World Scientific Annual Review of Functional Materials
Ever-increasing performance and functions of electronic systems are pushing the requirements for ... more Ever-increasing performance and functions of electronic systems are pushing the requirements for heat dissipation of devices at an unprecedented pace. To package individual devices (especially those working in high-power mode), research and development of thermal interface materials (TIMs) have accelerated since the beginning of this century. Thermal conduction, mechanical performance, and electrical insulation are the general specifications of interest besides their durability and reliability in developing TIMs. Mechanical performance is crucial in reducing the thermal interface resistance (TIR) between TIM and its bridged surfaces, i.e., between the device and the heat sink. To fill the gaps formed by the hard surfaces for reducing the TIR, TIMs should be “soft” enough upon external pressures. Nevertheless, depending on practical applications, the selection of TIM might release some specifications to guarantee the others. This review summarizes the latest developments of TIMs, add...
Aqueous chitosan-based polymer solution formed thermogel upon injection to accelerate the recover... more Aqueous chitosan-based polymer solution formed thermogel upon injection to accelerate the recovery of oral mucosa-related ulcers with desired properties.
In this work, a facile strategy was developed for the formation of an autonomous chitosanbased se... more In this work, a facile strategy was developed for the formation of an autonomous chitosanbased self-healing hydrogel. This hydrogel was fabricated using in situ free radical polymerization of acrylic acid (AA) and acrylamide (AM) in the presence of chitosan in dilute acetic acid aqueous solution under mild conditions. The in situ formed hydrogel is mainly composed of chitosan graft copolymers (CS-g-P(AM-r-AA)) and a small amount of non-grafted copolymers (P(AM-r-AA)), which interact with each other through a combination of multiple non-covalent interactions, including the inter-chain electrostatic complexation between-[AA]-segments and positively charged amino groups of chitosan, the H-bonding between-[AM]-segments and the H-bonding between-[AM]-segments and chitosan backbone. Owing to the cooperation of these non-covalent interactions and the reversible nature of the non-covalent network structure, the obtained hydrogel exhibits rapid network recovery, high stretchability and efficient autonomous self-healing properties. The hydrogel can also dissolve completely in dilute acidic aqueous solution under mild conditions visibly reflecting the unique network feature of this self-healing hydrogel system.
Sustainable biopolymers, Poly(lactide) (PLA), has been intensely researched over the past decades... more Sustainable biopolymers, Poly(lactide) (PLA), has been intensely researched over the past decades, due to its excellent biodegradability, renewability, and sustainability. The boundless potential of this sustainable biopolymer could resolve the adverse negative impact caused by the petroleum-based polymers. However, the inherent drawback of PLA such as brittleness, low heat distortion temperature and slow recrystallization rate narrowed the broad applications in biomedical, automotive and structural. In this study, we successfully synthesized a PHB-based filler (PHB-di-rub) displaying synergetic functions of (1) effective nucleating and (2) extreme toughening of the PLA matrix at only 5% (1.5 wt% PHB content). Remarkably, the storage modulus improves by 15%; tensile elongation extends by 57-fold (300% strain) and toughness by 38-fold while maintaining its original strength and stiffness. Likewise, 10% of PHB-di-rub (3 wt% PHB content) has an even higher improvement with storage modulus improve by 32%, elongation by 128-fold (680% strain) and toughness by 84-fold, with a marginal change in strength and stiffness. NMR results confirmed the 'brick and mortar' structure of PHB-di-rub, where PHB act as the rigid core and the poly(lactide-cocaprolactone) (DLA-co-CL) random copolymer confer the flexibility. DSC, WAXD, and POM display the excellent nucleating ability of PHB-di-rub. SEM shows the morphology of elongated fibrils structure with strong matrix-filler interaction and homogenous filler dispersion. SAXS, WAXS and WAXD elucidate the extreme toughening mechanism to be a combination of rubber-induced crazing effect and highly orientated PLA matrix with PHB-dirub. The Herman's orientation function further quantify the extreme elongation (680%) owing to the perfect alignment. This highly biodegradable biocomposite with high strength and toughness show potential in replacing the current petroleum-based polymers, which open up to broader prospects in the biomedical, automotive and structural application.
