|Characterization of soy protein films with a durable water resistance-adjustable and antimicrobial surface|
Q. LIU (1), S. Li (2), H. Xiao (3), M. Thompson (4), Y. Zhang (5), C. Rempel (6) (1) Agriculture and Agri-Food Canada, Guelph, ON, Canada; (2) Agriculture and Agri-Food Canada, , Canada; (3) University of New Brunswick, , Canada; (4) McMaster University, , Canada; (5) University of Manitoba, , Canada; (6) Canola Council of Canada, , Canada.
The development of bio-based polymers from proteins has gained attention for the wide availability and renewable and biodegradable nature of protein. However, protein-based plastics have limited commercial applications because of several drawbacks, such as poor processability, brittleness, moisture sensitivity, and inferior mechanical and thermal properties. One of the objectives of this research work was to find a way to create functional soy protein isolate (SPI) films by immobilizing some functional polymers, such as pH or thermal sensitive, oxygen- or odour-resistant, and biocompatible polymers, on SPI films for different applications. In this study, a water resistant surface was first obtained by immobilizing hydrophobic copolymers (PSG) with functional groups on SPI films. X-ray Photoelectron spectrometer and Atomic Force Microscopy results showed that PSG copolymers were immobilized on the film by chemical bonding, and formed a rough surface with some bumps because of the segregation of two different phases on PSG copolymers. Water resistance of the modified films could be adjusted dramatically by further immobilizing different amounts of guanidine-based antimicrobial polymers (PHGH) on the resulting hydrophobic surface. The introduction of hydrophilic PHGH on the resulting surface generated many micropores, which potentially increased the water uptake of the modified films. Furthermore, the modified SPI films showed higher thermostability compared to the native SPI film and broad-spectrum antimicrobial activity by contact killing, attributed to the presence of PHGH on the surface. The modified SPI film with a multi-functional surface showed potential for applications in the packaging and medical fields.