Category Archives: Journal Articles

New Article: Catalyst-Free Biodegradable Chitosan-Based Dual Dynamic Covalent Networks with Self-Healing and Flame-Retardant Properties

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A new article from Ning Yan’s lab has been published in ACS Sustainable Chemistry & Engineering written by Mohammad H. Mahaninia and Ning Yan.

You can find the article here

Abstract

Synthesizing covalent adaptable networks (CANs) from chitosan has been difficult due to its inherent insolubility in organic solvents. In this study, we report a facile approach for obtaining biobased flame-retarding CANs using chitosan as the starting material without dissolving it. These novel CANs were prepared via a dual cross-linking strategy in which chitosan consecutively reacted with citric acid and a vanillin-based cross-linker containing a flame-retarding moiety. The chitosan-based CANs attained dual dynamic bond-exchange sites resulting from generation of amide and ester linkages, which enabled them to perform self-healing and recyclability. They also possessed remarkable flame-retarding performance (e.g., limiting oxygen index of 41.5% and UL-94 V-0 rating), surpassing other chitosan-based flame retardants reported in the literature to date. By investigating the CAN’s response to fire in both gas and condensed phases, their flame-retarding mechanisms were uncovered. This study pinpoints a promising approach to make biobased, biodegradable, and multifunctional CANs from chitosan.

New Article: Self-healable, recyclable, and mechanically robust vitrimer composite for high-performance triboelectric nanogenerators and self-powered wireless electronics

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A new article from Ning Yan’s lab has been published in Nano Energy written by Araz Rajabi-Abhari, Pandeng Li, Majid Haji Bagheri, Asif Abdullah Khan, Cheng Hao, Nicolas R. Tanguy, Dayan Ban, Longjiang Yu, and Ning Yan.

You can find the article here

Abstract

With growing concerns about sustainability, there has been significant research interest in fabricating triboelectric nanogenerators (TENGs) from materials capable of self-repair. Here, we presented a novel polyimine/graphite polypropylene (PI/GP) vitrimer composite as a tribo-positive material for harvesting biomechanical energy. The PI/GP exhibited mechanical robustness, self-healing properties after damage, and recyclability through physical or chemical methods. The GP provided a high dielectric constant, charge transport paths, and desirable surface roughness, resulting in an outstanding TENG performance at an optimized addition level of 30 wt% in the composite (PI/GP30). Under a force of 15 N and a frequency of 6 Hz, the PI/GP30 TENG generated a power density of 2571 mW/m². Moreover, a PI/GP30 TENG device with an area of 49 cm2 was able to generate a remarkable output voltage of nearly 1325 V, at a frequency of 6 Hz and under a vertical force of 15 N. Additionally, the PI/GP30 TENG device produced a peak-to-peak voltage of 1250 V, and an outstanding current of around 2 mA by hand tapping with a force of 35–40 N. The PI/GP30 TENG was utilized for real-life applications, including a triboelectric watchband for a self-powered watch, and wireless data transmission. Furthermore, the PI/GP30 TENG demonstrated excellent self-healing and recyclability, and these properties were examined in a mousepad power generator. This study highlights the excellent promise of PI/GP vitrimer composite for fabricating high-performance, mechanically robust, self-healable, and recyclable TENGs, enabling their applications in green biomechanical power generators and wearable and wireless communication devices.

New Article: Mechanical and Insulation Performance of Rigid Polyurethane Foam Reinforced with Lignin-Containing Nanocellulose Fibrils

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A new article from Ning Yan’s lab has been published in Polymers written by Kabirat O. Bello and Ning Yan. 

You can find the article here.