and methanol (analytical grade) were used as received. Au nanorods (NR-40-700-100) were purchased... more and methanol (analytical grade) were used as received. Au nanorods (NR-40-700-100) were purchased from Nanoseedz Ltd. Copper specimen grids (200 mesh) with formvar/carbon support film (referred to as TEM grids in the text) were purchased from XinXing BaiRui (T10023). Characterization Transmission electron microscopy (TEM) images were collected on a high-resolution transmission electron microscope (Philips CM 300). X-ray diffraction data was collected on Panalytical X'pert Pro X-ray diffractometer. Ultraviolet-visible (UV-vis) spectra were collected on a Cary 100 spectrophotometer. The loading amount of the catalyst in nano-hybrids was calculated based on the data collected on an Agilent 7700x inductively coupled plasma mass spectrometer (ICP-MS). For ICP characterization, the Au-ZIF-8 nano-hybrids were dissolved in aqua regia solution. Then, the resulting solutions were diluted with additional water and purified by filtration for ICP characterization. The Brunauer−Emmett−Teller (BET) surface area was evaluated using N 2 adsorption data in the relative pressure (P/Po) range of 0.06−0.33 using a micromeritics ASAP 2020 system. 1 H nuclear magnetic resonance (NMR) spectra of reactant 4-nitrophenol and product 4-aminophenol were recorded at JEOL 300 MHz spectrometer and Bruker 300 MHz spectrometer, respectively. Synthesis of Au nanospheres Citrate-stabilized Au nanoparticles (Au NPs) with diameter of about 30 nm were synthesized using wet chemistry. Hydrogen tetrachloroaurate(III) (10 mg) was dissolved in 100 mL of water and then the
Inspired by the biomineralization of unicellular diatoms, a biomimetic approach based on template... more Inspired by the biomineralization of unicellular diatoms, a biomimetic approach based on template (pluronic F127 micelle cluster)-induced self-assembly of α-cyclodextrin is developed to create hierarchical porous graphitic carbon spheres via hydrothermal treatment followed by pyrolysis. The as-obtained carbon spheres combine the features required for high-power electrode materials in lithium ion batteries (LIBs), such as high degree of graphitization, large surface area with hierarchically distributed pore sizes as well as doping with heteroatoms, which synergistically contribute to their impressive electrochemical properties. When applied as anode for LIBs, the carbon spheres exhibit high reversible capacity (ca. 700 mA h g-1 at 50 mA g-1), good cycling stability and remarkably outstanding high-rate performance (ca. 600, 450 and 290 mA h g-1 obtained at a current density of 1, 10 and 30 A g-1 , respectively), which is among the best of present pure carbon materials for LIBs applications. The fabrication process is straightforward and cost-effective, providing a new methodology for the tailored design of carbon materials with enhanced power densities for energy storage applications.
The future of green electronics possessing great strength and toughness proves to be a promising ... more The future of green electronics possessing great strength and toughness proves to be a promising area of research in this technologically advanced society. This work develops the first fully bendable and malleable toughened polylactic acid (PLA) green composite by incorporating a multifunctional polyhydroxybutyrate rubber copolymer filler that acts as an effective nucleating agent to accelerate PLA crystallization and performs as a dynamic plasticizer to generate massive polymer chain movement. The resultant biocomposite exhibits a 24-fold and 15-fold increment in both elongation and toughness, respectively, while retaining its elastic modulus at >3 GPa. Mechanism studies show the toughening effect is due to an amalgamation of massive shear yielding, crazing, and nanocavitation in the highly dense PLA matrix. Uniquely distinguished from the typical flexible polymer that stretches and recovers, this biocomposite is the first report of PLA that can be "bend, twist, turn, and fold" at room temperature and exhibit excellent mechanical robustness even after a 180° bend, attributes to the highly interconnected polymer network of innumerable nanocavitation complemented with an extensively unified fibrillar bridge. This unique trait certainly opens up a new horizon to future sustainable green electronics development.
