engleski

Influence of self-assembly of the bis(amino acid) fumarate on polymerization induced by gamma and ultraviolet rays

Supramolecular gels are a new class of self- assembled nanomaterial which design is a great challenge in the past decades because of their gel properties, specific applications, and preparation of new materials. [1] We investigated the influence of self-assembly organogelators [2, 3] on polymerisation in gels by UV and gamma irradiation. For UV irradiation we used high-pressure Hg lamp (100W) and photoinitiator benzophenone and for gamma irradiation using 60Co source at a total dose of 200 kGy and the dose rate of 14 kGy/hGy min- 1. Synthesis part of this work was to prepare a methyl ester of bis(Leu)fumarate and vinyl esters of bis(L-Leu or L-Val)fumarate (1. and 2.) by the reaction of fumaryl chloride with vinyl ester of the appropriate amino acid. Amino acid vinyl esters were prepared by the Pd-catalyzed transvinylation with vinyl acetate. These compounds are gelator of various organic solvent. After preparation of supramolecular gels of bis(Leu or Val)fumarate in toluene, the resulting material was exposed to UV or gamma rays.The obtained materials after irritation are polymers with a different network pattern of bis(L-Leu)fumarate and bis(L-Val)fumarate as a direct link of different self-assembly. Morphological study by SEM shows that the morphology of gel-network and polymer-network did not change significantly upon polymerization as confirm of the initial self-organized aggregates. Using FTIR spectroscopy data for solid matter and polymer matter we noticed that the characteristic stretching at 996 cm-1 (ascribed to fumaryl) and 947 cm-1 (characteristic for vinyl esters) are disappearing. Bis(Leu)fumarate polymer using UV irradiation mostly polymerizable through fumaric double bound but bis(Val)fumarate polymer through vinyl esters. UV irradiation of the methyl ester of bis(L-Leu)fumarate in a solution gave cyclobutane ring in [2+2] cycloaddition reaction.

supramolekularni gelovi ; polimerizacija ; samoorganizacija

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