Abstract

Isocyanates are critical components that affect the crosslinking density and structure of polyurethane (PU) foams. However, due to the cost and hazardous nature of the precursor for isocyanate synthesis, there is growing interest in reducing their usage in polyurethane foam production—especially in rigid PU foams (RPUF) where isocyanate is used in excess of the stoichiometric ratio. In this study, lignin-containing nanocellulose fibrils (LCNF) were explored as mechanical reinforcements for RPUF with the goal of maintaining the mechanical performance of the foam while using less isocyanate. Different amounts of LCNF (0–0.2 wt.%) were added to the RPUF made using isocyanate indices of 1.1, 1.05, 1.0, and 0.95. Results showed that LCNF served as a nucleating agent, significantly reducing cell size and thermal conductivity. LCNF addition increased the crosslinking density of RPUF, leading to enhanced compressive properties at an optimal loading of 0.1 wt.% compared to unreinforced foams at the same isocyanate index. Furthermore, at the optimal loading, LCNF-reinforced foams made at lower isocyanate indices showed comparable stiffness and strength to unreinforced foams made at higher isocyanate indices. These results highlight the reinforcing potential of LCNF in rigid polyurethane foams to improve insulation and mechanical performance with lower isocyanate usage.

New Article: Lignin-based adaptable covalently cross-linked fabric for flexible sensors

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A new article out of a collaboration between Dr. Ning Yan and Dr. Jing Chen’s labs has been published in Materials Chemistry Frontiers written by Xiaozhen Ma, Xiaolin Wang, Honglong Zhao, Minghui Cui, Xiaobo Xu, Fangfang Kong, Peng Chen, Ning Yan, Jin Zhu and Jing Chen.

You can find the article here

Abstract

In this study, we successfully upcycled a novel lignin-based covalent adaptable polyurethane elastomer (LPUE) that we previously synthesized into a graphene-composited covalent adaptable lignin-based polyurethane fabric (LPUF). This fabric exhibited outstanding solvent resistance, toughness (LPUF-0 with a tensile strength of 29.1 ± 1.6 MPa, an elongation at break of 653 ± 67%, and a toughness of 103 ± 3.8 mJ m−3), and deformation responsiveness. These results not only open up new possibilities for improving covalently adaptable networks in fabrics, but also pave the way for developing solvent-resistant, wearable sensing devices.

New Article: A new 3D printing strategy by enhancing shear-induced alignment of gelled nanomaterial inks resulting in stronger and ductile cellulose films

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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.

New Article: Degradable and Biobased Covalent Adaptable Networks for Light Controllable Switch

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A new article out of a collaboration between Dr. Ning Yan and Dr. Jing Chen’s labs has been published in the ACS Sustainable Chemistry & Engineering written by Xiaozhen Ma, Xiaolin Wang, Honglong Zhao, Minghui Cui, Xiaobo Xu, Fangfang Kong, Peng Chen, Ning Yan, Jin Zhu and Jing Chen.

You can find the article here

Abstract

In this study, we successfully synthesized lignin-based covalent adaptable polyurethane networks containing lignin-graphite nanosheet composite particles with a light controllable positive temperature coefficient (LPTC) effect. The use of lignin facilitated the direct exfoliation of graphite, thus overcoming the challenge of achieving a uniform dispersion of conductive fillers in the polymer matrix. The exfoliated graphite had a thickness of approximately 3.0 nm, which was equivalent to three to five layers of graphene. By preparing lignin-based covalent adaptable polyurethane without graphite composite particles (LPU) and lignin-based covalent adaptable polyurethane with graphite composite particles (LPU-G), we achieved remoldable properties and a high LPTC intensity for LPU-G. LPU-60G (60 represents the mass fraction of lignin-graphite nanosheets in polyols) exhibited an excellent LPTC effect, with sharp increases in resistance under light, particularly under near-infrared light (NIR), enabling the control of the current in circuits. Additionally, both LPU and LPU-G demonstrated degradability by slowly degrading in a PBS solution while rapidly degrading in an alkaline solution. Overall, the LPU-G synthesized in this study displayed superior stability in the LPTC effect and possessed degradability, providing a promising avenue for the future development of smart materials.

