Publications [#62117] of Kam W. Leong

Papers Published

1. Richards, M. and Dahiyat, B.I. and Arm, D.M. and Lin, S. and Leong, K.W., Interfacial polycondensation and characterization of polyphosphates and polyphosphonates, Journal of Polymer Science, Part A: Polymer Chemistry, vol. 29 no. 8 (1991), pp. 1157 - 1165 [pola.1991.080290809]
   (last updated on 2007/04/13)

   Abstract:
   The synthesis of four bisphenol A-based polyphosphates and phosphonates was accomplished. The polymerization involved a condensation between bisphenol A and a phosphorodichloridate. The heterophasic polycondensation technique was used with the aid of a phase transfer catalyst to yield molecular weights in the range of 20,000-40,000. The polymers were characterized by FT-IR, FT-NMR, and DSC. Systematic studies on the interfacial polymerization indicated that a more concentrated organic phase and a slight excess of diol favored the production of high molecular weight polymers. An optimum concentration of 5-10 mol % was observed for three different phase transfer catalysts. Kinetic studies showed that the polymerization was complete within the first 10 min. The degree of agitation was shown to be important, as the overhead mechanical stirrer was not as effective as the blender. In addition, crosslinking with pentaerythritol yielded significant increases in the molecular weights of these polymers.

   Keywords:
   Polymerization - Condensation Reactions;Chemical Reactions - Reaction Kinetics;