy, polyester and urethane prepolymers. They all contain a carbonyl group (Thompson, 2004;Du, et al, 2017;Shanti, et al, 2017).…”