Enriching Heteroelements in Lignin as Lubricating Additives for Bioionic Liquids

Mu, Liwen; Shi, Yijun; Guo, Xiao-Jing; Wu, Jian; Ji, Tuo; Chen, Long; Feng, Xin; Lü, Xiaohua; Hua, Jing; Zhu, Jiahua

doi:10.1021/acssuschemeng.6b00669

Cited by 37 publications

(19 citation statements)

References 64 publications

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“…Polymer blending is an effective way to increase the density of H-bonds because one component polymer can supply donating group while the other to supply accepting groups. Biopolymers in which the H-bond molecular group exist widely are usually applied in polymer blends, such as gelatin which possesses abundant carboxylic, amide, and amine groups, [46][47][48] lignin which owns abundant hydroxyl and aldehyde groups [49,50]. The H-bond density and the mixture ratio of polymer blends could strongly affect the thermal conductivity.…”

Section: Hydrogen Bondmentioning

confidence: 99%

Thermal conductivity of polymers and polymer nanocomposites

Huang

Qian

Yang

2018

Materials Science and Engineering: R: Reports

670

391

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Polymers are widely used in industry and in our daily life because of their diverse functionality, light weight, low cost and excellent chemical stability. However, on some applications such as heat exchangers and electronic packaging, the low thermal conductivity of polymers is one of the major technological barriers. Enhancing the thermal conductivity of polymers is important for these applications and has become a very active research topic over the past two decades. In this review article, we aim to: 1). systematically summarize the molecular level understanding on the thermal transport mechanisms in polymers in terms of polymer morphology, chain structure and inter-chain coupling; 2). highlight the rationales in the recent efforts in enhancing the thermal conductivity of nanostructured polymers and polymer nanocomposites. Finally, we outline the main advances, challenges and outlooks for highly thermal-conductive polymer and polymer nanocomposites. the inter-chain coupling. Fig. 1 Schematic diagrams of a polymer: (a) the morphology of a polymer consisting of crystalline and amorphous domains; (b) structure of a polymer chain.In addition to engineering the morphology of polymer chains, another common method to enhance the thermal conductivity of polymers is to blend polymers with highly thermal conductive fillers. The progress of nanotechnology over the last two decades not only provides more diverse high thermal conductivity fillers of different material types and topological shapes but also advances the understanding at the nanoscale. Fig. 2 shows a sketch of a polymer nanocomposite to illustrate the thermal transport mechanisms. In general, there are two types of polymer nanocomposites depending on whether nano-fillers form a network or not. When the filler concentration is low, no inter-filler networks could be formed, as shown in Fig. 2(a). The thermal conductivity is essentially determined by the filler-matrix coupling, i.e, interfacial thermal resistance, and the concentration and the geometric shapes of fillers. When the filler concentration is large enough, high conductivity fillers might form thermally conductive networks, as shown in Fig. 2(b). Although nanocomposites with filler network could possess a higher thermal conductivity than that without a network, their thermal conductivity could still be low due to the large inter-filler thermal contact resistance. Recently, three-dimensional fillers, such as carbon and graphene foams, have drawn a lot of attention. The fundamental thermal transport mechanisms and recent synthesis efforts in both types of nanocomposites are reviewed.This review article is organized as follows. In Section 2, we introduce the experimental progress on the enhancement of thermal conductivity by aligning polymer chains, and then review the methods to further tune the thermal conductivity by engineering chain structure and inter-chain coupling, as illustrated in Fig. 3(a). In Section 3, we discuss the thermal conductivity of polymer nanocomposites both with and without inter...

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Section: Hydrogen Bondmentioning

confidence: 99%

Thermal conductivity of polymers and polymer nanocomposites

Huang

Qian

Yang

2018

Materials Science and Engineering: R: Reports

670

391

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“…Both rGO and PEG contain polar groups which provide effective dispersion stability through hydrogen bonding. Moreover, PEG is widely used in biomedical applications for reducing the friction and wear of knee joints1819, but the use of rGO as blend additive to PEG for biomedical applications needs to be thoroughly investigated in term of safety7. The interaction mechanism of hydroxyl-hydroxyl and epoxy-hydroxyl terminated rGO with PEG were investigated.…”

mentioning

confidence: 99%

Role of oxygen functional groups in reduced graphene oxide for lubrication

Gupta

Kumar

Panda

et al. 2017

Sci Rep

498

195

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Functionalized and fully characterized graphene-based lubricant additives are potential 2D materials for energy-efficient tribological applications in machine elements, especially at macroscopic contacts. Two different reduced graphene oxide (rGO) derivatives, terminated by hydroxyl and epoxy-hydroxyl groups, were prepared and blended with two different molecular weights of polyethylene glycol (PEG) for tribological investigation. Epoxy-hydroxyl-terminated rGO dispersed in PEG showed significantly smaller values of the friction coefficient. In this condition, PEG chains intercalate between the functionalized graphene sheets, and shear can take place between the PEG and rGO sheets. However, the friction coefficient was unaffected when hydroxyl-terminated rGO was coupled with PEG. This can be explained by the strong coupling between graphene sheets through hydroxyl units, causing the interaction of PEG with the rGO to be non- effective for lubrication. On the other hand, antiwear properties of hydroxyl-terminated rGO were significantly enhanced compared to epoxy-hydroxyl functionalized rGO due to the integrity of graphene sheet clusters.

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“…The overall philosophy herein is to assist deconstruction of lignocellulosic material via covalent modifications, thus generating functional secondary building blocks. For instance, Zhu et al 90 reported on the phosphorylation of kraft lignin for the preparation of new lubricant additives. As shown in Scheme 11 , the authors exploited hydrogen chloride, which is generated in situ during the synthesis of (imidazol-1-yl)phosphonic dichloride, to hydrolyze ether bonds (typically β- O -4 bonds; Scheme 9 ).…”

Section: From Raw To Functionalized Ligninmentioning

confidence: 99%

“…Besides the incorporation of new functionalities and the decrease in molecular weight, the solubility of such functional lignin in polar solvents could be significantly improved. 90 …”

Section: From Raw To Functionalized Ligninmentioning

confidence: 99%