Electrically conductive elastomer composites(CECs)with segregated networks of conductive nanofillers show high potential in stretchable strain sensors due to balanced mechanical and electrical properties,yet the sensi...Electrically conductive elastomer composites(CECs)with segregated networks of conductive nanofillers show high potential in stretchable strain sensors due to balanced mechanical and electrical properties,yet the sensitivity at low strain is generally insufficient for practical application.Herein,we report an easy and effective way to improve the resistive response to low strain for CECs with segregated network structure via adding stiff alumina into carbon nanostructures(CNS).The CEC containing 0.7 wt%CNS and 5 wt%Al_(2)O_(3) almost sustains the same elasticity(elongation at break of~900%)and conductivity(0.8 S/m)as the control,while the piezoresistive sensitivity is significantly improved.Thermoplastic polyurethane(TPU)composites with a segregated network of hybrid nanofillers(CNS and Al_(2)O_(3))show much higher strain sensitivity(Gauge factor,GF-566)at low strain(45%strain)due to a local stress concentration effect,this sensitivity is superior to that of TPU/CNS composites(GF-11).Such a local stress concentration effect depends on alumina content and its distribution at the TPU particle interface.In addition,CECs with hybrid fillers show better reproducibility in cyclic piezoresistive behavior testing than the control.This work offers an easy method for fabricating CECs with a segregated filler network offering stretchable strain sensors with a high strain sensitivity.展开更多
The development of a durable metallic coating on diverse substrates is both intriguing and challenging,particularly in the research of metal-conductive materials for applications such as batteries,soft electronics,and...The development of a durable metallic coating on diverse substrates is both intriguing and challenging,particularly in the research of metal-conductive materials for applications such as batteries,soft electronics,and beyond.Herein,by learning from the pencil-writing process,a facile solid-ink rubbing technology(SIR-tech)is invented to address the above challenge.The solid-ink is exampled by rational combination of liquid metal and graphite particles.By harnessing the synergistic effects between rubbing and adhesion,controllable metallic skin is successfully formed onto metals,woods,ceramics,and plastics without limitation in size and shape.Moreover,outperforming pure liquid-metal coating,the composite metallic skin by SIR-tech is very robust due to the self-lamination of graphite nanoplate exfoliated by liquid-metal rubbing.The critical factors controlling the structures-properties of the composite metallic skin have been systematically investigated as well.For applications,the SIR-tech is demonstrated to fabricate high-performance composite current collectors for next-generation batteries without traditional metal foils.Meanwhile,advanced skin-electrodes are further demonstrated for stable triboelectricity generation even under temperature fluctuation from-196 to 120℃.This facile and highly-flexible SIR-tech may work as a powerful platform for the studies on functional coatings by liquid metals and beyond.展开更多
Pre-polymerized vinyl trimethoxy silane(PVTMS)@MWCNT nano-aerogel system was constructed via radical polymerization,sol-gel transition and supercritical CO_(2)drying.The fabricated organic-inorganic hybrid PVTMS@MWCNT...Pre-polymerized vinyl trimethoxy silane(PVTMS)@MWCNT nano-aerogel system was constructed via radical polymerization,sol-gel transition and supercritical CO_(2)drying.The fabricated organic-inorganic hybrid PVTMS@MWCNT aerogel structure shows nano-pore size(30-40 nm),high specific surface area(559 m^(2)g^(−1)),high void fraction(91.7%)and enhanced mechanical property:(1)the nano-pore size is beneficial for efficiently blocking thermal conduction and thermal convection via Knudsen effect(beneficial for infrared(IR)stealth);(2)the heterogeneous interface was beneficial for IR reflection(beneficial for IR stealth)and MWCNT polarization loss(beneficial for electromagnetic wave(EMW)attenuation);(3)the high void fraction was beneficial for enhancing thermal insulation(beneficial for IR stealth)and EMW impedance match(beneficial for EMW attenuation).Guided by the above theoretical design strategy,PVTMS@MWCNT nano-aerogel shows superior EMW absorption property(cover all Ku-band)and thermal IR stealth property(ΔT reached 60.7℃).Followed by a facial combination of the above nano-aerogel with graphene film of high electrical conductivity,an extremely high electromagnetic interference shielding material(66.5 dB,2.06 mm thickness)with superior absorption performance of an average absorption-to-reflection(A/R)coefficient ratio of 25.4 and a low reflection bandwidth of 4.1 GHz(A/R ratio more than 10)was experimentally obtained in this work.展开更多
Poly(decamethylene terephthalamide/decamethylene isophthalamide)-block-polyvinyl alcoho)(PA10 T/10 IPEG) copolymer/graphene oxide(GO) composites were prepared via in-situ melt polymerization and two different nano-fil...Poly(decamethylene terephthalamide/decamethylene isophthalamide)-block-polyvinyl alcoho)(PA10 T/10 IPEG) copolymer/graphene oxide(GO) composites were prepared via in-situ melt polymerization and two different nano-filler addition approaches were compared. The relationship between the micro-structure and performance of the elastomer composites prepared by one-step and two-step methods was explored. The results show that the two-step method significantly promoted the dispersion of the GO in a polymer matrix, and facilitated the grafting of more hard molecular chains. Thus, the elastic modulus and tensile strength of the nanocomposite have been significantly improved by the presence of GO. This was because of the strong interaction between the functional groups on the surface of the GO and the hard molecular chains. This would be also be favorable to load transfer across the interface. Additionally, the elongation at the break of composites increased by 10% with the addition of a small amount of GO(0.2% wt). This is because hard domains tend to be enriched on the surface of GO in composites and act as a lubricating layer at the interface between the GO and matrix, leading to increased deformation ability. This work provides an effective strategy to prepare elastomer composites with high strength and toughness.展开更多