World Scientific Annual Review of Functional Materials
Ever-increasing performance and functions of electronic systems are pushing the requirements for ... more Ever-increasing performance and functions of electronic systems are pushing the requirements for heat dissipation of devices at an unprecedented pace. To package individual devices (especially those working in high-power mode), research and development of thermal interface materials (TIMs) have accelerated since the beginning of this century. Thermal conduction, mechanical performance, and electrical insulation are the general specifications of interest besides their durability and reliability in developing TIMs. Mechanical performance is crucial in reducing the thermal interface resistance (TIR) between TIM and its bridged surfaces, i.e., between the device and the heat sink. To fill the gaps formed by the hard surfaces for reducing the TIR, TIMs should be “soft” enough upon external pressures. Nevertheless, depending on practical applications, the selection of TIM might release some specifications to guarantee the others. This review summarizes the latest developments of TIMs, add...
Aqueous chitosan-based polymer solution formed thermogel upon injection to accelerate the recover... more Aqueous chitosan-based polymer solution formed thermogel upon injection to accelerate the recovery of oral mucosa-related ulcers with desired properties.
In this work, a facile strategy was developed for the formation of an autonomous chitosanbased se... more In this work, a facile strategy was developed for the formation of an autonomous chitosanbased self-healing hydrogel. This hydrogel was fabricated using in situ free radical polymerization of acrylic acid (AA) and acrylamide (AM) in the presence of chitosan in dilute acetic acid aqueous solution under mild conditions. The in situ formed hydrogel is mainly composed of chitosan graft copolymers (CS-g-P(AM-r-AA)) and a small amount of non-grafted copolymers (P(AM-r-AA)), which interact with each other through a combination of multiple non-covalent interactions, including the inter-chain electrostatic complexation between-[AA]-segments and positively charged amino groups of chitosan, the H-bonding between-[AM]-segments and the H-bonding between-[AM]-segments and chitosan backbone. Owing to the cooperation of these non-covalent interactions and the reversible nature of the non-covalent network structure, the obtained hydrogel exhibits rapid network recovery, high stretchability and efficient autonomous self-healing properties. The hydrogel can also dissolve completely in dilute acidic aqueous solution under mild conditions visibly reflecting the unique network feature of this self-healing hydrogel system.
Sustainable biopolymers, Poly(lactide) (PLA), has been intensely researched over the past decades... more Sustainable biopolymers, Poly(lactide) (PLA), has been intensely researched over the past decades, due to its excellent biodegradability, renewability, and sustainability. The boundless potential of this sustainable biopolymer could resolve the adverse negative impact caused by the petroleum-based polymers. However, the inherent drawback of PLA such as brittleness, low heat distortion temperature and slow recrystallization rate narrowed the broad applications in biomedical, automotive and structural. In this study, we successfully synthesized a PHB-based filler (PHB-di-rub) displaying synergetic functions of (1) effective nucleating and (2) extreme toughening of the PLA matrix at only 5% (1.5 wt% PHB content). Remarkably, the storage modulus improves by 15%; tensile elongation extends by 57-fold (300% strain) and toughness by 38-fold while maintaining its original strength and stiffness. Likewise, 10% of PHB-di-rub (3 wt% PHB content) has an even higher improvement with storage modulus improve by 32%, elongation by 128-fold (680% strain) and toughness by 84-fold, with a marginal change in strength and stiffness. NMR results confirmed the 'brick and mortar' structure of PHB-di-rub, where PHB act as the rigid core and the poly(lactide-cocaprolactone) (DLA-co-CL) random copolymer confer the flexibility. DSC, WAXD, and POM display the excellent nucleating ability of PHB-di-rub. SEM shows the morphology of elongated fibrils structure with strong matrix-filler interaction and homogenous filler dispersion. SAXS, WAXS and WAXD elucidate the extreme toughening mechanism to be a combination of rubber-induced crazing effect and highly orientated PLA matrix with PHB-dirub. The Herman's orientation function further quantify the extreme elongation (680%) owing to the perfect alignment. This highly biodegradable biocomposite with high strength and toughness show potential in replacing the current petroleum-based polymers, which open up to broader prospects in the biomedical, automotive and structural application.
