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Efficient Electromagnetic Wave Absorption and Thermal Infrared Stealth in PVTMS@MWCNT Nano‑Aerogel via Abundant Nano‑Sized Cavities and Attenuation Interfaces

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Nano-Micro Letters 2024年第1期16卷 370-383页

作者： Haoyu Ma Maryam Fashandi Zeineb Ben Rejeb Xin Ming Yingjun Liu Pengjian Gong Guangxian Li Chul B.Park College of Polymer Science and Engineering State Key Laboratory of Polymer Materials EngineeringSichuan University24 Yihuan RoadNanyiduanChengdu 610065SichuanPeople’s Republic of China Microcellular Plastics Manufacturing laboratory Department of Mechanical and Industrial EngineeringUniversity of Toronto5 King’s College RoadTorontoON M5S 3G8Canada Jiangsu JITRI Advanced Polymer Materials Research Institute Tengfei Building88 Jiangmiao RoadJiangbei New DistrictNanjing 211800JiangsuPeople’s Republic of China MOE key laboratory of macromolecular synthesis and functionalization Department of Polymer Science and EngineeringInternational Research Center for X PolymersZhejiang University38 Zheda RoadHangzhou 310027People’s Republic of China

Pre-polymerized vinyl trimethoxy silane(PVTMS)@MWCNT nano-aerogel system was constructed via radical polymerization,sol-gel transition and supercritical CO_(2)*** 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.

关键词： Nano-pore size Heterogeneous interface Electromagnetic wave absorption Thermal infrared stealth Nano-aerogel

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synthesis of biheteroaryls via 2-methyl quinoline C(sp^(3))-H functionalization under metal-free conditions

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Green synthesis and Catalysis 2024年第1期5卷 73-76页

作者： Dahan Wang Yuhan Yang Fuhong Xiao Jinbing Liu Guojiang Mao Guo-Jun Deng key laboratory of Environmentally Friendly Chemistry and Application of ministry of education Hunan Province Key Laboratory of Green Organic Synthesis and ApplicationCollege of ChemistryXiangtan UniversityXiangtan 411105China Department of Food and Chemical Engineering Shaoyang UniversityShaoyang 422100China School of Chemistry and Chemical Engineering Henan Normal UniversityXinxiang 453007China

An acetic acid-promoted C(sp^(3))-H functionalization of 2-methyl quinoline,enaminoesters and elemental sulfur for the synthesis of 3,4,5-trisubstituted isothiazoles under metal-free conditions has been *** approach provides viable access to various 5-(quinolin-2-yl)isothiazoles in moderate to good yields with good functional group ***,the success of the gram-scale reaction gives this reaction a great potential application.

关键词： C(sp^(3))-H functionalization Multicomponent reactions Biheteroaryls Elemental sulfur Metal-free

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MECHANICAL AND THERMAL PROPERTIES OF NANOSIZED TITANIUM DIOXIDE FILLED RIGID POLY(VINYL CHLORIDE)

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Chinese Journal of Polymer Science 2013年第2期31卷 325-332页

作者： Yun-xiang Zhang 宋义虎 Qiang Zheng key laboratory of macromolecular synthesis and functionalization of ministry of education Department of PolymerScience and Engineering Zhejiang University

Nano-sized rod-like titanium dioxide （TiO2） filled rigid poly（vinyl chloride）（PVC） nanocomposites were prepared by using injection-molding method. Vicat, Charpy impact and tensile tests as well as thermogravimetric and dynamic mechanical analyses were used to characterize the structure and properties of the nanocomposites. The results showed that nano-TiO2 could improve Vicat softening temperature and also improve thermal stability of PVC during the stages of dehydrochlorination and formation of carbonaceous conjugated polyene sequences, which can be ascribed to restriction of the nanoparticles on the segmental relaxation as being evidenced by raises in glass transition and β-relaxation temperatures of PVC upon filling TiO2. Addition of TiO2 nanoparticles less than 40 phr （parts per hundreds of resin） could significantly improve impact strength of the composites while the TiO2 agglomeration at high contents leads to a reduction in impact toughness.

关键词： Poly(vinyl chloride) (PVC) Titanium dioxide (TiO2) Thermal property Mechanical property Impact strength.

