4-Perchloratobutyl Acrylate, a New Monomer for Self-Crosslinking Thermosetting Acrylic Resins

4-Perchlorato butyl acrylate (pCBA) is prepared in a one-pot reaction and copolymerized with methyl, ethyl resp. butyl acrylate to give a polyacrylate binders with upto 11 mol% pCBA. Thermally curing in the range of 105 degrees C-135 degrees C gives a thermoset by a transesterification, eliminating alkyl perchlorates. The resulting 1,4-linker motive and the volatile alkyl perchlorates were identified spectroscopically (IR, TGA, (CP MAS) NMR) and validated by direct synthesis of the resin. The crosslinking process was monitored by FT IR spectroscopy (complete within an hour at 135 degrees C) and by TGA (onset temperature of 145 degrees C, 154 degrees C resp. 171 degrees C for methyl, ethyl and butyl acrylate copolymer with about 11 mol% pCBA). The crosslink density (0.15-2 mol/L) and glass transition temperatures (-12 degrees C to 20 for copolymer of ethyl acrylate with 0.9-8 mol% of pCBA) increase proportionally to the pCBA content. Tetrahydrofuran is detected as further cleavage product, resulting from a competitive pathway leading to carboxylic acid moieties and probably crosslinks (of unknown structure).