ISSN:
0360-6376
Keywords:
Physics
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The rate and molecular weight profiles were obtained for the spontaneous alternating copolymerizations conducted with diethylaluminum chloride. The rate formally fitted an expression, R = kp[MMA][Sty], and the rate constant was established by two distinct methods: (1) from the yield versus time data and (2) from initial rate over a range of initial concentrations; it was determined as 5.4 × 10-6 l./mole-sec with Ea = 4.2 kcal/mole. Molecular weights were determined by gel-permeation chromatography. No increase in molecular weight was observed with increased reaction time. Thus living centers or diradicals are not involved in the process. The M̄n shows a steady decrease with increase in monomer-diethylaluminum chloride concentration but the rate is maximum at equimolar monomer concentrations. The data are interpreted on a chain-transfer mechanism and show close agreement to a model in which the excess complexed acceptor monomer is the transfer agent. The chain-transfer constant of 7.1 × 10-4 l./mole-sec is several orders of magnitude greater than for uncomplexed systems.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1976.170141105