A novel phthalonitrile derivative containing an amino group, 3,5-bis(3,4-dicyanophenoxy)aniline (CPA), was synthesized via a nucleophilic displacement of 4-nitrophthalonitrile and 5-aminoresorcinol hydrochloride. The ...A novel phthalonitrile derivative containing an amino group, 3,5-bis(3,4-dicyanophenoxy)aniline (CPA), was synthesized via a nucleophilic displacement of 4-nitrophthalonitrile and 5-aminoresorcinol hydrochloride. The structure of CPA was confirmed by Fourier transform infrared spectra (FT-IR) and nuclear magnetic resonance (1H NMR). Thermal analysis performed on CPA revealed that the novel phthalonitrile derivative showed a self-promotion curing behavior and the resulting polymer exhibited outstanding heat-resistance.展开更多
The rheological behavior, thermal properties and foam morphology of linear polypropylene and long chain branching polypropylene prepared through UV irradiation reactive extrusion were studied by rheological test, melt...The rheological behavior, thermal properties and foam morphology of linear polypropylene and long chain branching polypropylene prepared through UV irradiation reactive extrusion were studied by rheological test, melt index test, DSC and supercritical carbon dioxide foaming technology. Rheological test and melt index test confirmed that under UV irradiation and extrusion, adding photo-initiator and cross-linking agent could achieve the purpose of branching, thus improved the melt strength of polypropylene effectively. The DSC results revealed that with the introducing of long chain branching, the melting range of the polypropylene broadened and the crystallization temperature increased. Owing to the introduction of long chain branches, polypropylene exhibited higher melt strength and strain hardening behavior. Compared with linear polypropylene, the foam morphologies of long chain branching polypropylene were more uniform.展开更多
Of all the existing materials, plastics are no doubt among the most versatile ones. However, the extreme increases in plastic production as well as the difficulty of the material for degradation have led to a huge num...Of all the existing materials, plastics are no doubt among the most versatile ones. However, the extreme increases in plastic production as well as the difficulty of the material for degradation have led to a huge number of plastic wastes. Their recycling rate after disposal is less than 10%, resulting in a series of serious environmental and ecological problems as well as a significant waste of resources. Current recycling methods generally suffer from large energy consumption, the low utilization rate of recycled products with low added value, and produce other waste during the process. Here, we summarized recentlydeveloped chemical recycling ways on commodity plastics, especially new catalytic paths in production of fuels, high-valued chemicals and advanced materials from a single virgin or a mixture of plastic waste,which have emerged as promising ways to valorize waste plastics more economically and environmentally friendly. The new catalyst design criteria as well as innovative catalytic paths and technologies for plastic upcycling are highlighted. Beyond energy recovery by incineration, these approaches demonstrate how waste plastics can be a viable feedstock for energy use with the generation of clean H_(2), high-quality liquid fuels and materials for energy storage, and help inspiring more catalytic process on plastic upcycling to overcome the economical hurdle and building a circular plastic economy.展开更多
Biodegradable composite films based on chitosan and lignin with various composition were prepared via the solution-casting technique.FT-IR results indicate the existence of hydrogen bonding between chitosan and lignin...Biodegradable composite films based on chitosan and lignin with various composition were prepared via the solution-casting technique.FT-IR results indicate the existence of hydrogen bonding between chitosan and lignin,and SEM images show that lignin could be well dispersed in chitosan when the content of lignin is below 20 wt%due to the strong interfacial interaction.As a result of strong interaction and good dispersion,the tensile strength,storage modulus,thermal degradation temperature and glass transi...展开更多
The present work enhanced the thermal conductivity of poly(p-phenylene sulfi de)/expanded graphites and poly(p-phenylene sulfi de)/carbon nanotubes, by incorporating composites with hexagonal boron nitride, which simu...The present work enhanced the thermal conductivity of poly(p-phenylene sulfi de)/expanded graphites and poly(p-phenylene sulfi de)/carbon nanotubes, by incorporating composites with hexagonal boron nitride, which simultaneously succeeded in raising the electrical conductivity of the systems. A two-step mechanical processing method which includes rotating solid-state premixing and inner mixing was adopted to improve dispersion of the hybrids, contributing to the formation of an interspered thermal conductive network. Similar synergic effect in thermal conductivity enhancement was discovered in the hybrid systems regardless of the dimension difference between the two carbon fi llers. Such is postulated to be the one satisfying advantage generated by the afore-mentioned network; the other is the insulativity of the hybrid systems given by the effective blockage of hexagonal boron nitride as an insulating material in our network.展开更多
