Investigating the Effect of Ionic and Covalent Crosslinkers on the Properties of Marine-based Macroalgae Biofilm Composite

Macroalgae with nontoxicity, biodegradability and biocompatibility has attracted more attentions as a sustainable alternative towards petroleum-derived plastics. However, brittleness and high affinity towards water has limited marine-based macroalgae films to be widely used. Thus, this paper aims to compare the roles of calcium chloride as ionic cross-linker and acrylic resin as covalent cross-linker in agar-PEG plasticised biofilm composite. Agar biofilm composite with PEG 1000 40% were cross-linked with i) calcium chloride 1, 2, 3 and 4 (CaCl2/agar) wt/wt % at 2 or 4 min immersion time, and ii) acrylic resin at 10, 20, 30, 40 and 50 (acrylic resin/agar) wt/wt %. FTIR and TGA proved that CaCl2 and acrylic resin managed to cross-link agar-PEG films ionically and covalently respectively. In general, films cross-linked with CaCl2 produced highest affinity towards water than films cross-linked with acrylic resin. Highest tensile strength, highest tensile modulus and lowest elongation at break was achieved when films cross-linked with CaCl2. Films cross-linked with CaCl2 has higher degradation rate than films cross-linked with acrylic resin. In conclusion, different mode of cross-linking (ionic or covalent) imparted different properties on the agar-PEG film.