New Article:Enhancing performance of phosphorus containing vanillin-based epoxy resins by P-N non-covalently functionalized graphene oxide nanofillers

A new article out of Ning Yan’s lab has been published in Composites Part B: Engineering written by Pitchaimari Gnanasekar, Heyu Chen, Nicole Tratnik, Martin Feng and Ning Yan.

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Abstract

            In this study, non-covalently functionalized graphene oxide (FGO) containing phosphorus and nitrogen was synthesized using dibenzyl N,N’-diethyl phosphoramidite (DDP)via a single step process. Meanwhile, novel bio-based phosphorus containing vanillin epoxy resin (VPE) was made via a two-step process and used as a flame-retardant adhesive. Subsequently, FGO was dispersed in the epoxy resin matrix at different weight ratios as reinforcement for improving mechanical, thermal and flame-retardant properties of the resultant composite systems. Curing behavior of the VPE and FGO mixtures with 4,4’-diaminodiphenylsulfone (DDS) as the crosslinker was investigated using a Differential Scanning Calorimeter (DSC). Thermal and flame-retardant properties of the cured VPE/FGO nanocomposites were systematically investigated by Thermogravimetric Analysis (TGA), Gas Chromatography – Mass Spectrometry (GC-MS), Limited Oxygen Index (LOI), vertical burning test (UL-94), and cone calorimeter test. Results indicated that all VPE/FGO nanocomposites exhibited excellent thermal and flame-retardant properties. In particular, VPE with 9wt% of FGO achieved the highest LOI value (29.1%) and passed the V-0 rating in the UL-94 test. Furthermore, cone calorimetry test showed that flame retardancy performance of the VPE and VPE/FGO composites significantly improved compared to vanillin epoxy control resin without phosphorus. The gaseous and high boiling pyrolysis products of VPE cured by DDS were collected and characterized by GC/MS to reveal their formation mechanisms. The char layers of the cued VPE showed a high oxidation resistance with intumescent structures. The combined barrier and quenching effects of the char layer imparted VPE with excellent flame retardancy. This study illustrated a promising approach for synthesizing mechanically strong, thermally-stable and environmentally-friendly flame-retardant bio-based composite resins.

New Article: Lignin Cellulose Nanofibrils as an Electrochemically Functional Component for High‐Performance and Flexible Supercapacitor Electrodes

A new article out of Prof. Ning Yan’s lab in collaboration with Prof. Lian’s lab (Materials Engineering) has been published in Chemistry Europe’s ChemSusChem written by Dr. Nicolas Tanguy, Dr. Haoran Wu, Dr. Sandeep Niar, Prof. Keryn Lian and Prof. Ning Yan. This article explores using lignin cellulose nanofibrils in fabricating flexible supercapacitor electrodes for wearable electronics.The article was selected as Very Important Paper by the Editors of the journal, invited for an article in Chemistryviews.org, and for a Cover art as well. More to come!

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Abstract

The increasing demand for wearable electronics has driven the development of supercapacitor electrode materials toward enhanced energy density, while being mechanically strong, flexible, as well as environmentally friendly and low‐cost. Taking advantage of faradaic reaction of quinone groups in natural lignin that is covalently bound to the high‐strength cellulose nanofibrils, the fabrication of a novel class of mechanically strong and flexible thin film electrodes with high energy storage performance is reported. The electrodes were made by growing polyaniline (PANI) on flexible films composed of lignin‐containing cellulose nanofibrils (LCNF) and reduced graphene oxide (rGO) nanosheets at various loading levels. The highest specific capacitance was observed for the LCNF/rGO/PANI electrode with 20 wt% rGO nanosheets (475 F g−1 at 10 mV s−1 and 733 F g−1 at 1 mV s−1), which represented a 68 % improvement as compared to a similar electrode made without lignin. In addition, the LCNF/rGO(20)/PANI electrode demonstrated high rate performance and cycle life (87 % after 5000 cycles). These results indicated that LCNF functioned as an electrochemically active multifunctional component to impart the composite electrode with mechanical strength and flexibility and enhanced overall energy storage performance. LCNF/rGO(20)/PANI electrode was further integrated in a flexible supercapacitor device, revealing the excellent promise of LCNF for fabrication of advanced flexible electrodes with reduced cost and environmental footprint and enhanced mechanical and energy storage performances.

New Article: Biobased Epoxidized Starch Wood Adhesives: Effect of Amylopectin and Amylose Content on Adhesion Properties

A new article out of Ning Yan’s lab has been published in ACS Sustainable Chemistry and Engineering written by Nicole Tratnik, Pei-Yu Kuo, Nicolas R. Tanguy, Pitchaimari Gnanasekar, and Ning Yan.
In this article studies the effect on amylopectin and amylose content in corn starches on modification through epoxidization and adhesion properties to wood

