A new article out of a collaboration between Professor Ning Yan and Dr. Dan Li has been published in the Carbohydrate Polymers Journal written by Yunxia Yang, Dan Li, Ning Yan and Fu Guo.

You can find the article here

Abstract

Cellulose nanofibrils (CNFs) are derived from biomass and have significant potential as fossil-based plastic alternatives used in disposable electronics. Controlling the nanostructure of fibrils is the key to obtaining strong mechanical properties and high optical transparency. Vacuum filtration is usually used to prepare the CNFs film in the literature; however, such a process cannot control the structure of the CNFs film, which limits the transparency and mechanical strength of the film. Here, direct ink writing (DIW), a pressure-controlled extrusion process, is proposed to fabricate the CNFs film, which can significantly harness the alignment of fibrils by exerting shear stress force on the filaments. The printed films by DIW have a compact structure, and the degree of fibril alignment quantified by the small angle X-ray diffraction (SAXS) increases by 24 % compared to the vacuum filtration process. Such a process favors the establishment of the chemical bond (or interaction) between molecules, therefore leading to considerably high tensile strength (245 ± 8 MPa), elongation at break (2.2 ± 0.5 %), and good transparency. Thus, proposed DIW provides a new strategy for fabricating aligned CNFs films in a controlled manner with tunable macroscale properties. Moreover, this work provides theoretical guidance for employing CNFs as structural and reinforcing materials to design disposable electronics.

A new article from Ning Yan’s lab has been published in Chemical Engineering Journal written by Haonan Zhang, Yanchen Zhu, Tongtong Fu, Cheng Hao, Yang Huang, Hao Ren, Ning Yan, Huamin Zhai. You can find the article HERE.

Click here to see the full article until April 25, 2024

Abstract

Soft electronics have garnered significant interests owing to their distinctive qualities. However, their practical utilizations are still limited by their generally poor mechanical properties, environmental concerns, and incompatibility. Here, we present a unique hierarchical nanoarchitectural design of dynamic noncovalent supramolecular zipper to achieve synergistic enhancement of both mechanical strength and toughness in organogels. By building lignin-carbohydrate complexes nanoparticles (LCCNPs)-based sliding zippers within the interpenetrating polymer networks (IPN) formed by in-situ regenerated cellulose nanofibrils (CNFs) and polyvinyl alcohol (PVA) molecular chains, the lignocellulosic organogels demonstrated excellent mechanical properties, shape recovery performances, and strain-stiffening behaviors. The ultimate tensile strength increased by 11-fold, reaching 8.29 MPa, while the toughness also had an increase of 24-fold, reaching 23.8 MJ/m³ at the same time, comparing to those of the PVA hydrogel. These novel organogels also exhibited exceptional anti-freezing (<-150 °C), anti-dehydration, transparency, UV-shielding, and biodegradable properties. The assembled wearable sensor using the organogels were able to monitor human motion status and physiological signals with a tunable conductivity (up to 5.14 S/m), a high sensitivity (a maximum gauge factor of 5.62) and long cyclic stability (2000 cycles). This novel nano-structural design approach showcases a facile and versatile platform for constructing the next-generation high performance bio-based soft electronics.

A new article out of a collaboration between Dr. Ning Yan and Dr. Jing Chen’s labs has been published in Chemical Engineering Journal written by Xiaobo Xu, Xiaozhen Ma, Minghui Cui, Honglong Zhao, Nathan E. Stott, Jin Zhu, Ning Yan, and Jing Chen.

You can find this article HERE.

Abstract

In this study, a novel bio-based diol containing imine dynamic bonds (Vanp2) were synthesized using vanillin and bio-based 1,5-pentanediamine. Vanp2 was then introduced into the cross-linking network of betulin-based polyurethanes to obtain betulin-based polyurethanes containing covalent adaptive networks (CANs). Imine dynamic bonds within CAN endowed these betulin-based polyurethanes with self-healing, re-processability, degradability, and editable shape memory functionalities. Meanwhile, the mechanical and thermal properties of these fully bio-based polyurethane materials were characterized. The maximum tensile strength reached 9.5 MPa, while the maximum strain at break was 248 % and the maximum toughness was 13.2 MJ/m³. Thermal decomposition temperature was greater than 300 °C. Since the imine structure could be dissociated under acidic conditions, these polyurethanes could be rapidly degraded in a mixed acid solution at 50 °C in 4 h. This study demonstrated a strategy for synthesizing betulin-based polyurethane elastomers containing CAN using only bio-based feedstock.

A new article out of a collaboration between Dr. Ning Yan and Dr. Jing Chen’s labs has been published been published in ACS Applied Polymer Materials written by Xiaobo Xu, Xiaozhen Ma, Xiaolin Wang, Jin Zhu, Jinggang Wang, Ning Yan, and Jing Chen.

You can find this article HERE.

Abstract

Using sustainable biomass feedstock to prepare biobased chemical products is attracting increasing attention. Betulin is a natural cyclic aliphatic diol that can be extracted in large quantities from the bark of birch trees. In this study, a series of bio-based polyurethane (PU) elastomers with excellent mechanical properties, solvent resistance, and thermal stability were synthesized under catalyst-free conditions using betulin and castor oil (CO) as the bio-based polyols. The chemical structure and properties of the bio-based PU elastomers were systematically investigated according to the effect of the hydroxyl ratio between betulin and CO. Due to the presence of abundant hydrogen bonds and rigid ring planes in the PU structure, and a higher cross-link density, the obtained PU elastomers had excellent mechanical properties. They achieved a maximum tensile strength of 31.6 MPa with the tensile strain reaching more than 200% and were able to withstand 1 × 10⁵ times their weight. The thermal decomposition temperature of the betulin-derived PUs was over 300 °C. This study showcased a strategy to synthesize sustainable high-performance PU materials with a high biomass content (>75%).

A new article out of a collaboration between Dr. Ning Yan and Dr. Jing Chen’s labs has been published in Chemical Engineering Journal written by Huihui Wang, Cheng Hao, Tong Shu, Pandeng Li, Tianyi Yu, Longjiang Yu, and Ning Yan.

You can find the article HERE.

Abstract

Janus fabrics are often used for oil/water separation, fog-harvesting, and moisture-wicking clothing due to their unidirectional liquid transport (ULT) ability. However, Janus fabrics are usually mono-functional, and the fabrication process is complex. Moreover, the chemicals used are not green. Herein, a versatile Janus fabric from ramie with ULT, flame retardancy, and moisture-wicking features was fabricated using a facile and sustainable method. Chitosan and phytic acid were rapidly deposited on the surface of fabrics via electrostatic gravitation, and polydivinylbenzene was then used as coating after in situ polymerization. Reverse wettability was achieved on two sides of the Janus ramie fabric after the UV irradiation of one of the sides, which endowed the fabric with ULT ability. Janus ramie fabric exhibited a comparable water vapor transmission rate to that of pristine ramie fabric but a higher water evaporation rate because of its ULT ability, indicating an improved moisture-wicking ability. Furthermore, the Janus ramie fabric displayed a good oil/water mixture separation performance with a separation efficiency of over 98% and good mechanical abrasion and chemical resistance. More importantly, the Janus ramie fabric showed excellent flame retardancy, a self-extinguishing ability, and a high limiting oxygen index of 34.5%, and its heat release rate, heat release capacity, and total heat release rate were significantly lower than those of pristine fabric. Therefore, this versatile Janus ramie fabric demonstrates great potential for various practical applications.