Photochemically Induced Cationic Photopolymerization of Vinyl Ethers and Oxetanes

Abstract

Abstract. 2,3-dihydrofuran can be polymerized by means of cationic photoinitiators yielding 100 % polymer in less than 120 seconds at room temperature. The product is colorless, has good film forming properties and does not show any side reaction such as aldehyde formation. Several mono-, bi-and trifunctional oxetanes were synthesized in bulk and in solution cationically. Selected photoinitiators have been applied. It was found that sulfonium salts are very efficient due to good solubility, almost no discoloration of the product and storage stability in the monomer in the absence of light. The conversion was determined by quantitative IR-spectroscopy. Conversion between 75 % and 85 % was found in all cases. The shrinkage during polymerization was much lower than for vinyl monomers. No inhibition by oxygen was observed. Monomer layers thicker than 5.5 mm could be polymerized. The products are transparent and almost colorless. The glass transition temperature of the crosslinked polymers was above 37°C (temperature of the human body).

The quantum-chemical modelling of structure and spectral characteristics for molecular complexes in pentaplast-terlon system

“…Side reactions such as ring formation and backbiting can be reduced by lowering the reaction temperature. These reactions can be more or less ignored in the case of composites, if bi-and higher functional monomers are applied [3]. Recently, the importance of the research of numerous polymer systems, based on pentaplast, reinforced with different fiber materials, such as poly-p-phenyleneterephtalamide (terlon) has grown [4].…”

Free Radical Copolymerisation ofN-Methylmaleimide and 2,3-Dihydrofuran Initiated by their Radical Cations. A Low Temperature EPR Study of a Binary System

“…mer classes, as they not only copolymerise rapidly, but are also more stable towards hydrolysis compared to the simple vinyl ethers. [22,23] In addition, 2,3-dihydrofuran, like vinyl ethers in general, does not homopolymerise by a free-radical mechanism. [24] Cationic polymerisation of this monomer is possible, but improbable in freon matrix and accordingly was not found by Knolle et al [25] The chemistry of 2,3-dihydrofuran-derived radical cations and radicals in freon matrix has furthermore been extensively investigated.…”