New Article: Multifunctional superhydrophilic/underwater superoleophobic lignin-based polyurethane foam for highly efficient oil-water separation and water purification

A new article out of a collaboration between Dr. Ning Yan and Dr. Jing Chen’s labs has been published in Separation and Purification Technology Journal written by Jing Chen, Jialong Wu, Yinyan Zhong, Xiaozhen Ma, Wanrong Lv, Honglong Zhao, Jin Zhu, and Ning Yan.

You can find the article here.

Abstract

Superwettability can affect the performance of oil separation from water during the treatment of oily wastewater. Among various types of materials developed for cleaning oil pollution, foam is a popular choice due to its attractive lightweight properties and adjustable porosities. Foams with superwetting surfaces (superhydrophilic/superoleophobic underwater) are ideal for oil/water separations. In this study, lignin-based polyurethane foams (LPUFs) were synthesized first, and then polydopamine particles were deposited on the surface of the foam by in situ polymerization under weak alkaline conditions to increase its surface roughness. Afterwards, phytic acid was used to modify the foam to achieve surface superhydrophilicity and underwater superoleophobicity. Successful loading of polydopamine (PDA) particles and coating of phytic acid (PA) onto the foam was demonstrated by SEM, EDS, FTIR, XPS, and thermogravimetric analysis measurements. It was shown in the cyclic compression tests that LPUFs had good mechanical properties. Under 75 % compression strain, the maximum stress in the first cycle of LPUF/PDA/PA was 105.92 kPa. After 30 cyclic compression tests, the maximum stress of LPUF/PDA/PA under 75 % compression strain was 105.63 kPa, demonstrating a high mechanical stability. The contact angle of the foam modified by PDA and PA was 0° for water, 166.7° for chloroform, and 158.4° for hexane, which also demonstrated excellent underwater anti-oil adhesion performances. Oil-water separation tests by using PDA and PA modified lignin-based foam with mixtures of water and n-hexane, cyclohexane, toluene, and pump oil indicated a separation efficiency of over 99 % for the types of mixtures tested together with excellent repeatability. In addition, the PDA and PA modified lignin-based foams were able to adsorb 67.1 mg/g of methylene blue, 96.1 mg/g of rhodamine B, and 98.2 mg/g of copper sulfate. The lignin-based foam could completely degrade under weak alkaline conditions after usage. This study highlighted a novel strategy for synthesizing environmentally friendly high-performance adsorbents to efficiently treat polluted wastewater using lignin as a raw material.

New Article: Insights into the Interaction between Amylose-Rich Corn Starch and Maleic Anhydride in Imidazolium Chloride-Based Ionic Liquids

A new article from Ning Yan’s lab has been published in ACS Applied Polymer Materials written by Shrestha Roy Goswami, Sen Wang and Ning Yan.

The first 50 people to click here will have access to a free e-print of the final published article until January 2024.

Abstract

Starch maleates with a high degree of maleic anhydride (MA) substitutions (DS) are in-demand for producing advanced composites. High-DS maleates are synthesized in imidazolium chloride-based ionic liquids because they could sustain starch-MA esterification, the precise mechanism of which, however, is largely unknown. In this study, we mapped chemical shifts of imidazolium cations before and after MA was added to each of the three starch-[C2mim]Cl, starch-[Amim]Cl, and starch-[C4mim]Cl systems. [C4mim]+ and [Amim]+ cations were observed to form substantial H-bonds with hydroxyls of starch. These hydroxyls could further associate with MA, liberating the bound cations. The liberated [Amim]+ cations, unlike [C4mim]+ cations, could readily donate their C2–H protons to activated MA, providing high-DS maleates (DSNMR ≈ 0.1, DStitration ≈ 1.20). The insights gained from this study would benefit the development of maleates from a wide range of biopolymers and expedite the screening of ionic liquids with varying cation–anion combinations for high-DS maleate synthesis.

New Article: Eco-friendly recyclable high performance ramie yarn reinforced polyimine vitrimer composites

A new article from Ning Yan’s lab has been published in Chemical Engineering Journal written by Pandeng Li, Cheng Hao, Huihui Wnag, Tian He, Tong Su, Cong Lo, Longjiang Yu and Ning Yan.

Click here for the article.

