Synthesis and Application of Dual Functional Polymer Intermediates with Vinyl and Isocyanate Groups.

• Main Authors: Chien-Chang Chen, 陳建彰
• Other Authors: Shenghong A. Dai
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/73v6yr

博士 === 國立中興大學 === 化學工程學系所 === 98 === Two dual functional polymer intermediates with both vinyl and isocyanate functional groups have been successfully synthesized and studied as crosslinkers in this research. We demonstrated that the selective reaction and polymerization of either functionality, i.e. vinyl or isocyanate groups, can be exploited independently and sequentially in the formation of highly crosslinked polymers with high hardness and improved mechanical properties. In the synthesis of 4-vinylbenzyl isocyanate (4-VBI), the chlorine-atom of readily available 4-vinylbenzyl chloride (4-VBC) had to be replaced by iodine first through the action of potassium iodide (KI) in acetone solution to afford 4-vinylbenzyl iodide (4VBIodide) to enhance its reactivity. In the subsequent replacement step, 4-VBIodide was reacted with silver cyanate (AgCNO) in toluene solution to quickly afford 4-VBI in an overall yield of 85 %. Two polymerizations have been carried out to demonstrate the utility of 4-VBI. In the first experiment, a free-radical co-polymerization of 4-VBI with styrene was carried out and then was followed by the addition of 2-hydroxyethyl methacrylate (HEMA) to the obtained the random γ-PS-PVBI to consume the isocyanate in formation of urethane-acrylate functionalized graft-polymers. The acrylate groups in the graft-polymer could undergo UV-curing reaction to further strengthen its mechanical properties. In the second example, VBI was reacted first with trimethylolpropane (TMP) to form tri-functionalied vinylbenzyl urethane intermediates before carrying out the UV-curing reaction. It was surprised to see those vinyl group did crosslinked rapidly under UV-irridation to form polymers with their hardness from 8.7 sec. before the curing jumping to 174 sec. afterward. In the study of macrocyclic dual intermediates, our syntheses were based on addition of acrylic acid to the macrocylic carbodiimde (MC-CDI) in formation of acrylate-acylurea intermediates. Through this novel system, acrylate group were tested for its UV-curing ability, while the acylurea group was used as a latent isocyanate group that can release isocyanate upon heating. Again, we have studied two different reaction modes by either heating before UV-curing in the first case or by UV-curing before thermal treatment in the second case. Although the final results of those two processes will achieve about the same polymeric hardness of ~177 sec. in the final polymers, there are substantial differences in the physical natures of intermediates after the first stage treatment. For a better initial hardness and smooth surface, the dual curing processing appears to favor to start with the UV-irradiation. However, in achieving the final product’s thermal stability, the thermal curing in the initial step followed by the UV-irradiation has the advantages. Furthermore, in our co-polymerization study with MC-AU-A(T2P) and acrylate system, it revealed that at the content of only 27% for the MC-AU-A(T2P), the UV-curing formulation could achieve enhanced performances. In my final study, the dual intermediate concept has been applied to the functionalization of carbon nanotube (CNT) through addition of MC-CDI on to the carboxylic groups of CNT. This acylurea-functionalization of CNT was found to be a superior way of dispersing CNT in the organic media, so that the modified CNT stays in organic media for months without precipitation. Furthermore, the formed ringed acylurea groups attached to the modified CNT also can serve as latent reactive group capable to crosslinking polymers in formation of composites with chemically bonding to CNT. The modified CNT composite generally results in better mechanical properties than those with either pristine CNT or non-cured CNT composites. Through this research, we demonstrated the importance and significant capability of dual functional intermediates. With further structural and cost refinements, it is hoped that one of these products could be applied practically in the real world.