تسجيل الدخول

تسجيل

Polymers with Functional Chalcone Groups

المؤلف:  A. Ravve

المصدر:  Principles of Polymer Chemistry

الجزء والصفحة:  743-744

2026-03-07

363

Polymers with Functional Chalcone Groups

Pendant chalcone groups on polymers behave similarly to pendant cinnamate groups. Thus, photocross-linkable polymer can be formed, for instance, from poly (vinyl alcohol) by a reaction with 40-substituted-4-caboxychalcone in homogeneous dimethyl formamide solution, using 2,4,6 trinitro chlorobenzene as the condensing agent [155].

The photosensitivity of this polymer is in the range of 1–5 mJ/cm², according to Watanabe et al. [155]. When the R group shown above is p-Br, m-NO2, or (CH3)2N, the cross-linking is via formation of biradicals derived from the double bonds of the cinnamoyl groups and an abstraction of protons from the neighboring methyne or methylene groups. This reaction of dimerization can be illustrated as follows [156]:

Formation of polymers by reaction of free-radical polymerizable methacryloyl groups and a photocross-linkable pendant chalcone units was also reported [157]. The photocross-linking reaction takes place in thin films and in solutions upon irradiation with high pressure mercury lamps. The reaction can be monitored through changes in the UV absorption spectrum. The rates of photocross linking in solutions were reported to be faster than in films. Photocross-linking in the presence of a triplet photosensitizer shows no significant changes in the rate of disappearance of the double bonds. This particular polymer with a pendant chalcone unit was found to photocross-link at a high rate even in the absence of a photosensitizer and is of interest as negative photoresist [158].