Abstract

The huge and increasing amount of plastic waste harms wildlife and releases chemical hazards to the environment. Using cellulosic fibers to prepare natural fiber-reinforced plastic composites (NFRPCs) is a promising strategy to decrease plastic wastes and lower their negative impacts because cellulosic fibers are renewable, degradable, and conducive to carbon neutrality. However, the low tensile strength and recycling difficulty of NFRPCs prevent them from substituting nondegradable plastics on an industrial scale. This study prepared high-performance ramie yarn-reinforced polyimine vitrimer composites (RY-PI) that could be recycled both chemically and physically. The polyimine matrix formed a robust bonding interface with ramie yarn via hydrogen bonding. The tensile strength of RY-PI (144MPa) was superior to that of most NFRPCs available in the market and was the highest amongst the NFRPCS with the same fiber fraction (wt%). RY-PI was also lightweight and had good toughness, self-healing ability, moldability, durability to organic solvents, and moisture barrier resistance. A box prepared by four-layer RY-PI laminates could support more than 3,000 times its own weight. The RY-PI was closed-loop recycled through a chemical strategy without any loss of performance. More importantly, a highly efficient (11 minutes for each recycling), low-cost, and eco-friendly (without adding any chemicals) physical recycling method of RY-PI was demonstrated. RY-PI could be physically recycled at least 9 times without any loss of performance. The high performance and good recyclability of RY-PI make it a promising environmental-friendly alternative to many conventional plastic products to help achieve zero plastic waste.

New Article: Catalyst-Free Synthesis of Covalent Adaptable Network (CAN) Polyurethanes from Lignin with Editable Shape Memory Properties

A new article out of a collaboration between Dr. Ning Yan and Dr. Jing Chen’s labs has been published in Science of The Total Environment written by Xiaozhen Ma, Shuqi Li, Fan Wang, Jialong Wu, Yeyan Chao, Xu Chen, Peng Chen, Jin Zhu, Ning Yan and Jing Chen.

You can find the article here.

Abstract

Here a new strategy of catalyst-free direct synthesis of covalent adaptable network polyurethanes (LPUs) from lignin with editable shape memory effect is reported. Using unmodified lignin, PEG, and isocyanate under the condition of the isocyanate index less than 1.0 (NCO/OH <1.0), a variety of LPUs were obtained. When NCO/OH=0.8, a stable cross-linked network could be formed (ex. the gel content of LPU50-0.8 was 98 ± 0.3 %). The activation energy (Ea) value of LPUs was similar to that of polyhydroxyurethanes (PHUs), at around 110 kJ/mol. With an increase of lignin content, the LPUs showed a transition from ductile fracture to brittle fracture mode. And the mechanical properties of LPUs were significantly enhanced after extrusion processing, with the maximum modulus reaching 649 ± 26 MPa and the maximum toughness up to 9927 ± 111 kJ/m3. The improvement in mechanical properties was due to the homogenization of complex cross-linked network under the powerful external force of the extruder and the lignin that originally was free in the system participated in the exchange reactions. Moreover, LPUs could also be prepared continuously in one step by using an extruder as the reactor. In addition, LPU50-0.8 had an editable shape memory effect. This study developed a novel method for the synthesis of LPU from lignin with NCO/OH<1.0, showcasing new possibilities for value-added utilization of lignin, and expanding the bio-based products portfolio from biomass feedstock to help meet future green manufacturing demands.

New Article: Superhydrophobic lignin-based multifunctional polyurethane foam with SiO2 nanoparticles for efficient oil adsorption and separation

A new article out of a collaboration between Dr. Ning Yan and Dr. Jing Chen’s labs has been published in Science of The Total Environment written by Jialong Wu, Xiaozhen Ma, Pitchaimari Gnanasekar, Fan Wang, Jin Zhu, Ning Yan and Jing Chen.

You can find the article here.

Abstract

Superhydrophobic polyurethane foam is one of the most promising materials for oil-water separation. However, there are only limited studies prepared matrix superhydrophobic foams as adsorbents. In this paper, SiO2 modified by 1H, 1H, 2H, 2H-perfluorododecyl trichlorosilane (F-SiO2) was added into the lignin-based foam matrix by a one-step foaming technique. The average diameter of F-SiO2 was about 480 nm with an water contact angle (WCA) of 160.3°. The lignin-based polyurethane foam with F-SiO2 had a superhydrophobic water contact angle of 151.3°. There is no obvious change in contact angle after 100 cycles of compression or after cutting and abrasion. Scanning electron microscopy (SEM) analysis showed that F-SiO2 was distributed both on the surface and inside of the foam. The efficiency for oil-water separation reached 99 %. Under the light intensity of 1 kW/m2, the surface temperature of the lignin-based foam rose to 77.6 °C. In addition, the foam exhibited self-cleaning properties and degraded within 2 h in an alcoholic alkali solution. Thus, in this study, we developed a novel matrix superhydrophobic lignin-based polyurethane foam with an excellent promise to be used as oil water separation adsorbents in industrial wastewater treatment and oil spill clean-up processes.

