Evaluation of alternative models for the mechanism of chain‐growth copolymerization

Abstract

A general method for discriminating between different models for chain‐growth copolymerization is described. The method is based on the non‐linear least‐squares analysis of variations in the copolymer compositions or sequence distributions with the compositions of the monomer feed mixture. It allows the best values for the reactivity ratios for each model to be evaluated, and their joint confidence regions to be delineated. The method is demonstrated by applications to the copolymerizations of styrene with acrylonitrile and maleic anhydride.

Sequence Distribution and Stereoregularity in Styrene/Butyl Methacrylate Copolymers Obtained at High Conversion by Stable Free-Radical Polymerization

“…Although, for most copolymer systems, the copolymer composition has been shown to be fit by the terminal model, [2,3] comonomer sequence distribution is a much more sensitive probe of copolymer microstructure and, hence, of copolymerization mechanism. [4,5] In recent years, "living"/controlled free-radical polymerization has attracted considerable interest due to the advantages of free-radical procedures (reaction conditions not especially harsh) and living procedures (control over molecular weight, chain ends and macromolecular architecture). Several methods have been developed that enable "living"/controlled radical polymerization, including stable free-radical polymerization (SFRP), atomtransfer radical polymerization (ATRP) and reversible addition/fragmentation chain transfer (RAFT).…”

“…However, as has been previously stated, sequence distribution can discriminate between copolymerization models much better than composition. [4,5] Hence, this work analyzes the sequence distribution and stereoregularity of copolymers prepared by SFRP by means of 13 C NMR spectroscopy, not only to test the Mayo-Lewis terminal model, but also to determine if the copolymer microstructure and its variation with conversion in living/controlled free radical polymerization can be described by the same parameters as in conventional radical polymerization.…”

Understanding and controlling the structure of thin polymer films used in photolithography

“…A computer program REACT, developed by Hill and co-workers [281][282][283], has been used to predict the instantaneous copolymer compositions and triad distributions for all four monomer feed ratios using the terminal model. The data were predicted until 90% conversion with step size 0.01%.…”