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Facile fabrication of highly durable superhydrophobic strain sensors for subtle human motion detection

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Journal of Materials Science & Technology 2022年第15期110卷 35-42页

作者： li-Chuan Jia Chang-Ge Zhou Kun Dai Ding-Xiang Yan zhong-ming li College of Electrical Engineering Sichuan UniversityChengdu 610065China College of Polymer Science and Engineering State Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu 610065China College of Materials Science and Engineering The Key Laboratory of Material Processing and Mold of Ministry of EducationZhengzhou UniversityZhengzhou 450001China School of Aeronautics and Astronautics Sichuan UniversityChengdu 610065China

Endowing strain sensors with superhydrophobicity is of great importance to guarantee their long-term service under harsh environments(such as wet,acid,alkali and salt atmospheres),whereas,the development of superhydrophobic strain sensors remains a great ***,we realized a superhydrophobic and highly sensitive sensor for subtle human motion detection by designing a superhydrophobic and electrically conductive coating on cotton textile,via a facile drop-coating *** resultant strain sensor showed a large water contact angle of 161.3°and a low sliding angle of 3.8°The superhydrophobic characteristics can keep almost unchanged even after undergoing 1000 peeling cycles,1000 stretchingrelease cycles,and 1000 bending-releasing cycles,revealing its excellent mechanical *** sensitivity with the maximum gage factor of 169 was achieved for the strain sensor under a small strain of0–10%,and the sensing performance also showed well ***,our sensor can effectively detect various subtle human physiological signals and body motions even under harsh *** admirable features make the sensor promising applications in wearable electronics,personalized health monitoring,sound recognition,and so on.

关键词： Strain sensors Superhydrophobicity High sensitivity Drop coating Durable

Flexible Polydimethylsiloxane Composite with Multi-Scale Conductive Network for Ultra-Strong Electromagnetic Interference Protection

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Nano-Micro Letters 2023年第1期15卷 293-306页

作者： Jie li He Sun Shuang-Qin Yi Kang-Kang Zou Dan Zhang Gan-Ji zhong Ding-Xiang Yan zhong-ming li College of Polymer Science and Engineering State Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu 610065People’s Republic of China School of Aeronautics and Astronautics Sichuan UniversityChengdu 610065People’s Republic of China

Highly conductive polymer composites(CPCs) with excellent mechanical flexibility are ideal materials for designing excellent electromagnetic interference(EMI) shielding materials,which can be used for the electromagnetic interference protection of flexible electronic *** is extremely urgent to fabricate ultra-strong EMI shielding CPCs with efficient conductive *** this paper,a novel silver-plated polylactide short fiber(Ag@PL ASF,AAF) was fabricated and was integrated with carbon nanotubes(CNT) to construct a multi-scale conductive network in polydimethylsiloxane(PDMS) *** multi-scale conductive network endowed the flexible PDMS/AAF/CNT composite with excellent electrical conductivity of 440 S m-1and ultra-strong EMI shielding effectiveness(EMI SE) of up to 113 dB,containing only 5.0 vol% of AAF and 3.0 vol% of CNT(11.1wt% conductive filler content).Due to its excellent flexibility,the composite still showed 94% and 90% retention rates of EMI SE even after subjected to a simulated aging strategy(60℃ for 7 days) and 10,000 bending-releasing *** strategy provides an important guidance for designing excellent EMI shielding materials to protect the workspace,environment and sensitive circuits against radiation for flexible electronic devices.

关键词： Flexible conductive polymer composites Silver-plated polylactide short fiber Carbon nanotube Electromagnetic interference shielding Multi-scale conductive network

A new C_(27)-steroidal glycoside from Ophiopogon japonicus

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Chinese Chemical Letters 2008年第1期19卷 82-84页

作者： Jian zhong Wang li ming Ye Xiao Bing Chen West China College of Pharmacy Sichuan University Chengdu 610041 China

A new C27-steroidal glycoside with three known compounds were isolated from the tuber of Ophiopogonjaponicus （Thunb.） Ker-Gawl. Based on the spectral analysis, including HRMS, 1H NMR, 13C NMR, DEPT, 1H-1H COSY, HMQC and HMBC, their chemical structures were determined as pennogenin-3-O-α-L-rhamnopyranosyl-（1→ 2）-β-D-xylopyranosyl-（1→ 4）-13-D-gluco- pyranoside （1）, pennogenin-3-O-α-L-rhamnopyranosyl-（1→ 2）-β-D-glucopyranoside （2）, ophiopojaponin C （3） and ophiopogonin D （4）. 2007 Jian zhong Wang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

关键词： Ophiopogon japonicus C27-steroidal glycoside

The Crystallization Behavior of Biodegradable Poly(butylene succinate) in the Presence of Organically Modified Clay with a Wide Range of Loadings

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Chinese Journal of Polymer Science 2015年第4期33卷 576-586页

作者： Jing-bin Chen Jia-zhuang Xu Huan Xu zhong-ming li 钟淦基雷军 College of Polymer Science and Engineering and State Key Laboratory of Polymer Materials Engineering Sichuan University

The crystallization behavior of poly（butylene succinate）（PBS） nanocomposites with a wide range of contents of clays was revealed. It was of interest to find that the crystallization rate of PBS was accelerated obviously at relatively low contents of clays; while a retarded crystallization kinetics and a decreased crystallinity of PBS were found in the nanocomposites with higher clay contents. Two interplaying effects existed in the nanocomposites, i.e., a suppression effect of clays on nucleation and a templating effect of clays on crystal growth, were clarified to contribute to this intriguing crystallization behavior.