The non-isothermal crystallization of poly(L-lactide)(PLLA) under quiescent and steady shear flow conditions was in situ investigated by using polarizing optical microscopy(POM) with a hot shear stage and wide-angle X...The non-isothermal crystallization of poly(L-lactide)(PLLA) under quiescent and steady shear flow conditions was in situ investigated by using polarizing optical microscopy(POM) with a hot shear stage and wide-angle X-ray diffraction(WAXD).The shear rate and the cooling rate both play a significant role in the final crystalline morphology and crystallinity.Under quiescent conditions,the morphology assumes different sized spherulites,and its crystallinity dramatically reduces with increasing the cooling rate.On the other hand,the shear flow increases the onset crystallization temperature,and enhances the final crystallinity.When the shear rate is above 5 s^(-1),cylindrite-like crystals are observed, furthermore,their content depends on the cooling rate.展开更多
The effects of postthermal treatment and irradiation time on the structure and thermal stability of TiO2/polyacrylate nano- composites by a sol-gel process in reverse micelles and subsequent rapid photopolymerization ...The effects of postthermal treatment and irradiation time on the structure and thermal stability of TiO2/polyacrylate nano- composites by a sol-gel process in reverse micelles and subsequent rapid photopolymerization were investigated, and the hybrid films were characterized by thermal gravimetry analysis (TGA), X-ray photoelectron spectrum (XPS), and atomic force microscopy (AFM). XPS data suggested that the prolongation of irradiation time and the postthermal treatment promoted titania formation, with the former affecting more remarkably. TGA data showed that TiO2-hybrid films could upgrade the decomposition onset temperature (Tonset) as well as the temperature at which there is a maximum mass loss rate (Tmax). AFM data demonstrated that the inorganic titania particles with a mean diameter of 25.26-28.84 nm were homogeneously distributed in the organic matrix.展开更多
A diamine monomer 4,4′-methylenedianiline(MDA) was introduced to modify the polyimide of pyromellitic dianhydride(PMDA) and 4,4′-oxydianiline(ODA) by polycondensation. A series of polyamic acids was synthesized from...A diamine monomer 4,4′-methylenedianiline(MDA) was introduced to modify the polyimide of pyromellitic dianhydride(PMDA) and 4,4′-oxydianiline(ODA) by polycondensation. A series of polyamic acids was synthesized from MDA and ODA of different molar ratios with PMDA of sum mole of moles of MDA and ODA, and polyimide films were obtained by thermal imidization. Polyimide(PI) films were characterized by tensile testing, dynamic mechanical analysis(DMA), thermal gravimetry analysis(TGA), Fourier transform infrared spectroscopy (FTIR), wide X-ray diffraction(WAXD) and molecular simulation. With the increase of MDA content, the tensile strength and thermal decomposition temperature remained generally stable compared with those of PMDA/ODA polyimide. Unexpectedly, the glass transition temperature(Tg) and Young's modulus increased from 388.7 °C and 2.37 GPa to 408.3 °C and 5.74 GPa, respectively. The results of WAXD and molecular simulation indicate the steric hindrance among hydrogen atoms of the linkage groups and adjacent phenyls enhanced the properties of the polyimide modified with MDA.展开更多
Functional polymer composites(FPCs)have attracted increasing attention in recent decades due to their great potential in delivering a wide range of functionalities.These functionalities are largely determined by funct...Functional polymer composites(FPCs)have attracted increasing attention in recent decades due to their great potential in delivering a wide range of functionalities.These functionalities are largely determined by functional fillers and their network morphology in polymer matrix.In recent years,a large number of studies on morphology control and interfacial modification have been reported,where numerous preparation methods and exciting performance of FPCs have been reported.Despite the fact that these FPCs have many similarities because they are all consisting of functional inorganic fillers and polymer matrices,review on the overall progress of FPCs is still missing,and especially the overall processing strategy for these composites is urgently needed.Herein,a"Toolbox"for the processing of FPCs is proposed to summarize and analyze the overall processing strategies and corresponding morphology evolution for FPCs.From this perspective,the morphological control methods already utilized for various FPCs are systematically reviewed,so that guidelines or even predictions on the processing strategies of various FPCs as well as multi-functional polymer composites could be given.This review should be able to provide interesting insights for the field of FPCs and boost future intelligent design of various FPCs.展开更多
In order to resolve the increasing resistance phenomena of the Gram-negative bacteria against single chain quaternary ammonium salts (QAS), lysine with a pedant fluorinated bis-ammonium salts was synthesized and its a...In order to resolve the increasing resistance phenomena of the Gram-negative bacteria against single chain quaternary ammonium salts (QAS), lysine with a pedant fluorinated bis-ammonium salts was synthesized and its antimicrobial properties were evaluated in this work. The novel fluorinated bis-ammonium salts shows similar activity with conventional single chain quaternary ammonium salts against Gram-positive bacteria but stronger activity against Gram-negative bacteria and yeast compared with the single chained counterpart.展开更多