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Abstract

Formaldehyde-free, water-resistant, and environmentally friendly wood adhesives were prepared from starches via a simple one-step epoxidation reaction followed by cross-linking using diethylenetriamine. This study focused on the effect of amylose/amylopectin ratio of starch (high amylose, low amylose, and amylopectin) on the epoxidation reaction and on the bonding performance of the prepared epoxidized starches. The epoxidation of starches altered the fluid behavior of the resins, from Newtonian for pristine epoxy to shear thinning, that corroborated the successful integration of starch chains as part of the epoxy resin. Epoxidized amylopectin had the highest viscosity, 114 Pa.s, and a high degree of substitution, 2.33 ± 0.10, among the starches that indicated that amylopectin is more favorable for the grafting of epoxy groups and for the integration of starch chains in epoxy resins compared to the starches with high amylose content. Bonding strengths were determined by lap shear tests on yellow birch specimens in dry, wet, and boiled conditions. High amylopectin epoxidized starch showed the highest lap shear bonding performance under wet conditions (5.50 ± 0.451 MPa). Under boiled conditions, all three epoxidized starches showed equally better performance than the unreacted starch-filled epoxy blends. This study provides fundamental insights into the effect of starch molecular structure on epoxidation reaction and adhesion properties and suggests a promising approach for developing strong formaldehyde-free sustainable biobased wood adhesives.

New Article: Facile synthesize of phosphorus containing sustainable bio molecular platform from vanillin for the production of mechanically strong and highly flame-retardant resins

A new article out of Ning Yan’s lab has been published in ACS Sustainable Chemistry and Engineering written by Pitchaimari Gnanasekar, Martin Feng and Ning Yan

In this article a novel vanillin-based building block was used for synthesizing flame-retardant bio-based epoxy and polyurethane resins.

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Facile Synthesis of a Phosphorus-Containing Sustainable Biomolecular Platform from Vanillin for the Production of Mechanically Strong and Highly Flame-Retardant Resins Pitchaimari Gnanasekar, Martin Feng, Ning Yan*
ACS Sustainable Chem. Eng. 2020, Publication Date: November 18, 2020

Abstract

A novel chemical architecture, vanillin based phosphorus containing flame-retardant building block (VP)  was successfully synthesized as a sustainable platform biomolecule to be converted into  fire-retardant epoxy (VPE) and polyurethane (VPU) resins for application as environmentally-friendly adhesives. Structural characterizations confirmed the successful functionalization through their molecular structures. A series of VPU and VPE blends were prepared that showed excellent dry and wet bonding strengths and superior self‐extinguishing fire‐retardancy. The highest bonding strength of VPE80 for dry, cold and hot water treatment were noted about 3.64, 3.62 and 3.35 MPa respectively and the best fire‐retardant properties with the maximum LOI value of 29.6% and the lowest heat release rate according to cone calorimetry tests, due to the strong synergistic interpenetrating networks formed between the epoxy and PU macromolecules. The GC-MS analysis of the char residues indicated that the mechanisms for fire-retardancy were a combination of the quenching effect from the phosphorus-containing free radicals and the diluting effect of the non-flammable gases in the gas phase, plus the formation of phosphorus-rich char layers in the condensed phase. This study showcased a highly promising approach to develop environmentally-friendly high-performance fire-retardant chemicals using non-toxic vanillin as the starting material.

New Article: Lignin as a Key Component in Lignin-Containing Cellulose Nanofibrils for Enhancing the Performance of Polymeric Diphenylmethane Diisocyanate Wood Adhesives

A new article out of Ning Yan’s lab has been published in ACS Sustainable Chemistry + Engineering written by Heyu Chen, Pitchaimari Gnanasekar, Sandeep S. Nair, Wenbiao Xu, Prashant Chauhan, and Professor Ning Yan

In this article, lignin-containing cellulose nanofibrils (LCNFs) were used in polymeric diphenylmethane diisocyanate (pMDI) wood adhesives as a functional compound to significantly reinforce bonding properties.

For the first 12 months of publication, 50 free e-prints are available for interested colleagues.

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Lignin as a Key Component in Lignin-Containing Cellulose Nanofibrils for Enhancing the Performance of Polymeric Diphenylmethane Diisocyanate Wood Adhesives Heyu Chen, Pitchaimari Gnanasekar, Sandeep S. Nair, Wenbiao Xu, Prashant Chauhan, and Ning Yan ACS Sustainable Chemistry & Engineering Article ASAP
DOI: 10.1021/acssuschemeng.0c05642

Recent article from Prof. Yan group accepted in Green Chemistry

In this article, Dr. Heyu Chen, Dr. Prashant Chauhan, and Prof. Ning Yan reported a novel strategy to effectively utilize the bark waste stream as a promising starting material to synthesize environmental-friendly polyurethanes without using hazardous isocyanate/phosgene. Full details can be found here as the Accepted Manuscript.

Barking” up the right tree: biorefinery from waste stream to cyclic carbonate with immobilization of CO2 for non-isocyanate polyurethanes, Green Chemistry, 2020, DOI: 10.1039/D0GC02285C.

Recent Papers

A new paper from the Yan lab has been published in ACS Sustainable Chemistry + Engineering titled From Wastes to Functions: A New Soybean Meal and Bark-Based Adhesive written by Jing Luo, Ying Zhou, Qiang Gao, Jianzhang Li, and Ning Yan

For the first 12 months of publication, 50 free e-prints are available for interested colleagues.

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