Biodegradation of Styrene-Butadiene-Styrene Coploymer via Sugars Attached to the Polymer Chain

A synthetic method was developed to chemically attach few molecules of simple sugars like glucose, mannose, galactose, maltose and xylose (0.09 - 0.37 wt%) and with quaternary nitrogen pendants (0.42 - 0.46 atomic%) along the polybutadiene section of polystyrene-block-polybutadiene-block-polystyrene (SBS) block copolymer. These functionalized SBS copolymers were evaluated for biodegradation using the fungal culture Aspergillus niger NCIM 1025 (ATCC 9642) and bacterial culture Pseudomonas sp. NCIM 2220, and for antimicrobial properties using bacteria E. coli DH5α and Bacillus subtilis and yeasts Pichia stipitis NCIM 3497 and P. stipitis NCIM 3499. It was conclusively demonstrated that these modified SBS block copolymers were significantly more biodegradable than the unmodified SBS; the observed weight loss after biodegradation was ~4 - 14-fold for bacterial and ~7 - 36-fold for fungal cultures with respect to the sugar content of modified SBS. Preliminary studies on antimicrobial properties of these biodegradable polymers showed a 4% - 24% decrease in growth of the microorganisms E. coli and Bacillus subtilis studied.