Polymer of biological

Although the conditions of the polymerization reaction may be chosen to optimize the formation of one specific isomer, it is typical in these systems to have at least some contribution of all possible isomers in the polymeric product, except in the case of polymers of biological origin, like natural rubber and gutta-percha. 

Dichromated Resists. The first compositions widely used as photoresists combine a photosensitive dichromate salt (usually ammonium dichromate) with a water-soluble polymer of biologic origin such as gelatin, egg albumin (proteins), or gum arabic (a starch). Later, synthetic polymers such as poly(vinyl alcohol) also were used (11,12). Irradiation with uv light (X in the range of 360—380 nm using, for example, a carbon arc lamp) leads to photoinitiated oxidation of the polymer and reduction of dichromate to Ct(III). The photoinduced chemistry renders exposed areas insoluble in aqueous developing solutions. The photochemical mechanism of dichromate sensitization of PVA (summarized in Fig. 3) has been studied in detail (13). 

Cohn WE (1969) Representation of macromolecules and polymers of biological importance. J Chem Doc 9 235-241... 

Ikada Y (1994) In Shalaby SW, Ikada Y, Langer R, Williams J (eds) Interfacial biocom-patibility in polymers of biological and biomedical significance. ACS Symposium Series No. 540. American Chemical Society, Washington, D.C., pp 35-48... 

Fi Y and Spencer HG. Polymers of Biological and Biomedical Significance, Washington DC American Chemistry Society, 1994. 

Shalaby, S.W., et al. Polymers of Biological Biomedical Significance, ACS Symp. Ser. American Chemical Society Washington, DC, 1994 540. 

Four billion years ago the molecular building blocks of life had been synthesized, and these molecules must have become locally concentrated on surfaces and through self-selection as they assembled into vesicles and polymers of biological interest. Yet accumulations of organic molecules, no matter how highly selected and intricately organized, are not alive unless they also possess the ability to reproduce. 

Roweton, S. L. and Shalaby, S. W., Microcellular Foams, in Polymers of Biological and Biomedical Significance, Shalaby, S. W., Ikada, Y., Langer, R. and Williams, J. Eds., Vol. 520, ACS Symposium Series, American Chemical Society, Washington, DC, 1993. 

POLYMERS OF BIOLOGICAL AND BIOMEDICAL SIGNIFICANCE Table I. Transdermal Products... 

---