Poly stabilization, recent fundamental

Recent Fundamental Developments in the Chemistry of Poly(vinyl chloride) Degradation and Stabilization... 

Several fundamental studies have shown the importance of monomer sequence distribution on mesophase behavior (26). Simply changing the direction of ester linkages in a chain affects the transition temperatures, the range of the mesophase stability and, in some cases, even the mesophase texture (2Z). Polyester chains are susceptible to transesterification, which raises the question of which sequence structure is actually responsible for the properties observed for a given polymer. A recent study of aromatic LC polymers by neutron scattering indicates that transesterification occurs in the mesophase at rates twice that in poly(ethylene terephthalate) (28). Such behavior has also been observed to occur in other aromatic polyesters where rapid sequence redistribution was detected by nmr, see for example, the chapters by Jin and Economy et al. The temperature dependence of this effect has not been fully explored, and it may not be as pronounced in those polymers which exhibit mesophase behavior at lower temperatures, for example, those with aliphatic spacers. 

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