Poly(arylene sulfide sulfone)/graphene nanoplate(PASS/GNP) composites with segregated structure based on continuous polymer fiber skeletons were fabricated by coating a thin conductive layer on the PASS fibers and the...Poly(arylene sulfide sulfone)/graphene nanoplate(PASS/GNP) composites with segregated structure based on continuous polymer fiber skeletons were fabricated by coating a thin conductive layer on the PASS fibers and then performing compression molding. The formation of a unique segregated conductive network endowed the PASS/GNP composites with high electrical conductivity and excellent electromagnetic interference(EMI) shielding effectiveness(SE), reaching 17.8 S/m and 30.1 d B, respectively, when the content of the GNPs in the conductive layer was 20 wt%. The PASS/GNP composites also exhibited outstanding mechanical properties, which was attributed to the continuous PASS fiber skeletons that could withstand large loads and the strong interfacial interaction between the conductive layers and the PASS fibers that could provide good stress transfer. This approach is suitable for most soluble polymers.展开更多
It has been well known that fluorinated polyurethanes exhibit uniquely low surface energy, biocompatibility and biostability, thermal and oxidative stability and nonsticking behavior. Consequently, these polymers have...It has been well known that fluorinated polyurethanes exhibit uniquely low surface energy, biocompatibility and biostability, thermal and oxidative stability and nonsticking behavior. Consequently, these polymers have attracted considerable interest. However, the mechanical properties of fluorinated polyurethanes usually decline with increasing fluorine contents. The blending of fluorinated polyurethanes with normal polyurethane was carried out to achieve balanced mechanical and surface properties. It was found that polyurethane with good mechanical properties and low surface energy can be obtained by adding a small amount of fluorinated polyurethane. The fluorinated side chains can easily migrate to uppermost surfaces of the blends untill the fluorine level at the surface becomes almost saturated. It has been shown from contact angle, XPS and AFM measurements that only as little as 0.34 wt% of fluorine level is enough to produce a surface saturated with fluorine, and the fluorine level at the uppermost surface is one hundred times higher than that in the blend bulk. The final outer surface structures of the polyurethane blend were independent of the content of the fluorinated polyurethane in the blends due to the surfaces saturated by fluorine.展开更多
Cutting-edge heat spreaders for soft and planar electronics require not only high thermal conductivity and a certain degree of flexibility but also remarkable self-adhesion without thermal interface materials, elastic...Cutting-edge heat spreaders for soft and planar electronics require not only high thermal conductivity and a certain degree of flexibility but also remarkable self-adhesion without thermal interface materials, elasticity, arbitrary elongation along with soft devices, and smart properties involving thermal self-healing, thermochromism and so on. Nacre-like composites with excellent in-plane heat dissipation are ideal as heat spreaders for thin and planar electronics. However, the intrinsically poor viscoelasticity, i.e., adhesion and elasticity, prevents them from simultaneous self-adhesion and arbitrary elongation along with current flexible devices as well as incurring high interfacial thermal impedance. In this paper, we propose a soft thermochromic composite(STC) membrane with a layered structure, considerable stretchability, high in-plane thermal conductivity(~30 Wm^(-1) K^(-1)), low thermal contact resistance(~12 mm^2 KW^(-1), 4–5 times lower than that of silver paste), strong yet sustainable adhesion forces(~4607 Jm^(-2), 2220 Jm^(-2) greater than that of epoxy paste) and self-healing efficiency. As a self-adhesive heat spreader, it implements efficient cooling of various soft electronics with a temperature drop of 20℃ than the polyimide case. In addition to its self-healing function, the chameleon-like behavior of STC facilitates temperature monitoring by the naked eye, hence enabling smart thermal management.展开更多
A novel biphenyl side-chained diamine with alkyloxy spacer and alkyloxy tail,4'-butoxy-4-(3,5-diaminobenzoyloxy)hexyloxybiphenyl(C6BBC4),was synthesized and characterized by FTIR and 1 H NMR.A series of polyimide(...A novel biphenyl side-chained diamine with alkyloxy spacer and alkyloxy tail,4'-butoxy-4-(3,5-diaminobenzoyloxy)hexyloxybiphenyl(C6BBC4),was synthesized and characterized by FTIR and 1 H NMR.A series of polyimide(PI) films with different side chain contents was synthesized from biphenyltetracarboxylicdianhydride(BPDA),4,4'-oxydianiline(ODA) and C6BBC4,and their thermal properties,optical transparency and liquid crystal alignment property,and so on,were investigated by thermogravimetric analysis(TGA),differential scanning calorimetry(DSC),crystal rotation method,polarizing microscopy and UV-Vis spectra.With the content of side chained diamine increasing from 0 to 100%,the η inh of poly(amide acid)(PAA) decreased rapidly from 3.0 to 0.51,the glass transition temperature(T g) of polyimides(PIs) decreased from 274 ℃ to 203 ℃ and the Vis-light transmittance of alignment films substantially increased.As for the alignment properties,the pretilt angle of PI alignment films without rubbing could reach 90° when the content of C6BBC4 was 60% or more.At the same time,the alignment stability could meet the industrial requirements.It was considered that the alkoxy spacer,the biphenyl unit and the alkoxy tail may all play important roles in achieving a large pretilt angle even up to 90°,and the introduction of only the alkoxy spacer or alkoxy tail can also improve the pretilt angle,but not by much.展开更多
基金The authors greatly acknowledge the financial support from the National Natural Science Foundation of China(No.51873126)the Fundamental Research Funds for the Central Universities,as well as the funding from the Science&Technology Department(No.2021YFH0123)of Sichuan Province.
