Browsing by Author "Jin, Yongcan"

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Insulative Biobased Glaze from Wood Laminates Obtained by Self-Adhesion
(2023-09-20) Chen, Chuchu; Zhou, Tong; Wan, Zhangmin; Xu, Zhaoyang; Jin, Yongcan; Li, Dagang; Rojas, Orlando J.
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
The combination of optical transparency and mechanical strength is a highly desirable attribute of wood-based glazing materials. However, such properties are typically obtained by impregnation of the highly anisotropic wood with index-matching fossil-based polymers. In addition, the presence of hydrophilic cellulose leads to a limited water resistance. Herein, this work reports on an adhesive-free lamination that uses oxidation and densification to produce transparent all-biobased glazes. The latter are produced from multilayered structures, free of adhesives or filling polymers, simultaneously displaying high optical clarity and mechanical strength, in both dry and wet conditions. Specifically, high values of optical transmittance (≈85.4%), clarity (≈20% with low haze) at a thickness of ≈0.3 mm, and highly isotropic mechanical strength and water resistance (wet strength of ≈128.25 MPa) are obtained for insulative glazes exhibiting low thermal conductivity (0.27 W m−1 K−1, almost four times lower than glass). The proposed strategy results in materials that are systematically tested, with the leading effects of self-adhesion induced by oxidation rationalized by ab initio molecular dynamics simulation. Overall, this work demonstrates wood-derived materials as promising solutions for energy-efficient and sustainable glazing applications.
Interfacial activity and Pickering stabilization of kraft lignin particles obtained by solvent fractionation
(2023-05-07) Tian, Jing; Chen, Jingqian; Wang, Peipei; Guo, Jiaqi; Zhu, Wenyuan; Khan, Mohammad Rizwan; Jin, Yongcan; Song, Junlong; Rojas, Orlando J.
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
This study aims to overcome the challenges of high-value utilization of technical lignins that encounters chemical complexity, heterogeneity and broad molecular mass distribution. Kraft lignin was fractionated through a practical strategy involving sequential dissolution in solvents of different polarities (water, tetrahydrofuran, and water/tetrahydrofuran v/v = 3/7). Lignin self-assembled drawing on the anti-solvent method, generating particles of controllable surface energy. Considering the governing factors in multiphase stabilization, the morphology, wetting characteristics and chemical composition of the kraft lignin particles (KLPs) were examined as a means to achieve controllable Pickering stabilization of oil-in-water (O/W) emulsions. The most anionic and hydrophilic KLPs formed aggregated networks (∼185 nm), which acted as a surfactant-type emulsifier following reversible adsorption at the O/W interfaces. Notably, the particles of the least hydrophilicity (∼146 nm) displayed a characteristic hollow structure. Such particles adsorbed slowly and weakly at the O/W interface, forming a viscoelastic layer around the oil droplets. The smallest lignin particles (∼39 nm) presented an intermediate hydrophilic character. They were uniform in size and formed rigid interfacial layers on the oil droplets. Accordingly, the devised relationship between particle morphogenesis and O/W stabilization capacity enabled the customization of lignin (size and wetting characteristics), allowing broader utilization in multiphase systems.
Intermolecular self-assembly of dopamine-conjugated carboxymethylcellulose and carbon nanotubes toward supertough filaments and multifunctional wearables
(2021-07-15) Guo, Tianyu; Wan, Zhangmin; Li, Dagang; Song, Junlong; Rojas, Orlando J.; Jin, Yongcan
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
The utilization of smart textiles, mainly in the form of yarns and wovens, requires high structural toughness and flexibility. To this end, we introduce a strategy based on the intermolecular self-assembly of dopamine-conjugated carboxymethyl cellulose (DA-CMC) with carbon nanotubes (CNT). Upon coagulation in a nonsolvent, the DA-CMC/CNT suspensions readily form composite filaments by the effects of hydrogen bonding, H-pi, anion-pi, and pi-pi interactions, as demonstrated by molecular dynamic simulation. The DA-CMC/CNT filaments display super-toughness (~76.2 MJ m−3), extensibility (strain to failure of ~14.8% at 90% RH, twice that of dopamine-free analogous systems) and high electrical conductivity. Moreover, the composite filaments form conductive networks that effectively support bending, strain and compression in air or fluid media. As such, they are suitable for application in wearables devices designed for sensing and electrothermal heating. Our proposed, scalable synthesis of multifunctional filaments opens new opportunities given their electroactivity and suitability for human interfacing.
Mechanisms of Strain-Induced Interfacial Strengthening of Wet-Spun Filaments
(2022-04-13) Guo, Tianyu; Wan, Zhangmin; Yu, Yan; Chen, Hui; Wang, Zhifeng; Li, Dagang; Song, Junlong; Rojas, Orlando J.; Jin, Yongcan
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
We investigate the mechanism of binding of dopamine-conjugated carboxymethyl cellulose (DA-CMC) with carbon nanotubes (CNTs) and the strain-induced interfacial strengthening that takes place upon wet drawing and stretching filaments produced by wet-spinning. The filaments are known for their tensile strength (as high as 972 MPa and Young modulus of 84 GPa) and electrical conductivity (241 S cm-1). The role of axial orientation in the development of interfacial interactions and structural changes, enabling shear load bearing, is studied by molecular dynamics simulation, which further reveals the elasto-plasticity of the system. We propose that the reversible torsion of vicinal molecules and DA-CMC wrapping around CNTs are the main contributions to the interfacial strengthening of the filaments. Such effects play important roles in impacting the properties of filaments, including those related to electrothermal heating and sensing. Our findings contribute to a better understanding of high aspect nanoparticle assembly and alignment to achieve high-performance filaments.