and methanol (analytical grade) were used as received. Au nanorods (NR-40-700-100) were purchased... more and methanol (analytical grade) were used as received. Au nanorods (NR-40-700-100) were purchased from Nanoseedz Ltd. Copper specimen grids (200 mesh) with formvar/carbon support film (referred to as TEM grids in the text) were purchased from XinXing BaiRui (T10023). Characterization Transmission electron microscopy (TEM) images were collected on a high-resolution transmission electron microscope (Philips CM 300). X-ray diffraction data was collected on Panalytical X'pert Pro X-ray diffractometer. Ultraviolet-visible (UV-vis) spectra were collected on a Cary 100 spectrophotometer. The loading amount of the catalyst in nano-hybrids was calculated based on the data collected on an Agilent 7700x inductively coupled plasma mass spectrometer (ICP-MS). For ICP characterization, the Au-ZIF-8 nano-hybrids were dissolved in aqua regia solution. Then, the resulting solutions were diluted with additional water and purified by filtration for ICP characterization. The Brunauer−Emmett−Teller (BET) surface area was evaluated using N 2 adsorption data in the relative pressure (P/Po) range of 0.06−0.33 using a micromeritics ASAP 2020 system. 1 H nuclear magnetic resonance (NMR) spectra of reactant 4-nitrophenol and product 4-aminophenol were recorded at JEOL 300 MHz spectrometer and Bruker 300 MHz spectrometer, respectively. Synthesis of Au nanospheres Citrate-stabilized Au nanoparticles (Au NPs) with diameter of about 30 nm were synthesized using wet chemistry. Hydrogen tetrachloroaurate(III) (10 mg) was dissolved in 100 mL of water and then the
Inspired by the biomineralization of unicellular diatoms, a biomimetic approach based on template... more Inspired by the biomineralization of unicellular diatoms, a biomimetic approach based on template (pluronic F127 micelle cluster)-induced self-assembly of α-cyclodextrin is developed to create hierarchical porous graphitic carbon spheres via hydrothermal treatment followed by pyrolysis. The as-obtained carbon spheres combine the features required for high-power electrode materials in lithium ion batteries (LIBs), such as high degree of graphitization, large surface area with hierarchically distributed pore sizes as well as doping with heteroatoms, which synergistically contribute to their impressive electrochemical properties. When applied as anode for LIBs, the carbon spheres exhibit high reversible capacity (ca. 700 mA h g-1 at 50 mA g-1), good cycling stability and remarkably outstanding high-rate performance (ca. 600, 450 and 290 mA h g-1 obtained at a current density of 1, 10 and 30 A g-1 , respectively), which is among the best of present pure carbon materials for LIBs applications. The fabrication process is straightforward and cost-effective, providing a new methodology for the tailored design of carbon materials with enhanced power densities for energy storage applications.
The future of green electronics possessing great strength and toughness proves to be a promising ... more The future of green electronics possessing great strength and toughness proves to be a promising area of research in this technologically advanced society. This work develops the first fully bendable and malleable toughened polylactic acid (PLA) green composite by incorporating a multifunctional polyhydroxybutyrate rubber copolymer filler that acts as an effective nucleating agent to accelerate PLA crystallization and performs as a dynamic plasticizer to generate massive polymer chain movement. The resultant biocomposite exhibits a 24-fold and 15-fold increment in both elongation and toughness, respectively, while retaining its elastic modulus at >3 GPa. Mechanism studies show the toughening effect is due to an amalgamation of massive shear yielding, crazing, and nanocavitation in the highly dense PLA matrix. Uniquely distinguished from the typical flexible polymer that stretches and recovers, this biocomposite is the first report of PLA that can be "bend, twist, turn, and fold" at room temperature and exhibit excellent mechanical robustness even after a 180° bend, attributes to the highly interconnected polymer network of innumerable nanocavitation complemented with an extensively unified fibrillar bridge. This unique trait certainly opens up a new horizon to future sustainable green electronics development.
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