关键词： Poly(butylene succinate) Clay Crystallization kinetics Biodegradable.

Towards Efficient Electromagnetic Interference Shielding Performance for Polyethylene Composites by Structuring Segregated Carbon Black/Graphite Networks

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Chinese Journal of Polymer Science 2016年第12期34卷 1490-1499页

作者： Cheng-hua Cui 鄢定祥 Huan Pang li-chuan Jia Yu Bao Xin Jiang zhong-ming li College of Polymer Science and Engineering State Key Laboratory of Polymer Materials EngineeringSichuan University

An electromagnetic interference （EMI） shielding composite based on ultrahigh molecular weight polyethylene （UHMWPE） loaded with economical graphite-carbon black （CB） hybrid fillers was prepared via a green and facile methodology, i.e., high-speed mechanical mixing combined with hot compression thus avoiding the assistance of the intensive ultrasound dispersion in volatile organic solvents. In this composite, the graphite-CB hybrid fillers were selectively distributed in the interfacial regions of UHMWPE domains resulting a typical segregated structure. Thanks to the specific morphology of segregated conductive networks along with the synergetic effect of large-sized graphite flakes and small-sized CB nanoparticles, a low filler loading of 7.7 vol% （15 wt%） yielded the graphite-CB/UHMWPE composites with a satisfactory electrical conductivity of 33.9 S/m and a superior shielding effectiveness of 40.2 dB, manifesting the comparable value of the pricey large-aspect-ratio carbon nanofillers （e.g., carbon nanotubes and graphene nanosheets） based polymer composites. More interestingly, with the addition of 15 wt% graphite-CB （1/3, W/W） hybrid fillers, the tensile strength and elongation at break of the composite reached 25.3 MPa and 126%, respectively; with a remarkable increase of 58.1% and 2420% over the conventional segregated graphite/UHMWPE composites. The mechanical reinforcement could be attributed to the favor of the small-sized CB particles in the polymer molecular diffusion between UHMWPE domains which in tuna provided a stronger interfacial adhesion. This work provides a facile, green and affordable strategy to obtain the polymer composites with high electrical conductivity, efficient EMI shielding, and balanced mechanical performance.

关键词： Graphite Carbon black Segregated structure Electromagnetic interference Synergistic effect.

Vibration Assisted Extrusion of Polypropylene

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Chinese Journal of Polymer Science 2015年第5期33卷 688-696页

作者： Fang-zhen An 高雪芹雷军 Cong Deng zhong-ming li Kai-zhi Shen Department of Polymer Science and Materials State Key Laboratory of Polymer Materials EngineeringSichuan University Analytical and Testing Center Sichuan University

A new homemade apparatus, i.e. vibration assisted extrusion equipment, is employed to extrude polypropylene. Vibration assisted extrusion is based on the application of a specific macroscopic shear vibration field. Reduction of apparent melt viscosity as a function of vibration frequency is measured at different screw speeds and die temperatures. The effect of the process is investigated by performing mechanical tests, differential scanning calorimetry studies, polarized light microscopy and wide-angle X-ray diffraction. It is found that, compared with conventional extrusion, vibration assisted extrusion could effectively improve the rheological properties of PP melt by incorporating an extra shear vibration field. Both the tensile strength and elongation at break increased under the shear vibration field. For vibration assisted extrusion samples, both the melting temperature and crystallinity increased, accompanied by remarkable grain refinement. Vibration assisted extrusion induced a significantly enhanced bimodal orientation with a high fraction of a^＊-oriented α-crystallites, while only a limited improvement in the flow direction orientation. A structural model, i.e. bimodal c-axis and a^＊-axis orientation of PP macromolecular chains, was adopted to explain the experimental results.

