Photopolymerization of Hexamethylene Bisacrylate

Safetyprecautions Before this experiment is carried out,Sect.2.2.5 must be read as well as the material safety data sheets (MSDS) for all chemicals and products used. 

In a 50-ml round-bottomed flask 5 g hexamethylene bisacrylate and 0.2 g of 2-hy-droxy-2-methyl-1 -phenylpropane-1-one as a photoinitiator are stirred until a homogeneous solution is obtained.The flask is evacuated for a short time to remove bubbles from the solution. An IR spectrum is taken of the homogeneous solution. 

Part of this solution is now spread on a glass plate with a spatula and irradiated with UV light (Hg medium-pressure lamp), until a hard crosslinked and insoluble film is obtained (5 min).The distance between the source of radiation and the substrate should be about 20 cm.This Is an example of a photo-cured coating. 

In a second experiment a mask,e.g., a coin, is placed between the substrate and the source of radiation by means of a holder. After 5 min the unexposed part of the film is removed by treating with an organic solvent.This is an example of surface structuring by photolithography. 

The irradiated film shows an absorption band in IR spectrum (KBr pellet) at 1635 cm T The increase in intensity of this absorption with time is a measure of the conversion rate. Parallel to this the solubility/swelling of the film in THF or toluene should be qualitatively determined. 

Part of this solution is now spread on a glass plate with a spatula and irradiated with UV light (Hg medium-pressure lamp), until a hard crosslinked and insoluble 

---