Photochromism in main-chain polymers

A similar synthetic approach was used to prepare polymers 40 [68, 81] and 41 [82, 83]. The presence of silyl groups in 41 is important as they increase the solubility of the polymer in organic solvents and promote the formation of a transparent and homogeneous film when spin cast from solution. An interesting application for polymer 41 is its use as a template for micropatterning using a two-step procedure [84]. A film of polymer 41 is selectively irradiated through a contact mask to provide a conductive pattern. 

An alternative approach to develop cross-linked photoresponsive polymers for use as photochromic coatings (47) relies on the quatemization of the amine groups of IV-methyldiethanolamine polyterephthalate by a mixture of bis(2,5-dimethyl-4-chloromethyl-3-thienyl)-l,3-dioxol-2-one and p- or m-xylylene dichloride in different ratios [92]. The coatings obtained using this method exhibit photochromic behavior, although some examples of the ring-closed forms did bleach back to the ring-open isomers when stored in the dark. 

If ROMP of a strained norbornene produces a cyclopentane (see polymers 35-37, for example) then the analogous reaction of a norbornadiene will produce a cyclopentene. Using this logic, photochromic main-chain polymers (48) have been prepared and studied (Chart 21.9). These polymers all contain a 

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Handbook of Thiophene-based Materials Applications in Organic Electronics and Photonics 21.4.3 Photochromism in main-chain polymers... 

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