Self-Healing and Reprocessable Terpene Polysiloxane-Based Poly(thiourethane-urethane) Material with Reversible Thiourethane Bonds.

Polyurethane materials will come into contact with different solvents in daily life, and at the same time, they will be subject to different degrees of collision, wear and tear. Failure to take corresponding preventative or reparative measures will result in a waste of resources and an increase in costs. To this end, we prepared a novel polysiloxane with isobornyl acrylate and thiol groups as side groups, which was further used in the preparation of poly(thiourethane-urethane) materials. Thiourethane bonds generated by the click reaction of thiol groups with isocyanates endow poly(thiourethane-urethane) materials with the ability to heal and reprocess. Isobornyl acrylate with a large sterically hindered rigid ring promotes segment migration, accelerating the exchange of thiourethane bonds, which is beneficial to the recycling of materials. These results not only promote the development of terpene derivative-based polysiloxanes but also show the great potential of thiourethane as a dynamic covalent bond in the field of polymer reprocessing and healing.

A tough, healable, and recyclable conductive polyurethane/carbon nanotube composite.

Recently, conductive composites have been used in flexible electronic devices and have attracted attention. The integration of self-healing, high sensitivity, large tensile strength, environmental stability, and easy recyclability into conductive composites is very desirable yet challenging. Hence, a conductive composite as a flexible strain sensor with a self-healing and recyclability is facilely developed, with a polyurethane (PU) elastomer bearing dynamic boronic ester as the polymer matrix and carbon nanotubes (CNTs) as a conductive filler. Due to the dynamic boronic ester bond and hydrogen bond, the prepared polyurethane conductive composite has good self-healing and mechanical properties. It not only has a high healing efficiency of 78 % but also has a tensile strength of 15.4 MPa and an elongation at break of 420 %. In addition, the prepared conductive composite has high conductivity (0.57 mS/cm) and sensitivity. As a wearable sensor, it can identify human activities in all directions, such as elbow and finger bending, speaking, and facial changes. Consequently, the polyurethane conductive composite prepared in this study exhibited wonderful application potential in wearable electronic devices such as self-healing strain sensors.

Thermo-/pH-responsive preservative delivery based on TEMPO cellulose nanofiber/cationic copolymer hydrogel film in fruit packaging.

Hydrogels have great potential in food packaging. However, stimuli-responsive preservative delivery-based hydrogels for emerging active packaging have not yet been explored. Herein, Unprecedented pH/temperature-responsive hydrogel films for emerging active climacteric fruit packaging were developed based on TEMPO-oxidized nanofibrillated cellulose (TOCNFs) from wheat straw with food-grade cationic-modified poly(N-isopropyl acrylamide-co-acrylamide) (CPNIPAM-AM). TOCNF incorporation into CPNIPAM-AM revealed desirable enhancement of characterization, antimicrobial properties, and pH/thermal-responsive behaviour. In-vitro delivery and release mechanism studies with natamycin revealed the fastest release rates in preferred low pH media, up to 32.1 times higher than that under neutral conditions via anomalous diffusion. Applying a thermal stimulus increased natamycin release rates, providing 1.5-21% gradual-additional pulses by Fickian diffusion. The final hydrogel film showed efficient decay control in response to stimuli of the climacteric fruit environment with safe, recyclable, and feasible application demonstrating the significant potential to be used as an alternative-sustainable material for stimuli-triggered preservative delivery in climacteric fruit packaging.

Factors influencing the morphology and adsorption performance of cellulose nanocrystal/iron oxide nanorod composites for the removal of arsenic during water treatment.

The removal of arsenic from reservoirs is a matter of great concern in many parts of the world. Since adsorption is one of the most effective methods for treating arsenic-containing media, iron oxide nanorods were prepared using cellulose nanocrystals (CNs) as a template to remove this harmful metal from aqueous solutions. X-ray diffraction (XRD) analysis showed that Fe(OH)3 was formed in the initial stage of the hydrothermal reaction, and Fe(OH)3 was transformed into Fe2O3 as the hydrothermal reaction proceeded. Transmission electron microscopy (TEM) analysis showed that the length of the iron oxide nanorods was nearly 200 nm, and the width was 10 nm. Moreover, adsorption property studies showed that the maximal amount of As(III) and As(V) adsorption, corresponding to levels of 13.866 mg/g and 15.712 mg/g, occurred at pH levels of 7 and 3, respectively. The adsorption process conformed to the quasi-second-order kinetic and Langmuir adsorption isotherm models, indicating that the adsorption process consists of a chemical adsorption of monolayers. The results indicate that this composite can be used as a potential adsorbent for treatment of water containing harmful substances.

Preparation and Characterization of Cellulose Grafted with Epoxidized Soybean Oil Aerogels for Oil-Absorbing Materials.

The absorbent materials synthesized from biosources with low cost and high selectivity for oils and organic solvents have attracted increasing attention in the field of oil spillage and discharge of organic chemicals. We developed a convenient surface-grafting method to prepare efficient and recyclable biobased aerogels from epoxidized soybean oil (ESO)-modified cellulose at room temperature. The porous network-like structure of the cellulose aerogel was still fully retained after undergoing hydrophobic modification with ESO. Moreover, the modified aerogels possessed excellent hydrophobicity with a water contact angle of 132.6°. Moreover, the absorbent ability of the hydrophobic cellulose aerogels was systematically assessed. The results showed that modified aerogels could retain more than 90% absorption capacity even after 30 absorption-desorption cycles, indicating that the ESO-grafted cellulose aerogels have practical applications in the oil-water separation from industrial wastewater and oil-leakage removal.