DIRECT KINETIC MEASUREMENTS OF VINYL POLYMERIZATION ON METAL AND SILICON SURFACES USING REAL-TIME FT-IR SPECTROSCOPY

A real-time FT-IR (RT/FT-IR) technique has been used to perform direct kinetic measurements of vinyl polymerization on metal and silicon sur faces. Here, we are reporting our results in studies of anaerobic and photo-induced anionic polymerizations of monomers containing vinyl fun ctional groups (>C=C<) for adhesive and coating applications. For anae robic polymerization we are investigating the hydroperoxide-initiated free radical polymerization of model multifunctional methacrylate mono mer systems. We will report the results of our studies on the catalyti c effects of different dithiolate complexes and related accelerators. In photo-induced anionic polymerization we will report our studies for ethyl cyanoacrylate (CA) polymerization initiated by a controlled rel ease of anion from a stable chromium complex precursor (trans-Cr-(NH3) 2(NCS)4-K+) Because of high surface sensitivity of the CA monomer, the polymerization kinetic studies were performed on a clean silicon surf ace at room temperature. The effect of the initiator concentration and irradiation wavelengths on polymerization kinetic rate will be discus sed. The acrylic polymerization was monitored with the use of the C=C stretching band at 1634 and 1627 cm-1 for polyglycol dimethacrylate an d cyanoacrylate, respectively. Both the degree of polymerization and t he intrinsic rates of the polymerization reactions were calculated for kinetic comparisons. For anaerobic polymerization studies, GC/FT-IR s oftware was used which provided a real-time screen display of IR spect ral changes as the reaction proceeded. For very fast cyanoacrylate ani onic polymerization studies, new FT-IR kinetic software was used to co llect 204 spectra per minute with one spectrum per scan. In this case, the interferograms were collected first; post-Fourier transform conve rsion and spectral script reduction were then performed. Some detailed experimental techniques and polymerization reaction mechanisms will a lso be discussed.