文摘Electrically conductive elastomer composites(CECs)with segregated networks of conductive nanofillers show high potential in stretchable strain sensors due to balanced mechanical and electrical properties,yet the sensitivity at low strain is generally insufficient for practical application.Herein,we report an easy and effective way to improve the resistive response to low strain for CECs with segregated network structure via adding stiff alumina into carbon nanostructures(CNS).The CEC containing 0.7 wt%CNS and 5 wt%Al_(2)O_(3) almost sustains the same elasticity(elongation at break of~900%)and conductivity(0.8 S/m)as the control,while the piezoresistive sensitivity is significantly improved.Thermoplastic polyurethane(TPU)composites with a segregated network of hybrid nanofillers(CNS and Al_(2)O_(3))show much higher strain sensitivity(Gauge factor,GF-566)at low strain(45%strain)due to a local stress concentration effect,this sensitivity is superior to that of TPU/CNS composites(GF-11).Such a local stress concentration effect depends on alumina content and its distribution at the TPU particle interface.In addition,CECs with hybrid fillers show better reproducibility in cyclic piezoresistive behavior testing than the control.This work offers an easy method for fabricating CECs with a segregated filler network offering stretchable strain sensors with a high strain sensitivity.
基金the financial support from the National Natural Science Foundation of China (52125301 and 52203123)the Fundamental Research Funds for the Central Universitiespartially sponsored by the Double First-Class Construction Funds of Sichuan University。
文摘The development of a durable metallic coating on diverse substrates is both intriguing and challenging,particularly in the research of metal-conductive materials for applications such as batteries,soft electronics,and beyond.Herein,by learning from the pencil-writing process,a facile solid-ink rubbing technology(SIR-tech)is invented to address the above challenge.The solid-ink is exampled by rational combination of liquid metal and graphite particles.By harnessing the synergistic effects between rubbing and adhesion,controllable metallic skin is successfully formed onto metals,woods,ceramics,and plastics without limitation in size and shape.Moreover,outperforming pure liquid-metal coating,the composite metallic skin by SIR-tech is very robust due to the self-lamination of graphite nanoplate exfoliated by liquid-metal rubbing.The critical factors controlling the structures-properties of the composite metallic skin have been systematically investigated as well.For applications,the SIR-tech is demonstrated to fabricate high-performance composite current collectors for next-generation batteries without traditional metal foils.Meanwhile,advanced skin-electrodes are further demonstrated for stable triboelectricity generation even under temperature fluctuation from-196 to 120℃.This facile and highly-flexible SIR-tech may work as a powerful platform for the studies on functional coatings by liquid metals and beyond.
基金the National Natural Science Foundation(No.52073187)NSAF Foundation(No.U2230202)for their financial support of this project+3 种基金National Natural Science Foundation(No.51721091)Programme of Introducing Talents of Discipline to Universities(No.B13040)State Key Laboratory of Polymer Materials Engineering(No.sklpme2022-2-03)support of China Scholarship Council
文摘Pre-polymerized vinyl trimethoxy silane(PVTMS)@MWCNT nano-aerogel system was constructed via radical polymerization,sol-gel transition and supercritical CO_(2)drying.The fabricated organic-inorganic hybrid PVTMS@MWCNT aerogel structure shows nano-pore size(30-40 nm),high specific surface area(559 m^(2)g^(−1)),high void fraction(91.7%)and enhanced mechanical property:(1)the nano-pore size is beneficial for efficiently blocking thermal conduction and thermal convection via Knudsen effect(beneficial for infrared(IR)stealth);(2)the heterogeneous interface was beneficial for IR reflection(beneficial for IR stealth)and MWCNT polarization loss(beneficial for electromagnetic wave(EMW)attenuation);(3)the high void fraction was beneficial for enhancing thermal insulation(beneficial for IR stealth)and EMW impedance match(beneficial for EMW attenuation).Guided by the above theoretical design strategy,PVTMS@MWCNT nano-aerogel shows superior EMW absorption property(cover all Ku-band)and thermal IR stealth property(ΔT reached 60.7℃).Followed by a facial combination of the above nano-aerogel with graphene film of high electrical conductivity,an extremely high electromagnetic interference shielding material(66.5 dB,2.06 mm thickness)with superior absorption performance of an average absorption-to-reflection(A/R)coefficient ratio of 25.4 and a low reflection bandwidth of 4.1 GHz(A/R ratio more than 10)was experimentally obtained in this work.
