The network structure of syndiotactic-polystyrene (sPS)- or syndiotactic-poly(styrene-co-4-R-styrene)-organic solvent gels has been quantitatively studied by means of scanning microscopic light scattering (SMILS). SMILS analysis indicated that sPS gels prepared in chloroform, benzene, toluene, and o-dichlorobenzene (ODCB) formed network structures with small mesh sizes, ∼0.6-1.8 nm, and large cluster structures, ∼1000-6000 nm. The cluster size in the gels increased with increasing sPS concentration. The mesh and cluster sizes of sPS gels prepared in ODCB was the smallest among the used solvents owing to its high viscosity. Gelation of the St/CH 3 St (MeSt)-toluene system at high temperatures induced slow gel formation and made it possible to trace the time evolution of the network structure by SMILS. tert-C 4 H 9 St (BuSt) units in St/BuSt drastically decreased the gel formation rate, and the formation process of the St/BuSt-toluene system could be traced by SMILS and FT-IR spectroscopy at room temperature. The results indicated growth of the cluster structure during gelation. St/4-hydroxystyrene formed gels in dioxane. A gel of an St copolymer containing an anthracene (An) group was prepared in toluene, and photodimerization of the An groups was induced by UV irradiation accompanied by formation of the large cluster structure.
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