Chain‐end lactonization of polyacrylates prepared by photopolymerization

Abstract

ABSTRACT:The structural change of the end groups of UVcured acrylates with time has been investigated as well as photopolymerization behavior. 2-Ethylhexyl acrylate, n-lauryl acrylate, 2-(2-ethoxyethoxy)ethyl acrylate, and 2-ethylhexyl methacrylate were used as a monomer in the current study. In order to mimic industrial conditions, the photopolymerization was conducted with relatively high UV intensity (576 mW/cm 2 ) using a common photoinitiator 1-hydroxycyclohexyl phenyl ketone. Conversion-time profile gave a linear first-order plot suggesting that the steady state was hold throughout the polymerization. Matrix-assisted laser desorption/ionization time-offlight mass spectra of the resultant polymers indicated the number of the hydroxycyclohexyl chain-ends decreased with storage time at room temperature. Instead, a lactonic ring appeared to form at the chain-end by transesterification of the hydroxycyclohexyl group with the ester side chain of the adjacent acrylate according to the results of mass spectrometry and 13 C NMR.

Cross‐linking photopolymerization of monoacrylate initiated by benzophenone

“…At higher conversion, the resultant polymer could not be dissolved in solvents due to gelation (i.e., highly cross-linked polymer formed during UV irradiation), while gelation was not observed for the photopolymerization of n-LA using 1hydroxycyclohexyl phenyl ketone as an initiator as we previously reported. 19 The conversion at which the gel started to form is defined as "gel point." The percentage of the gel separated from the soluble fractions is plotted against time in Figure 2(a,b).…”

Preparation and characterization of pH-sensitive hydrogels from photo-crosslinked poly(ethylene glycol) diacrylate incorporating titanium dioxide

“…A photopolymerization-curing technique provides an easy preparation of the films based on the PEG-based materials Also, photopolymerization is efficient, energy saving, and environmentally friendly technology due to easily controlled process parameters and a rapid curing rate. This method is widely used for coatings, dental restorative materials, lenticular lenses, and photolithography [21][22][23][24][25].…”