基金the financial support from the Jiangsu Provincial Key Research and Development Program (Grant No. BE2019008)the Natural Science Foundation of China (Grant No. 51573103, 21274094 and 21304060)。
文摘Poly(decamethylene terephthalamide/decamethylene isophthalamide)-block-polyvinyl alcoho)(PA10 T/10 IPEG) copolymer/graphene oxide(GO) composites were prepared via in-situ melt polymerization and two different nano-filler addition approaches were compared. The relationship between the micro-structure and performance of the elastomer composites prepared by one-step and two-step methods was explored. The results show that the two-step method significantly promoted the dispersion of the GO in a polymer matrix, and facilitated the grafting of more hard molecular chains. Thus, the elastic modulus and tensile strength of the nanocomposite have been significantly improved by the presence of GO. This was because of the strong interaction between the functional groups on the surface of the GO and the hard molecular chains. This would be also be favorable to load transfer across the interface. Additionally, the elongation at the break of composites increased by 10% with the addition of a small amount of GO(0.2% wt). This is because hard domains tend to be enriched on the surface of GO in composites and act as a lubricating layer at the interface between the GO and matrix, leading to increased deformation ability. This work provides an effective strategy to prepare elastomer composites with high strength and toughness.
文摘A novel phthalonitrile derivative containing an amino group, 3,5-bis(3,4-dicyanophenoxy)aniline (CPA), was synthesized via a nucleophilic displacement of 4-nitrophthalonitrile and 5-aminoresorcinol hydrochloride. The structure of CPA was confirmed by Fourier transform infrared spectra (FT-IR) and nuclear magnetic resonance (1H NMR). Thermal analysis performed on CPA revealed that the novel phthalonitrile derivative showed a self-promotion curing behavior and the resulting polymer exhibited outstanding heat-resistance.
基金Funded by the National Natural Science Foundation of China(No.51103091)Scientific Research Foundation for the Returned Overseas Chinese Scholars State Education Ministry(No.20101174-4-3)the Opening Project of the Key Laboratory of Polymer Processing Engineering,Ministry of Education,China and the Fundamental Research Funds for the Central Universities(No.2012ZM0074)
文摘The rheological behavior, thermal properties and foam morphology of linear polypropylene and long chain branching polypropylene prepared through UV irradiation reactive extrusion were studied by rheological test, melt index test, DSC and supercritical carbon dioxide foaming technology. Rheological test and melt index test confirmed that under UV irradiation and extrusion, adding photo-initiator and cross-linking agent could achieve the purpose of branching, thus improved the melt strength of polypropylene effectively. The DSC results revealed that with the introducing of long chain branching, the melting range of the polypropylene broadened and the crystallization temperature increased. Owing to the introduction of long chain branches, polypropylene exhibited higher melt strength and strain hardening behavior. Compared with linear polypropylene, the foam morphologies of long chain branching polypropylene were more uniform.
基金supported by the National Key R&D Program of China (No. 2021YFA1501700)the Funding for Hundred Talent Program B of Sichuan University (20822041E4079)+2 种基金the Institutional Research Fund from Sichuan University (2020SCUNL205)the State Key Laboratory of Polymer Materials Engineering Open Fund project (sklpme2020-1-02)the Fundamental Research Funds for the Central Universities。
文摘Of all the existing materials, plastics are no doubt among the most versatile ones. However, the extreme increases in plastic production as well as the difficulty of the material for degradation have led to a huge number of plastic wastes. Their recycling rate after disposal is less than 10%, resulting in a series of serious environmental and ecological problems as well as a significant waste of resources. Current recycling methods generally suffer from large energy consumption, the low utilization rate of recycled products with low added value, and produce other waste during the process. Here, we summarized recentlydeveloped chemical recycling ways on commodity plastics, especially new catalytic paths in production of fuels, high-valued chemicals and advanced materials from a single virgin or a mixture of plastic waste,which have emerged as promising ways to valorize waste plastics more economically and environmentally friendly. The new catalyst design criteria as well as innovative catalytic paths and technologies for plastic upcycling are highlighted. Beyond energy recovery by incineration, these approaches demonstrate how waste plastics can be a viable feedstock for energy use with the generation of clean H_(2), high-quality liquid fuels and materials for energy storage, and help inspiring more catalytic process on plastic upcycling to overcome the economical hurdle and building a circular plastic economy.
基金supported by the National Natural Science Foundation of China(No50533050)
文摘Biodegradable composite films based on chitosan and lignin with various composition were prepared via the solution-casting technique.FT-IR results indicate the existence of hydrogen bonding between chitosan and lignin,and SEM images show that lignin could be well dispersed in chitosan when the content of lignin is below 20 wt%due to the strong interfacial interaction.As a result of strong interaction and good dispersion,the tensile strength,storage modulus,thermal degradation temperature and glass transi...