New Article: Catalyst-free pH-responsive chitosan-based dynamic covalent framework materials

A new article out of Ning Yan’s lab has been published in Carbohydrate Polymers written by Mohammad H Mahaninia and Ning Yan.

Click here to obtain an e-print of the full article for free until January 5th 2023.

Abstract

This study reports a first example of chitosan-based dynamic covalent framework materials successfully prepared through one-pot/ultrasonic-assisted amidation reaction via either citric acid (CA) or trimesic acid (TMA) as the linker unit under moderate conditions. Chitosan-based framework materials with residual carboxylic acid functional groups were obtained by tripodal cross-linking reactions without the need of any catalyst. The obtained materials were capable of bond exchange via neighboring group participation (NGP) effect within their dynamic covalent networks. It was demonstrated that the chitosan-based framework materials could undergo a dynamic transamidation reaction to exhibit self-healing characteristics. The structural properties of the synthesized dynamic covalent framework materials were controlled by the type and composition of the tripodal cross-linkers. This study showcased a novel approach to synthesize biodegradable, self-healing, pH-responsive, and selective mixed-dye adsorbent materials using chitosan as the building block.

New Article: Starch Maleate/Epoxidized Soybean Oil/Polylactic Acid Films with Improved Ductility and Biodegradation Potential for Packaging Fatty Foods

A new article out of Ning Yan’s lab has been published in the ACS Sustainable Chemistry & Engineering Journal about new sustainable packaging for Fatty Foods written by Shrestha Roy Goswami, Sandeep Sudnakaran Nair, Xiao Zhang, Nicolas R. Tanguy, and Ning Yan.

Click here to obtain an e-print of the full article for free for the first 50 people within the next year.

Abstract

The commercial marketability of polylactic acid (PLA) food packaging films is limited by their poor ductility and biodegradation ability. To address these challenges, a high-DS amylose-rich corn starch maleate (SM)/epoxidized soybean oil (ESO)/PLA composite film was developed. The film demonstrated significant ductility improvement (elongation at break increased from ≈3.63 to 36.75% while the tensile toughness improved 15-fold compared to the neat PLA film) because of improved interfacial interactions and mobility of ESO-plasticized PLA chains. Furthermore, due to absence of voids, the SM/ESO/PLA film also outperformed the ESO/PLA film in terms of oxygen (23,140 cm3 μm m–2 day–1 Pa–1) and water vapor (0.03 × 10–5 g m–1 day–1 Pa–1) barrier performances. These characteristics, together with findings that the SM/ESO/PLA film could rapidly breakdown in saline water (2.92 wt % per day) and compost (the C/N ratio increased from 20.4 to 22.69), as well as absence of ESO migration in fatty food simulants, make the SM/ESO/PLA film a promising material for food packaging.

New Article: Recyclable, self-strengthening starch-based epoxy vitrimer facilitated by exchangeable disulfide bonds

A new article out of Ning Yan’s lab has been published in the Chemical Engineering Journal about a self-strengthening, recyclable, starch-based epoxy vitrimer written by Nicole Tratnik, Nicolas R. Tanguy, and Ning Yan.

Click here to view the full article for free until October 5th, 2022.

