Effect of oleic purity on the chemical structure, thermal and rheological properties of bio-based polymers derived from high oleic cottonseed oil via RAFT polymerization

Vegetable oils are natural products, and their compositions and quality mainly rely on the plants, seasons, and growing conditions. It seems to be obvious that the fatty acid compositions from vegetable oils can impact on the properties of resulting polymer materials made from them, however, it is rarely discussed. This study reports how the oleic purity influences the chemical, thermal and rheological properties of the corresponding bio-based polymers derived from cottonseed oil. Two cottonseed oil sources including a commercially available cottonseed oil and a high oleic cottonseed oil were chosen to prepare samples with different oleic purity levels using the urea inclusion methodology. The oils with different oleic purity levels were subsequently transformed to the cottonseed oil-based methacrylate reactive monomers with various oleic purity via an esterification reaction at room temperature. The monomers were then polymerized via Reversible Addition Fragmentation chain Transfer, RAFT, polymerization in the presence of a RAFT agent. A pure oleic acid source and the conventional free radical polymerization method were used for comparison. The chemical structures of synthesized bio-based monomers and polymers with different oleic content were confirmed using nuclear magnetic resonance, Fourier transform infrared spectroscopy, and characterized through gel permeation chromatography, thermogravimetric analysis and differential scanning calorimetry. The results demonstrated significant influence of oleic purity, the proportion the saturated palmitic and unsaturated linoleic in the oils on the properties of the corresponding bio-based RAFT polymers. The RAFT polymer derived from commercially available cottonseed oil had a higher glass transition temperature, lower viscosity, and less thermal resistance than that of RAFT polymer derived from high oleic cottonseed oil. The ramie fabric coated by the synthesized bio-based RAFT polymer from high oleic cottonseed oil displayed a hydrophobic surface with a water contact angle of 110°.