Castor oil-based waterborne polyurethane/tunicate cellulose nanocrystals nanocomposites for wearable strain sensors.

In this study, tunicate cellulose nanocrystals (TCNCs) were introduced into castor oil-based waterborne polyurethane (WPU) to prepare bio-based nanocomposites through a simple solution blending method. The effect of TCNCs content on the particle size and stability of the composite dispersions, as well as the thermophysical and mechanical properties of the composite films were studied and discussed. The unique structure and properties of TCNCs, such as high crystallinity, large aspect ratio and high modulus, not only greatly improved the storage stability of WPU, but also showed significant reinforcing/toughening effects and excellent compatibility to WPU. By drip-coating silver nanowires (AgNWs) on the surface of the composite films, the flexible strain sensors were fabricated, which showed excellent sensitivity in monitoring human movement.

Scalable Production of Self-Toughening Plant Oil-Based Polyurethane Elastomers with Multistimuli-Responsive Functionalities.

Plant oils are becoming of high industrial importance due to the persisting challenges befalling with the utilization of fossil fuels. Thus, developing methodologies to produce multifunctional materials by taking advantage of the unique structure of plant oil is highly desired. In this study, castor oil served as a cross-linker and soft segments, by incorporating scalable rhodamine 6G derivatives, to systematically synthesize a series of smart polymers that possess self-toughening and multistimuli-responsive capabilities. The polyurethane elastomers showed 10 times and 60 times increases in tensile strength and toughness, respectively, in comparison with the unmodified polyurethane due to the existence of large amounts of hydrogen bonding, dynamic C-N spiro bonds, rigid benzene ring, and high cross-link densities. The novel polyurethane elastomers exhibited excellent reversible multichromic behaviors in response to light, pH, and mechanics. Notably, the resulting polyurethane elastomers exhibited ultrasensitive sustained photochromism with tunable white emission and rapid reversibility. This study provides a simple and effective strategy to utilize plant oil for multifunctional material preparation and paves the way to open access for application of plant oil-based products in a variety of industry applications, such as sensors, self-fitting tissue scaffolds, and switchable devices.

Semi-interpenetrating polymer networks prepared from castor oil-based waterborne polyurethanes and carboxymethyl chitosan.

A series of vegetable oil-based waterborne polyurethane composites were prepared through construction of novel semi-interpenetrating polymers network using carboxymethyl chitosan (CA) as the secondary polymer phase. The effects of CA contents on storage stability, and particle size distribution of the composite dispersions and thermal stability, mechanical properties and surface wettability of composite films were investigated and discussed. The results showed that the composite dispersions displayed excellent storage stability and the biomass contents of resulting films were high up to 80 %. A significant increase in crosslinking density and glass transition temperature of the composite films were observed as the CA contents increased, which was attributed to the increasing hard segment of films and strong hydrogen bonding interaction between polyurethanes and CA. This work provided a simple method to tailor the performance of environmentally friendly vegetable oil-based waterborne polyurethane, which could find application in the field of coatings, adhesives, ink and so on.