Abstract

Epoxy vitrimers have emerged as a new class of self-healing, recyclable, and reprocessable materials, offering new opportunities to traditional epoxy thermosets by improving life-span, while providing additional functionalities. Nevertheless, retaining 100 % of the original mechanical performances remains difficult for vitrimers after several reprocessing cycles due to progressive changes in the vitrimer networks during rearrangements. In this study, we designed a novel epoxy vitrimer with a higher renewable content compared to conventional epoxies by using renewable materials. The bio-based epoxy vitrimer was synthesized from epoxidized starch amylopectin together with diallyl disulfide, that is naturally found in garlic, and a thiol (pentaerythritol tetrakis(3-mercaptopropionate) (PETMP)). Diallyl disulfide and PETMP enabled the formation of a recyclable, and reprocesseable, vitrimer network. The epoxy vitrimer displayed unprecedented self-strengthening after 5 recycling cycles (tensile strength increased over 900 %) caused by the mechanically-induced homogeneization of the diallyl disulfide/thiol and the starch epoxy ghost granule phases during the recycling process, thereby increasing the vitrimer cross-linking density during reformation. Reprocessing the vitrimer 5-times improved the mechanical and thermal properties, raising glass transition temperature, Young’s modulus, and tensile strength from 7 °C to 25 °C, 2.98 MPa to 268 MPa, and 1.87 MPa to 18.47 MPa, respectively. Hence, capitalizing on mechanically-induced phase homegeneization during the vitrimer reprocessing, this work introduces a strategy for the design of self-strengthening bio-based and recyclable thermosets.

New Article: Natural lignocellulosic nanofibrils as tribonegative materials for self-powered wireless electronics

A new article out of Ning Yan’s lab has been published in Nano Energy about lignocellulosic nanofibrils used in triboelectric nanogenerators written by Nicolas R. Tanguy, Masud Rana, Asif A. Khan, Nicole Tratnik, Heyu Chen, Dayan Ban and Ning Yan.

Click here to view the full article for free until June 24, 2022.

Abstract

Triboelectric nanogenerators (TENGs) are promising energy harvesting devices for powering next generation wearable electronics. TENGs performance are largely determined by the triboelectric effect between the tribonegative and tribopositive layers. To date, fluorine-containing petroleum-based polymers, such as polytetrafluoroethylene (PTFE), remain the most popular choice as tribonegative layer due to their high tribonegativity against various materials during frictional contact. We report for the first time a natural wood-derived lignocellulosic nanofibrils (LCNF) tribolayer that could replace fluorine-containing petroleum-based polymers as a tribonegative material for TENGs. The high tribonegativity was due to the presence of natural lignin on the surface of LCNF and LCNF’s nanofibril morphology. The LCNF nanopaper-based TENGs produced significantly higher voltage (~160%) and current (~120%) than TENGs with PTFE as the tribonegative material when paired with various polymeric/metallic tribolayers. Furthermore, assembling LCNF nanopaper as the tribonegative layers into a cascade TENG generated an output sufficient for powering a wireless communication node, capable of sending a radio-frequency signal to a smartphone every 3 min. This study demonstrates the excellent promises of using LCNF to make high-performance and more environmentally friendly wireless self-powered electronics; and thus pinpoints a new approach for fabricating sustainable triboelectric nanogenerators using natural lignocellulosic materials instead of conventional fluorine-containing petroleum-based polymers as tribonegative layers.

New Article: Functionalized lignin nanoparticles for producing mechanically strong and tough flame-retardant polyurethane elastomers

A new article out of Ning Yan’s lab has been published in the International Journal of Biological Macromolecules about functionalized lignin nanoparticles written by Hetian, Fangeng Chen, Wenxiang Zhu and Ning Yan.

Click here to view the full article for free until June 16, 2022.

Abstract
There is a strong interest in developing environmentally friendly synthesis approaches for making polyurethane elastomers (PUE) with desirable mechanical performance and flame retardancy suitable for a variety of applications. Hence, in this study, a novel nano functionalized lignin nanoparticle (Nano-FL) containing nitrogen (N) and phosphorus (P) moieties was developed via mild grafting reactions combined with the ultrasound method. The Nano-FL incorporated in the PUE acted as both crosslinking agents and flame retardants. The novel Nano-FL showed good compatibility and dispersibility in the PUE matrix, thereby overcoming the weakening effect of adding traditional lignin flame retardants on the mechanical properties of the PUE materials. PUE/Nano-FL exhibited strong tensile properties. Compared with control neat PUE, with 10 wt% of Nano-FL addition, the PUE attained a limiting oxygen index as high as 29.8% and it also passed the UL-94 V-0 rating. Furthermore, Cone Calorimetry Test (CCT) showed that the addition of Nano-FL not only reduced the heat release rate and the total heat release but also decreased the total smoke production rate during combustion. The char residues of PUEs with Nano-FL showed a high oxidation resistance with dense and continuous structural morphologies. The combined barrier and quenching effects of the char layer provided excellent flame retardancy performance. The novel Nano-FL developed in this study showed excellent promises as green functional additives for enhancing mechanical, thermal and flame retardancy performance of a wide range of polymers.