Molecular weight determination early results

During the early years of this century, organic chemists were enjoying success in determining the structures of ordinary-sized organic molecules, and this probably contributed to their reluctance to look beyond structures of convenient size. Physical chemists were interested in intermolecular forces at this period, and the idea that polymers were the result of some sort of association between low molecular weight constituent molecules prevailed fora long while. 

These results were confirmed by Sung and Han (1995). They observed that addition of a PS-PB diblock copolymer to a blend of the corresponding homopolymers (of lower molecular weight than the diblock) leads to a retardation of phase separation in both early and late stages. Using time-resolved light scattering they determined the spinodal peak position and intensity as a function of time. Addition of copolymer was found to reduce the critical temperature of the blend. 

The molecular weight was indicated by rough determinations of the density by the early workers, - these results were, however, in all eases too low on account of admixture with hydrogen ( . supra). 

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