Effect of the copolymer composition on the K and α constants of the Mark-Houwink equation: Comments on a recent article by Songkhla and Wootthikanokkhan

Some serious problems in the experimental approach taken by Songkhla and Wootthikanokkhan which show that there is as yet insufficient evidence to undermine the validity of the weighted-average approximation for random styrene-methyl methacrylate copolymer in THF are highlighted. As such, the demonstration by Songkhla and Wootthikanokkhan of nonlinear aeffects on the Mark-Houwink constants of styrene-methyl methacrylate copolymers in THF does appear to contradict previous experiments. To resolve this contradiction, it is proposed that nonlinear effects observed by them are the result of the following problems in the experimental approach that are taken.