Photosensitive materials, polysilanes

Quantum Yields of Photolysis. These photochemical studies on high-molecular-weight polysilanes suggest that these polymers constitute a new class of photosensitive materials. The bleaching studies indicate that significant molecular weight reduction occurs upon irradiation in air or in vacuo, which in turn implies that the polymers are predominantly of the scissioning type. 

A number of reviews have appeared of topical interest. These include photoisomerism of azo dyes, ° photofunctional polysilanes,photochromic pigments, rare earth complexes, pressure sensitive paints, electron-transfer processes,electroactive dendrimers, chiral polyisocyanates, photodefin-able benzocyclobutene, photoconductive polymers,excited states in conjugated polyenes, photosensitive materials and polyazomethanes. ... 

Microlithography, Xerography. Because of their photosensitivity, polysilanes are under intense investigation for use as positive photoresist materials (94) (see Lithographic resists). They are particularly attractive because both wet and dry development techniques can be used for imaging (131,132). The use of polysilanes for xeroprinting has been reported (133). Thermal and optical sensors based on the photodegradation of polysilanes have been developed (134). 

As explained in the introduction, the polysilanes (and related polygermanes and poly-stannanes) are different from all other high polymers, in that they exhibit sigma-electron delocalization. This phenomenon leads to special physical properties strong electronic absorption, conductivity, photoconductivity, photosensitivity, and so on, which are crucial for many of the technological applications of polysilanes. Other polymers, such as polyacetylene and polythiophene, display electron delocalization, but in these materials the delocalization involves pi-electrons. 

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