New Article: Robust and ultra-tough lignocellulosic organogel with zipper-like sliding noncovalent nanostructural design: Towards next-generation bio-derived flexible electronics

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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.

New Article: Bio-based pH-responsive microcapsules derived from Schiff base structures for acid rain protection

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A new article from Ning Yan’s lab has been published in Composites Part B: Engineering written by Qin Chen, Haonan Zhang, Cheng Hao, Limin Guo, Long Bai, Jiyou Gu, and Ning Yan. You can find the article here.

Click here to see the full article until April 03, 2024

Abstract

Self-healing technology based on microcapsules (MCs) holds great promise for preventing material performance deterioration, extending material lifespan, and reducing maintenance costs. In this study, a novel pH-responsive MC with a vanillin-based Schiff base polyurea shell and an isocyanate core was successfully prepared using interfacial polymerization. Vanillin-based Schiff base-containing triamines were synthesized, and their existence was confirmed through ATR-FTIR and 1H NMR analyses. The core-shell structures of the MCs were identified using FTIR and TGA. Additionally, the excellent response of the MCs to acid rain was demonstrated by determining the core content and recording optical images of the healing agent release process, with the fastest release rate observed at a pH of 2.98. According to the FTIR and TGA results, the release of the healing agent was continuous rather than occurring once. The MCs were incorporated into outdoor building materials (OBMs) (carbon steel, concrete, and wood) as a coating in conjunction with paint or polyvinyl alcohol (PVA). The pressure response, hydrogen bonding response, and hydrophobicity of the composite coating were assessed using SEM and water contact angle measurements. After subjecting the materials to 50 cycles of acid rain wet-dry tests (pH = 5.03), the carbon steel remained largely rust-free, whereas untreated carbon steel could only withstand a single cycle. Consequently, this study highlights a novel green structure and scalable manufacturing process for functional self-healing MCs, with significant implications for the advancement of stimulus-responsive composite materials and the realization of a sustainable and environmentally friendly economy.

New Article: Superhydrophobic polyurethane foam based on castor oil and lignin with SiC nanoparticles for efficient and recyclable oil-water separation

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A new article out of a collaboration between Dr. Ning Yan and Dr. Jing Chen’s labs has been published in the Journal of Water Process Engineering written by Wanrong Lv, Jialong Wu, Xiaozhen Ma, Xiaobo Xu, Xiaolin Wang, Jin Zhu, Ning Yan, and Jing Chen.
You can find the article here.

Click here to see the full article until March 29, 2024

Abstract

Superhydrophobic polyurethane foam has great potential to be used as adsorbent for cleaning up oil spills. In this study, lignin and castor oil were used as alternative resources to petroleum-based raw materials for the production of degradable polyurethane foams for oil spill treatment. SiC was first modified by 1H, 1H, 2H, 2H-perfluorododecyltrichlorosilane (FDTS) to obtain F-SiC. F-SiC was superhydrophobicity with an irregular crystalline structure of diameters ranging from 20 to 500 nm. It was incorporated into the matrix of lignin and castor oil derived polyurethane foam. With the addition of F-SiC, the water contact angle of the foam increased to 151.7 °C to render the foam superhydrophobic. After 100 cycles of mechanical compression, the foam showed a good elastic recovery ability. It is shown in SEM that F-SiC was distributed on the foam skeleton. Under 1 KW/m2 sunlight intensity, the temperature of the foam went up to 88.8 °C. On top of that, the foam showed excellent self-cleaning and oil-absorbing properties. It degraded within 4 h in alkaline solutions. Therefore, these castor oil and lignin derived bio-based polyurethane foams possess good mechanical stability, fast oil absorption, and alkaline degradability which has good application prospects in oil spill cleanup.

New article: Fully biomass-derived polyurethane based on dynamic imine with self-healing, rapid degradability, and editable shape memory capabilities

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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.