As of January 18th, the article Lignocellulosic Nanofibrils as Multifunctional Component for High-Performance Packaging Applications has made the top ten list on the Social Science Research Network (SSRN) with 25 downloads in the last 60 days.
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.
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.
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.
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.
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.
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.
As of October 18th, the article Recyclable, Self-Strengthening Starch-Based Epoxy Vitrimer Facilitated by Exchangeable Disulfide Bonds from Garlic has made the top ten list on the Social Science Research Network (SSRN) with 31 downloads in the last 60 days.
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.
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.
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.
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.
Last week, Shrestha successfully defended her PhD thesis, “Ionic Liquid Mediated Synthesis of Starch Maleates and their Application in Biodegradable Polymer Composites”. Congratulations Shrestha, your hard work paid off!