Presenters Name: Dr Phil Barker

Employment Title: Associate Professor

Company: University of Wollongong, School of Chemistry and Molecular Bioscience.

Biography: Phil was educated in the UK. During a spell working in Germany, he was recruited by the former BHP Research in 1988. Initially based in Melbourne, Phil transferred to Port Kembla in 1995 to work on various R & D projects related to the iconic COLORBOND®steel product range. Over the years he became known globally as an expert in coating durability and testing. After more than 26 years with BHP Research (latterly BlueScope Steel Research), Phil was retired in late 2014 and he moved across to the University of Wollongong, where he works on various coating-related research projects.

Presentation Title: A new method for evaluating photoinitiator efficiency: application to LED395 curing and a molecular understanding of oxygen inhibition.

Presentation Abstract: The transition from traditional mercury lamp UV curing to LED is inevitable but also challenging in many ways. Traditional UV formulations rarely translate seamlessly to LED for several reasons, one of them being that there are fewer photoinitiators suitable for LED, whichever wavelength LED array is chosen. Review of a catalogue recently showed that one manufacturer offered 46 photoinitiator products for traditional UV cure, but only 13 products for LED. In this project a series of novel monoacylphosphine oxide (MAPO) photoinitiators has been synthesised with various substitutions on both the acyl and phosphine oxide moieties. These substitutions have been carefully chosen to attempt to increase the reactivity of free radicals produced when the MAPO molecule is cleaved by LED395. The reactivities of 9 new photoinitiators have been benchmarked against an industry standard photoinitiator, Lucirin® TPO, using a new technique developed in our laboratory and published recently [1]. Here, a photoreactor cell is interfaced to a mass spectrometer, which allows polymerisation to be followed in ‘real time’. In this talk, I will describe the experimental set-up and present results from the 9 new photoinitiators. The key advantage of the method is that the photoinitiator efficiency can be determined rapidly, using only a few milligrams of sample. This means that labour intensive formulation ladders and time-consuming laboratory experimentation may be unnecessary.