INDEX 16 aneS

Kudo H, Yamamoto M, Nishikiibo T, Moriya O. 2006. Novel materials for large change in refractive index synthesis and photochemical reaction of the ladderlike poly(silsesquiox ane) containing norbomadiene, azobenzene, and anthracene groups in the side chains. Macromolecule 39 1759 1765. 

Each of the two quantitative spectra of poly(ethylene glycol) (PEG) depicted in Fig. 41 exhibits an end-group (OH) resonance at 3.2 ppm and a main -O-CH2 CH2O- peak at 3.9 ppm. The molecular weights of these two products can easily be calculated by NMR, based on the relative intensity ratio of the end to main peaks. Rare spins ( C and Si) can also be used to determine molecular weight, as demonstrated for several polysilox-anes [117]. A commercially available on-line system tracks both density and melt index (which is related to molecular weight) based on wide-line H experiments [118]. GPC/NMR, a variant of LC/NMR, has been used to track the molecular-weight distribution of poly(methyl methacrylate) [119]. 

The refractive index of Si02-Ti02 hybrid films can be tailored by changing the amount of Ti in the material or by using acetylacetone [281] and oligosilox-ane-titania hybrid resins [282] via nonhydrolytic process. 

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