基金Funded by the the National Natural Science Foundation of China(Nos.51173112,51121001)
文摘The present work enhanced the thermal conductivity of poly(p-phenylene sulfi de)/expanded graphites and poly(p-phenylene sulfi de)/carbon nanotubes, by incorporating composites with hexagonal boron nitride, which simultaneously succeeded in raising the electrical conductivity of the systems. A two-step mechanical processing method which includes rotating solid-state premixing and inner mixing was adopted to improve dispersion of the hybrids, contributing to the formation of an interspered thermal conductive network. Similar synergic effect in thermal conductivity enhancement was discovered in the hybrid systems regardless of the dimension difference between the two carbon fi llers. Such is postulated to be the one satisfying advantage generated by the afore-mentioned network; the other is the insulativity of the hybrid systems given by the effective blockage of hexagonal boron nitride as an insulating material in our network.
基金supported by the National Natural Science Foundation of China(No.50527301)
文摘The non-isothermal crystallization of poly(L-lactide)(PLLA) under quiescent and steady shear flow conditions was in situ investigated by using polarizing optical microscopy(POM) with a hot shear stage and wide-angle X-ray diffraction(WAXD).The shear rate and the cooling rate both play a significant role in the final crystalline morphology and crystallinity.Under quiescent conditions,the morphology assumes different sized spherulites,and its crystallinity dramatically reduces with increasing the cooling rate.On the other hand,the shear flow increases the onset crystallization temperature,and enhances the final crystallinity.When the shear rate is above 5 s^(-1),cylindrite-like crystals are observed, furthermore,their content depends on the cooling rate.
文摘The effects of postthermal treatment and irradiation time on the structure and thermal stability of TiO2/polyacrylate nano- composites by a sol-gel process in reverse micelles and subsequent rapid photopolymerization were investigated, and the hybrid films were characterized by thermal gravimetry analysis (TGA), X-ray photoelectron spectrum (XPS), and atomic force microscopy (AFM). XPS data suggested that the prolongation of irradiation time and the postthermal treatment promoted titania formation, with the former affecting more remarkably. TGA data showed that TiO2-hybrid films could upgrade the decomposition onset temperature (Tonset) as well as the temperature at which there is a maximum mass loss rate (Tmax). AFM data demonstrated that the inorganic titania particles with a mean diameter of 25.26-28.84 nm were homogeneously distributed in the organic matrix.
基金Supported by the National Natural Science Foundation of China(No.50973073)the Science and Technology Projects of Chengdu City, China(No.10GGYB114GX-182)
文摘A diamine monomer 4,4′-methylenedianiline(MDA) was introduced to modify the polyimide of pyromellitic dianhydride(PMDA) and 4,4′-oxydianiline(ODA) by polycondensation. A series of polyamic acids was synthesized from MDA and ODA of different molar ratios with PMDA of sum mole of moles of MDA and ODA, and polyimide films were obtained by thermal imidization. Polyimide(PI) films were characterized by tensile testing, dynamic mechanical analysis(DMA), thermal gravimetry analysis(TGA), Fourier transform infrared spectroscopy (FTIR), wide X-ray diffraction(WAXD) and molecular simulation. With the increase of MDA content, the tensile strength and thermal decomposition temperature remained generally stable compared with those of PMDA/ODA polyimide. Unexpectedly, the glass transition temperature(Tg) and Young's modulus increased from 388.7 °C and 2.37 GPa to 408.3 °C and 5.74 GPa, respectively. The results of WAXD and molecular simulation indicate the steric hindrance among hydrogen atoms of the linkage groups and adjacent phenyls enhanced the properties of the polyimide modified with MDA.
基金National Natural Science Foundation of China(51922071,51773139).
文摘Functional polymer composites(FPCs)have attracted increasing attention in recent decades due to their great potential in delivering a wide range of functionalities.These functionalities are largely determined by functional fillers and their network morphology in polymer matrix.In recent years,a large number of studies on morphology control and interfacial modification have been reported,where numerous preparation methods and exciting performance of FPCs have been reported.Despite the fact that these FPCs have many similarities because they are all consisting of functional inorganic fillers and polymer matrices,review on the overall progress of FPCs is still missing,and especially the overall processing strategy for these composites is urgently needed.Herein,a"Toolbox"for the processing of FPCs is proposed to summarize and analyze the overall processing strategies and corresponding morphology evolution for FPCs.From this perspective,the morphological control methods already utilized for various FPCs are systematically reviewed,so that guidelines or even predictions on the processing strategies of various FPCs as well as multi-functional polymer composites could be given.This review should be able to provide interesting insights for the field of FPCs and boost future intelligent design of various FPCs.
文摘In order to resolve the increasing resistance phenomena of the Gram-negative bacteria against single chain quaternary ammonium salts (QAS), lysine with a pedant fluorinated bis-ammonium salts was synthesized and its antimicrobial properties were evaluated in this work. The novel fluorinated bis-ammonium salts shows similar activity with conventional single chain quaternary ammonium salts against Gram-positive bacteria but stronger activity against Gram-negative bacteria and yeast compared with the single chained counterpart.