关键词： Vibration assisted extrusion Polypropylene Mechanical properties Microstructure

Superior Ductile and High-barrier Poly(lactic acid)Films by Constructing Oriented Nanocrystals as Efficient Reinforcement of Chain Entanglement Network and Promising Barrier Wall

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Chinese Journal of Polymer Science 2022年第10期40卷 1201-1212,I0009页

作者： lin Zhou Ping-Ping Xu Shi-Hao Ni ling Xu Hao lin Gan-Ji zhong Hua-Dong Huang zhong-ming li Collge of Polymer Science and Engineering State Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu 610065China

It is a daunting task to develop a promising strategy at an industrial scale for simultaneously ameliorating ductility and gas barrier performance of poly(lactic acid)(PLA)films in the application of green *** this work,biaxial stretching and constrained annealing were employed to prepare transparent PLA films with superior ductility and barrier *** oriented nano-sized crystals induced by biaxial stretching were developed into regularαform during constrained annealing,which could not only serve as“nano-barrier wall”to impede the diffusion and dissolution of gas molecules,but also strengthen amorphous chain entanglement network as physical crosslink to enhance *** a result,the as-prepared PLA films exhibited an outstanding comprehensive performance with a low oxygen and water vapor permeability coefficient of 0.733×10^(-14) cm^(3)·cm·cm^(-2)·s^(-1)·Pa^(-1) and 3.82×10^(-14) g·cm·cm^(-2)·s^(-1)·Pa^(-1),respectively,outstanding ductility with elongation at break of 66.0%,high yield strength of 84.2 MPa,and good transparency of more than 80%at 550 *** new insight in the relationship between microscopic amorphous and crystalline structure and macroscopic performance is conducive to alleviating the intrinsic defects of brittle and insufficient barrier PLA films without the aid of any heterogenous modifiers,facilitating their widespread commercialization in the booming sustainable packaging market.

关键词： Poly(lactic acid)films Biaxial stretching Constrained annealing Gas barrier properties Ductility

How the Aggregates Determine Bound Rubber Models in Silicone Rubber? A Contrast Matching Neutron Scattering Study

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Chinese Journal of Polymer Science 2021年第3期39卷 365-376,I0007页

作者： li-Zhao Huang Yue Shui Wei Chen zhong-ming li Hong-Tao Song Guang-Ai Sun Jia-Zhuang Xu Gan-Ji zhong Dong liu Key Laboratory of Neutron Physics and Institute of Nucear Physics and Chemistry(NPC) China Academy of Engineeing Physict(CAEP)Mcnyang 621999China National Synchrotron Radiation Lab CAS Key Laboratory of soft Mtter Chemisty Anhui Provincial fngineing Laboratory of Advanced funcionad Poymer FilmUniversity of Science and Technology of ChinaHefei 230026China College of Polymer cience and Engineering state Key Laboratory of Polymer Materials Engineering Sichuan UniversityChengdu 61065China

The correlation between aggregates and bound rubber structures in silicone rubbers(S(phr)) with various silica fractions(ΦSi) has been investigated by contrast matching small-angle neutron scattering(SANS), swelling kinetics, and low-field nuclear magnetic resonance(NMR).Mixed solvents with deuterated cyclohexane fractions of 4.9% and 53.7% were chosen to match the scattering length densities of the matrix(SMP(phr)) and the filler(SMS(phr)), respectively. All the data consistently suggest that:(i) There is a critical threshold ΦSic between 10 and 30 phr;below ΦSic, the isolated aggregates are dominant, while beyond ΦSic, some rubber fraction is trapped among the agglomerate;(ii) ΦSiindependent thicknesses around 7.5 nm(NMR) and 8.6 nm(SANS) suggest that the bound rubber formation is determined by inherent properties of the components, and the power-law around 4.2 suggests an exponential changed gradient density of the bound rubber;(iii) SMS(80) presents a bicontinuous bound rubber with three characteristic lengths of 41, 100, and 234 nm. The expanded correlation length, a 20 nm smaller aggregate sizes suggest that such existent bicontinuous network in dry samples with less ΦSi is kind of impacted by swelling. With the obtained bound rubber models, the reinforcing mechanism of filled silicone rubber is elucidated.

关键词： Silicone rubber Bound rubber structures Small-angle neutron scattering(SANS) Nuclear magnetic resonance(NMR)

Temperature-dependent β-Crystal Growth in Isotactic Polypropylene with β-Nucleating Agent after Shear Flow

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Chinese Journal of Polymer Science 2017年第12期35卷 1540-1551页

作者：陈妍慧 Hao-qing Yang Song Yang Qiu-yu Zhang zhong-ming li Department of Applied Chemistry School of Science Northwestern Polytechnical University College of Polymer Science and Engineering and State Key Laboratory of Polymer Materials Engineering Sichuan University

In our current work, the effect of the shear temperature on the growth of β-crystal in isotactic polypropylene（iPP） with β-nucleating agent is investigated by means of in situ two-dimensional wide-angle X-ray diffraction（2 D-WAXD）. At low shear temperatures, the formed shear-induced oriented precursors are hard to relax back to random coiled state due to the weak mobility of molecular chains. Therefore, plenty of oriented α-crystals are induced by shear-induced oriented precursors, while β-crystal is greatly depressed. As the shear temperature increases, oriented β-crystal gradually increases along with the decrease of α-crystal. It is deduced that the shear temperature at which the content of β-crystal increases to the（maximum） value found in quiescent crystallization is almost the same as that at which the accelerating effect of flow on crystallization kinetics is completely erased. Our work manifests its significance in regulating β-crystal and thus in the structure and property manipulation of i PP.

关键词： Isotactic polypropylene β-Crystal Crystallization Shear temperature