Comparative analysis of cellulose nanocrystals and cellulose nanofibrils on the physico?chemical properties of polyvinyl alcohol/chitosan blend for sustainable food packaging
Copolymerization of bio?based alkyl methacrylate (C13MA) with glycidyl methacrylate at moderate temperature is done. The synthesized copolymer is treated with carbon dioxide to form cyclic carbonate functional groups which then react with a bioderivable diamine (1,10 diaminodecane) to form a network crosslinked through urethane linkages. The networks show a wide range of Young's moduli from 0.1 to 71.9?MPa, depending on the concentration of urethane linkages in the network.AbstractA hybrid methodology is used to combine the favorable properties of non?isocyanate polyurethanes (NIPUs) in the side chains with poly(methacrylates) as the backbone into thermoset hybrid resins with hydroxyurethane linkages (HNIPU)s. Using NIPUs linkages avoids the use of toxic isocyanates in the poly(urethane) segments. The backbone is synthesized from cyclic carbonated copolymer templates derived from atom transfer radical polymerization (ATRP) of an alkyl methacrylate (C13MA with average side?chain length of 13)/glycidyl methacrylate (GMA) mixtures (initial GMA mol fraction?=?0.1–0.4). The resulting flexible resins with pendent epoxy functional groups were subsequently carbonated and then reacted with 1,10?diaminodecane (90°C, 24?h) to form rigid side chains via hydroxyurethane linkages. Manipulating template functionality (2–11 urethane linkages out of 35 backbone units) yielded crosslinked networks with Young's moduli from 0.1 to 71.9?MPa while decreasing tensile elongation at break from 105% to 10%. Swelling ratios (SR) of the networks in tetrahydrofuran (THF) decrease as urethane linkage concentration increases, indicating tighter networks, consistent with the rheologically obtained molecular weight between crosslinks. Gel content indicated less than 15% of the networks are soluble in THF. The HNIPU networks derived show their ready tunability by simply changing the precursor functionality.