基金the Natural Science Foundation of China (Grant No. 21274094, 21304060 and 51573103)the Jiangsu Provincial Key Research and Development Program (Grant No. BE2019008) for providing financial support。
文摘Poly(arylene sulfide sulfone)/graphene nanoplate(PASS/GNP) composites with segregated structure based on continuous polymer fiber skeletons were fabricated by coating a thin conductive layer on the PASS fibers and then performing compression molding. The formation of a unique segregated conductive network endowed the PASS/GNP composites with high electrical conductivity and excellent electromagnetic interference(EMI) shielding effectiveness(SE), reaching 17.8 S/m and 30.1 d B, respectively, when the content of the GNPs in the conductive layer was 20 wt%. The PASS/GNP composites also exhibited outstanding mechanical properties, which was attributed to the continuous PASS fiber skeletons that could withstand large loads and the strong interfacial interaction between the conductive layers and the PASS fibers that could provide good stress transfer. This approach is suitable for most soluble polymers.
基金This work was supported by the China National Distinguished Young Investigator Fund (No. 29925413) and the NationalNatural Science Foundation of China (No. 59973013)
文摘It has been well known that fluorinated polyurethanes exhibit uniquely low surface energy, biocompatibility and biostability, thermal and oxidative stability and nonsticking behavior. Consequently, these polymers have attracted considerable interest. However, the mechanical properties of fluorinated polyurethanes usually decline with increasing fluorine contents. The blending of fluorinated polyurethanes with normal polyurethane was carried out to achieve balanced mechanical and surface properties. It was found that polyurethane with good mechanical properties and low surface energy can be obtained by adding a small amount of fluorinated polyurethane. The fluorinated side chains can easily migrate to uppermost surfaces of the blends untill the fluorine level at the surface becomes almost saturated. It has been shown from contact angle, XPS and AFM measurements that only as little as 0.34 wt% of fluorine level is enough to produce a surface saturated with fluorine, and the fluorine level at the uppermost surface is one hundred times higher than that in the blend bulk. The final outer surface structures of the polyurethane blend were independent of the content of the fluorinated polyurethane in the blends due to the surfaces saturated by fluorine.
基金the financial support from the National Science Foundation of China (NSFC) (No.52103178)Science and Technology Project of Sichuan Province (No. 2023NSFSC0997)+2 种基金Sixth Two-hundred Talent B plan of Sichuan Universitysupport by the Australian Research Council Discovery Program (DP190103290)Australian Research Council Future Fellowships (FT200100730, FT210100804)。
文摘Cutting-edge heat spreaders for soft and planar electronics require not only high thermal conductivity and a certain degree of flexibility but also remarkable self-adhesion without thermal interface materials, elasticity, arbitrary elongation along with soft devices, and smart properties involving thermal self-healing, thermochromism and so on. Nacre-like composites with excellent in-plane heat dissipation are ideal as heat spreaders for thin and planar electronics. However, the intrinsically poor viscoelasticity, i.e., adhesion and elasticity, prevents them from simultaneous self-adhesion and arbitrary elongation along with current flexible devices as well as incurring high interfacial thermal impedance. In this paper, we propose a soft thermochromic composite(STC) membrane with a layered structure, considerable stretchability, high in-plane thermal conductivity(~30 Wm^(-1) K^(-1)), low thermal contact resistance(~12 mm^2 KW^(-1), 4–5 times lower than that of silver paste), strong yet sustainable adhesion forces(~4607 Jm^(-2), 2220 Jm^(-2) greater than that of epoxy paste) and self-healing efficiency. As a self-adhesive heat spreader, it implements efficient cooling of various soft electronics with a temperature drop of 20℃ than the polyimide case. In addition to its self-healing function, the chameleon-like behavior of STC facilitates temperature monitoring by the naked eye, hence enabling smart thermal management.
基金Supported by the National Natural Science Foundation of China(Nos.50773044,50973073)
文摘A novel biphenyl side-chained diamine with alkyloxy spacer and alkyloxy tail,4'-butoxy-4-(3,5-diaminobenzoyloxy)hexyloxybiphenyl(C6BBC4),was synthesized and characterized by FTIR and 1 H NMR.A series of polyimide(PI) films with different side chain contents was synthesized from biphenyltetracarboxylicdianhydride(BPDA),4,4'-oxydianiline(ODA) and C6BBC4,and their thermal properties,optical transparency and liquid crystal alignment property,and so on,were investigated by thermogravimetric analysis(TGA),differential scanning calorimetry(DSC),crystal rotation method,polarizing microscopy and UV-Vis spectra.With the content of side chained diamine increasing from 0 to 100%,the η inh of poly(amide acid)(PAA) decreased rapidly from 3.0 to 0.51,the glass transition temperature(T g) of polyimides(PIs) decreased from 274 ℃ to 203 ℃ and the Vis-light transmittance of alignment films substantially increased.As for the alignment properties,the pretilt angle of PI alignment films without rubbing could reach 90° when the content of C6BBC4 was 60% or more.At the same time,the alignment stability could meet the industrial requirements.It was considered that the alkoxy spacer,the biphenyl unit and the alkoxy tail may all play important roles in achieving a large pretilt angle even up to 90°,and the introduction of only the alkoxy spacer or alkoxy tail can also improve the pretilt angle,but not by much.
