Polystyrene phenyl ring substituents

Substituents on the phenyl ring in polystyrene (PS) also increase the Tr Two substituents may have a greater effect on the Tg than one. The Tg values of o-methyl and p-chlorophenyl pendant groups in polystyrene are 388 and 401 K, respectively. 

A pictorial summary of the positions where substituents can be placed on the phenyl ring of polystyrene is given in Figure 28.2. 

Excimer Stability While the adjacent phenyl rings in polystyrene form relatively stable excimers, putting substituent groups on the phenyls may alter the bonding energy. Chakraborty et al. (44) substituted bulky t-butyl groups in the para position. 

The butyrate substituents are larger than those for other polymers listed, but they are not proportionately larger than the exceptional length of the structural unit of cellulose. An inspection of models shows that the three butyrate units can be accommodated about the cellulose ring with less obstruction than for the phenyl groups of polystyrene, for example. 

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