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Deactivation Effect Caused by Catalyst-Cocatalyst Pre-contact in Propylene Polymerization with MgCl2-supported Ziegler-Natta Catalyst

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Chinese Journal of Polymer Science 2019年第10期37卷 1023-1030,I0005页

作者： Zhen Zhang Bai-Yu Jiang Biao Zhang Zhi-Sheng Fu Zhi-Qiang Fan ministry of education key laboratory of macromolecular synthesis and functionalization Department of Polymer Science and Engineering Zhejiang University

Propylene slurry polymerization with a MgCl2-supported Ziegler-Natta catalyst containing internal electron donor was conducted after different durations of pre-contact of the catalyst with triethylaluminum cocatalyst. The number of active centers([C*]/[Ti])was determined by quenching the polymerization with 2-thiophenecarbonyl chloride and measuring sulfur content in the polymer. The pre-contact treatment caused selective deactivation of a part of active centers with low stereoselectivity and much lower activity in the initial stage of polymerization as compared with the polymerization run without the pre-contact stage. The active center concentration and polymerization activity decreased with prolonging of the pre-contact stage. The proportion of stereoselective active centers was increased by prolonging the pre-contact stage, so the isotacticity of produced polypropylene was enhanced. Release of active centers through catalyst particle fragmentation was significantly retarded, and the polymerization rate curve changed from decay type to induction type by the precontact treatment. In the induction period both non-stereoselective and stereoselective active centers were released and activated, resulting in gradual reduction of the polymer’s isotacticity in the first 5-10 min of polymerization. Selective deactivation of non-stereoselective active centers also took place in propylene polymerization using the catalyst without pre-contacting with the cocatalyst. In this case, the polymerization rate decayed with time after a short induction period of 2-5 min. Over reduction of the active center precursors with low stereoselectivity by triethylaluminum was considered as the reason for their deactivation during the pre-contact or the polymerization processes.

关键词： Propylene Polymerization Supported Ziegler-Natta catalyst Cocatalyst Pre-contact

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Facile synthesis of Functional Poly (ε-caprolactone) via Janus Polymerization

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Chinese Journal of Polymer Science 2019年第9期37卷 858-865页

作者： Huan Qiu Zhe-Ning Yang Jun Ling ministry of education key laboratory of macromolecular synthesis and functionalization Department of Polymer Science and Engineering Zhejiang University

Functionalized aliphatic polyesters attract increasing attentions as biocompatible and biodegradable polymers with broad applications in biological science. In this contribution, we propose a facile and controllable synthetic technique for functional poly(ε-caprolactone)(PCL) via Janus polymerization, which comprises cationic ring-opening copolymerization (ROP) of ε-caprolactone (CL) with 3,3-bis(chloromethyl)oxacyclobutane (CO) and (coordinated) anionic ROP of CL at a single propagating chain by rare earth metal triflates (RE(OTf)3)and propylene oxide, thus generating block copolymers in one step. The compositions of the copolymers of poly(CLb-(CL-r-CO)) can be modulated by various RE(OTf)3. Scandium triflate catalyzes Janus polymerization to yield the copolymers containing the highest CO contents among all the RE(OTf)3 catalysts used with complete conversion of CL. The chlorine in CO repeating units is ready to be transferred into azide group which affords the modification sites to react with 9-ethynyl-9-fluorenol and mPEG-alkyne, respectively, via copper(I)-catalyzed azide-alkyne cycloaddition reaction with quantitative conversions of azides, as confirmed by FTIR analyses. According to NMR and SEC analyses, copolymers (PCC-g-PEG) bearing a homo-PCL block and a PEG-grafted block of poly(CO-co-CL) demonstrate well-defined chemical structures. The investigations on thermal properties reveal the strong phase separation between PCL and PEG blocks. The amphiphilic PCC-g-PEG is able to sei住assemble into micelles in aqueous solution while cylindrical and lamellar morphologies are observed in bulk. We provide an efficient protocol to synthesize functional PCL combining onestep Janus polymerization and precise post-polymerization click reaction.

关键词： Janus polymerization Functional poly(ε-caprolactone) Poly(3,3-bis(chloromethyl)oxacyclobutane) Ring-opening polymerization Rare earth metal catalysts

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INFLUENCE OF LANTHANUM STEARATE AND CALCIUM/ZINC STABILIZERS ON STABILIZATION EFFICIENCY OF DIBUTYLTIN DILAURATE TO POLYVINYL CHLORIDE

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Chinese Journal of Polymer Science 2010年第4期28卷 637-645页

作者：郑强 Department of Polymer Science and Engineering Zhejiang UniversityKey Laboratory of Macromolecular Synthesis and Functionalization of Ministry of Education

Influences of lanthanum stearate （LaSt3） and calcium stearate/zinc stearate （Ca/Zn） stabilizers on stabilization efficiency of dibutyltin dilaurate （DBTDL） to polyvinyl chloride （PVC） in air were investigated. The results revealed that the stabilization effect of DBTDL could be achieved by the La/Sn stabilizers with a ratio of 8/2. Addition of DBTDL could enhance thermal property and reduce dynamic storage modulus （G＇） at 180℃ for PVC containing LaSt3 or Ca/Zn stabilizers. On the other hand, incorporation of LaSh did not influence the stabilization efficiency of DBTDL markedly; while addition of Ca/Zn stabilizers could significantly decrease thermal property for the DBTDL stabilized PVC. Furthermore, the effects of LaSt3 and Ca/Zn stabilizers on the stabilization efficiency of DBTDL were explained in the framework of ionization potential.

