A smart gating nanocellulose membrane showing selective separation and self-cleaning performance

Temperature-responsive gating chitosan-based microcapsules for controlled release of urea fertilizers

Polysaccharides-based smart fertilizers are essential for promoting plant growth, yet significant challenges exist in achieving stable structures and synchronizing nutrient release and plant growth. This study developed a temperature-responsive gating chitosan-based microcapsule (CTSMC-g-PNIPAM) by grafting N-isopropyl acrylamide (NIPAM) onto chitosan microcapsules (CTSMC) via atom transfer radical polymerization (ATRP). The interfacial crosslinking of chitosan (CTS) and terephthalendehyde (TPA) formed the CTSMC matrix with a hollow chamber structure and ensured stability. CTSMC-g-PNIPAM exhibited reversible temperature-responsive gating properties and sustained release behavior, and the PNIPAM chains acted like gating switches. Below the low critical solution temperature (LCST) (25 °C), the PNIPAM chains stretched and the gating switch closed, slowing down the release rate. Above the LCST (40 °C), the PNIPAM chains contracted and the gating switch opened, accelerating the release rate. The release behaviors of CTSMC-g-PNIPAM in soil indicated that the gating microcapsule effectively prolonged the release of urea. Moreover, the cumulative release of CTSMC-g-PNIPAM at 40 °C was significantly higher than at 25 °C. The first-order kinetic and Korsmeyer-Peppas model indicate that the urea release involves concentration gradient diffusion and skeleton dissolution. Compared with pure urea, urea@(CTSMC-g-PNIPAM) increased the growth status of maize, suggesting a promising strategy for smart fertilizers.

Smart Cellulose-Based Janus Fabrics with Switchable Liquid Transportation for Personal Moisture and Thermal Management

The Janus fabrics designed for personal moisture/thermal regulation have garnered significant attention for their potential to enhance human comfort. However, the development of smart and dynamic fabrics capable of managing personal moisture/thermal comfort in response to changing external environments remains a challenge. Herein, a smart cellulose-based Janus fabric was designed to dynamically manage personal moisture/heat. The cotton fabric was grafted with N-isopropylacrylamide to construct a temperature-stimulated transport channel. Subsequently, hydrophobic ethyl cellulose and hydrophilic cellulose nanofiber were sprayed on the bottom and top sides of the fabric to obtain wettability gradient. The fabric exhibits anti-gravity directional liquid transportation from hydrophobic side to hydrophilic side, and can dynamically and continuously control the transportation time in a wide range of 3-66 s as the temperature increases from 10 to 40 °C. This smart fabric can quickly dissipate heat at high temperatures, while at low temperatures, it can slow down the heat dissipation rate and prevent the human from becoming too cold. In addition, the fabric has UV shielding and photodynamic antibacterial properties through depositing graphitic carbon nitride nanosheets on the hydrophilic side. This smart fabric offers an innovative approach to maximizing personal comfort in environments with significant temperature variations.

Nanocellulose-based membranes with pH- and temperature-responsive pore size for selective separation

Smart gating membranes have drawn much attention due to the controllable pore structure. Herein, a smart gating membrane with dual responsiveness was prepared from bacteria cellulose (BC) grafted with pH- and temperature-responsive polymers. By external stimulation, the average pore size of the membrane can be controlled from 33.75 nm to 144.81 nm, and the pure water flux can be regulated from 342 to 2118 L·m-2·h-1 with remarkable variation in the pH range of 1-11 and temperature range of 20-60 °C. The adjustability of pore size is able to achieve the gradient selective separation of particles and polymers with different sizes. In addition, owing to the underwater superoleophobicity and the nanoscale pore structure, the membrane separation efficiencies of emulsified oils are higher than 99 %. Moreover, the controllable pore size endows the membrane with good self-cleaning performance. This nanocellulose-based smart gating membrane has potential applications in the fields of controllable permeation, selective separation, fluid transport, and drug/chemical controlled release systems.

A novel salt-barrier method of preparation flexible temperature resistant full-component nanocellulose membranes

With the simplification and diversification of separation technologies, nanocellulose membranes have become widely used as insulating materials. Recently, study of nanocellulose membrane modification has become a hot topic. However, the application of nanocellulose membrane has been limited due to their inadequate heat resistance and flexibility. Herein, based on the pyrolytic and thermoplastic properties of cellulose, we innovatively introduced a salt barrier scheme to regulate the degree of hydrogen bonding and thermoplastic bonding between fibers. This was achieved by adding a salt barrier agent, NaCl, in the middle of the nanocellulose to prepare and obtain flexible, high-temperature-resistant nanocellulose film materials. The full-component cellulose films thus prepared exhibited high tensile strength (8 MPa), excellent flexibility (105 mN), high electrical breakdown strength (67 KV/mm), and volume resistivity meeting the standard of insulation materials (3.23 × 1013 Ω·m). This scheme adheres to the principles of low cost, green, non-toxic and non-hazardous, providing a brand new approach for the research and development of high temperature resistant cellulose membrane materials, which is of significant commercial value and industrialization prospect.