Branching by reactive end groups. III. Synthesis, branching, and analysis ofm-ethynylphenol/p-t-butylphenol-coterminated bisphenol a polycarbonates

Autor: Maurice J. Marks, J. Newton, S. E. Bales
Rok vydání: 2000
Předmět:
Zdroj: Journal of Polymer Science Part A: Polymer Chemistry. 38:2352-2358
ISSN: 1099-0518
0887-624X
Popis: The use of m-ethynylphenol (m-EP) and p-t-butylphenol (PTBP) as coterminators for bisphenol A polycarbonates (BA PCs) provided long-chain-branched PCs, partially crosslinked PCs, or both after the thermal reaction of the terminal m-EP groups, depending on the molar ratio of the chain terminators. Linear m-EP/PTBP PCs were prepared by solution phosgenation of BA and the two coterminators. Differential scanning calorimetry showed the onset of the m-EP-end-group reaction at about 250 °C by the appearance of a reaction exotherm. The enthalpy (ΔH) of this reaction was roughly proportional to the amount of m-EP in the PC and to an extent could be used to monitor the progress of the reaction and estimate its kinetics. A complete m-EP-end-group reaction was evident from gel permeation chromatography analysis upon heating under N2 to 380 °C for 10 min or 360 °C for 60 min. The amount, if any, of gel formed after the m-EP-end-group reaction depended on XEP; those PCs with a XEP value less than or equal to 0.33 had little or no gel. The maximum XEP that precluded the formation of gels after branching was estimated to be about 0.45–0.48. The molecular weight of m-EP/PTBP PCs increased after branching, as evidenced by gel permeation chromatography analysis. Assuming that the terminal m-EP groups had a statistical distribution on the polymer chain ends and that they underwent only homopolymerization, the average reacted m-EP-group functionality according to estimated gel-point composition was about 2.8–3.0. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2352–2358, 2000
Databáze: OpenAIRE
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