A new article from Ning Yan’s lab has been published in Carbohydrate Polymers written by Nicole Tratnik, Nicolas R. Tanguy, Daniel J. Davidson, Ning Yan.

You can find the article here.

Abstract

Bio-based epoxy vitrimers are gaining attention as sustainable alternatives to traditional epoxies due to renewable starting materials and recyclability, enabling material circularity. Transesterification, a dynamic bond reaction mechanism in vitrimers, relies on ample hydroxy and esters groups in the polymer network to rearrange under moderate conditions. To reduce reliance on petroleum we investigated starch, a natural feedstock rich in hydroxy groups. Ester bond densities were adjusted with an ester containing crosslinker (pentaerythritol tetrakis(3-mercaptopropionate) (PETMP)) at various epoxy to crosslinker molar ratios (1:0.7, 1:1, 1:1.25 and 1:1.5) with TEMPO as the catalyst. The reformation efficiency of the vitrimer increased to 239 % from 31 % when the ratio changed from 1:1 to 1:1.5. Essential dynamic behavioral parameters (dynamic bond exchange activation energy (E_a(d)), Arrhenius prefactor (τ₀), and freezing transition temperature (T_v)) were analysed. Adding excess amount of crosslinker decreased the T_g, crosslink density, E_a(d) and T_v of the starch-based epoxy vitrimer. Adhesion tests on birch veneer found that a 1:1.5 ratio had the highest adhesion performance at 3.02 ±0.7 MPa with an adhesion recovery as high as 91 % averaging 61 +/− 23 %. These insights into density of dynamic bonds and active functional groups will contribute to developing new bio-based vitrimers with designed circularity.

A new article from Ning Yan’s lab has been published in ACS Applied Polymer Materials written by Xiaobo Xu, Minghui Cui, Mengqiu Quan, Yuqing Wang, Genzheng Sha, Jin Zhu, Ning Yan, and Jing Chen.

You can find the article here

Abstract

The use of renewable raw materials to construct environmentally friendly, nontoxic, nonisocyanate polymer materials has been gaining attention. Here, we prepared ferulic acid epoxy (FAE) by directly reacting the lignin derivative ferulic acid with epichlorohydrin. It was used as a precursor to construct five-membered cyclic carbonate (CC) and five-membered cyclic dithiocarbonate (DTC) with CO₂ and CS₂, respectively. These cyclic carbonates are then cured with different amines to produce nonisocyanate polyurethanes (NIPUs) and nonisocyanate polythiourethanes (NIPTUs) with excellent properties. Ferulic acid contains a rigid aromatic ring structure, so the prepared nonisocyanate polymer materials have excellent mechanical properties, and the maximum tensile strength can reach 34.2 MPa. We compared NIPUs and NIPTUs in terms of their chemical structure, cross-link density, mechanical properties, and processing for remodeling. In addition, Due to the autoxidation of pendant sulfhydryl groups, disulfide bonds are present in the network structure of NIPTUs in addition to thionourethane. This endows NIPTUs with higher cross-link density, lower relaxation activation energy (E_a), and lower remodeling temperature (<140 °C). After thermocompression remodeling, the tensile strength of NIPTUs significantly increased due to the enhanced thermally induced formation of disulfide bonds. This study evaluates the potential for the direct synthesis of biobased aromatic NIPUs and NIPTUs based on ferulic acid, providing a simple route for the preparation of nonisocyanate polyurethanes and polythiourethanes using cyclic carbonates.

A new article from Ning Yan’s lab has been published in Chemical Engineering Journal written by Kaiwen Chen, Xianfu Xiao, Cheng Hao, Fengze Sun, Haonan Zhang, Yujing Tan, Jianyi Zhu, Hui Peng, Tianyi Zhan, Jianxiong Lyu and Ning Yan.

You can find the article here

Abstract

The asymmetric wettability of Janus membranes shows promising prospects in the field of liquid transport and separation, and researchers are seeking environmentally friendly and cost-effective feedstock for fabricating these membranes. In this study, we developed two types of high-performance, flexible, and durable asymmetric Janus membranes from wood: Janus cross-section wood membrane (JCW) and Janus longitudinal-section wood membrane (JLW). Wood, being an anisotropic material stemming from its grain orientation, possesses a hierarchical porous structure that can be tailored for various practical applications. The JCW, characterized by its vertical wood channel structure and larger pore size, demonstrated superior unidirectional water transport and fog collection capabilities. Its water–oil separation efficiency reached 99.9%, with a filtration flux exceeded 3000 L/m²∙h. The JLW, featuring three-dimensional interconnected micro-nano channels and layered pathways, was particularly effective in separating oil–water emulsions. The separation efficiency of oil–water emulsions reached 99.91%, with filtration fluxes for water-in-oil and oil-in-water emulsions being as high as 500 and 700 L/m²∙h, respectively. These results underscored the potential of asymmetric wettability Janus membranes in the fields of liquid transport and separation, while also paving the way for the utilization of sustainable and eco-friendly feedstocks.