Development of UV LED Hydrogel Formulation Based on Polyacrylamide Hydrogel

Abstract

Recent trends show that the UV LED light source can greatly reduce environmental effect without compromising performance as compared to conventional UV mercury-based lamp (UV Hg) system. In this study, the possibility of using UV LED technology for photopolymerization of polyacrylamide (PAAm) hydrogels is presented. This has strongly drives the needs for suitable water-soluble photoinitiator formulation. Specifically, the photoinitiator must possess characteristic wavelength within UV LED range as UV LED emits monochromatic light sources only (365 nm or 385 nm). Here, the commercially available photoinitiator Oligo [2-hydroxy-2-methyl-1-[4-(1-methylvinyl) phenyl] propanone] (Chivacure 300) was chosen. However, Chivacure 300 has limited solubility in water. Hence, addition of tetrahydrofuran (THF) at various ratios was required. The results demonstrated that 9.5:0.5 ratio of water/THF was the minimum ratio needed for the solubility of Chivacure 300. After the synthesis of PAAm hydrogels, almost complete conversion of hydrogels was achieved (> 80 %). The highest conversion was achieved with formulation of Chivacure 300 in 9.5:0.5 ratio of water/THF. At this ratio, the hydrogels obtained were transparent. With increasing ratio of THF in water, the appearance of hydrogels gradually changed to cloudy. Indeed, UV LED technology can be used to polymerize PAAm hydrogels with comparably high conversion to conventional UV Hg system.

Binary phase solid‐state photopolymerization behavior of acrylate cryogels under different light sources

“…Since these gels can swell in volume through intake of liquid into their structures when subjected to water or any drug or emulsion, they are considered potential candidates for a variety of biomedical applications, such as tissue engineering, bone regeneration and restoration, drug carriers, and actuators in the body . Chemical crosslinking using monomers is the only well‐recognized method of synthesizing these polymer gels, and one of the conventional but critical crosslinking techniques is photopolymerization . This solid‐state photopolymerization can be used for the synthesis of crosslinked polymer gels using monomers via photoinitiators in the presence of ultraviolet (UV) light …”