关键词： Polyvinyl chloride (PVC) Calcium/zinc stabilizers Lanthanum stearate Dibutyltin dilaurate Ionization potential.

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Comparative Studies on Properties of Polymers with Bulky Side Groups Synthesized by Cyclopolymerization of α,ω-Dienes and α,ω-Diynes

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Chinese Journal of Polymer Science 2019年第2期37卷 149-156页

作者： Shao-Fei Song Xiao-Yu Liu Hao Zhang Zhi-Sheng Fu Jun-Ting Xu Zhi-Qiang Fan ministry of education key laboratory of macromolecular synthesis and functionalization Department of Polymer Science and Engineering Zhejiang University

Four polymers containing five-membered rings in the main chain, with or without conjugation structure along the backbone and with or without conjugated pendent groups, were designed and synthesized by metathesis cyclopolymerization of functionalized α,ω-diynes, and cyclopolymerization of functionalized α,ω-dienes catalyzed by the α-diimine palladium-based catalyst, respectively. High to moderate monomer conversions were achieved. Chain structure, molecular weight, and molecular weight distribution(MWD) of the cyclopolymerization products were characterized by ~1 H-, ^(13) C-NMR, FTIR, and GPC. The polymers showed regular main chain structures,moderately high molecular weight, and narrow MWD. Thermal properties and chain stacking behaviors of the polymers were investigated by differential scanning calorimetry(DSC) and X-ray diffraction(XRD) as well as atomic force microscopy(AFM). The polymer with conjugation system in both the backbone and the pendent groups exhibited UV-Vis absorption at a much longer wavelength than those with the conjugation only in the backbone or only in the side groups. The polymers with conjugated backbone need more space for chain stacking, and the conjugated backbone causes enhanced size of polymer particles assembled from solution. The results showed that primary microstructures of the polymer exerted significant influences on the physical properties.

关键词： Cyclopolymerization α,ω-Diene α,ω-Diyne Conjugation system Properties

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Recent Progress on COS-derived Polymers

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Chinese Journal of Polymer Science 2019年第10期37卷 951-958,I0002页

作者： Cheng-Jian Zhang Xing-Hong Zhang key laboratory of macromolecular synthesis and functionalization (ministry of education) Department of Polymer Science & Engineering Zhejiang University

The synthesis of sulfur-containing polymer, a very promising functional material, has made a great progress in the past several years. This review is focused on the very recent advances in poly(monothiocarbonate)s derived from carbonyl sulfide(COS) and epoxides including biomass-derived epoxides. Of significance, metal-free catalyst systems, including triethyl borane/Lewis base pair and thiourea/Lewis base pair are developed for the alternating copolymerization of COS with epoxides. Thereof, the thiourea/Lewis base pair is highly active to the copolymerization of COS with epoxide in a living manner. Moreover, a series of crystalline poly(monothiocarbonate)s are presented, including the copolymers derived from COS with oxetane, ethylene oxide, enantiopure epichlorohydrin, and achiral mesoepoxides via enantioselective copolymerization. Based on these COS/epoxide copolymerization process, a variety of COS-based block copolymers with well-defined structure are presented.

关键词： Carbonyl sulfide Epoxide Copolymerization Poly(monothiocarbonate)

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PERVAPORATION FOR SEPARATING BENZENE/CYCLOHEXANE MIXTURE BY P(AA-MA) COPOLYMER MEMBRANES

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Chinese Journal of Polymer Science 2011年第3期29卷 288-295页

作者：朱蔚璞 Department of Polymer Science and Engineering Key Laboratory of Macromolecular Synthesis and Functionalization (Ministry of Education)Zhejiang University

P（AA-MA） copolymers composed of acrylic acid and methyl acrylate with different molecular weights and sequence structures were synthesized by combination of ATRP and selective hydrolysis. These copolymers were used as membrane materials to separate benzene/cyclohexane mixture by pervaporation. The effects of molecular weight and sequence structure of the copolymers on the pervaporation performance were investigated in detail. For the random copolymers, the permeate flux decreased rapidly with the increasing of molecular weight. The separation factor was also influenced by the molecular weight, which was changed from no selectivity to cyclohexane selectivity with increasing the molecular weight. Contrarily, the block copolymer membrane showed good benzene selectivity with separation factor of 4.3 and permeate flux of 157 g/（m2h） to 50 wt% benzene/cyclohexane mixture.

关键词： Pervaporation ATRP Copolymer Molecular weight Sequence structure Benzene/cyclohexane mixture.

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STUDY ON HIGH WELD STRENGTH OF IMPACT PROPYLENE COPOLYMER/HIGH DENSITY POLYETHYLENE LAMINATES

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Chinese Journal of Polymer Science 2011年第4期29卷 497-505页

作者：上官勇刚郑强 key laboratory of macromolecular synthesis and functionalization Ministry of Education Department of Polymer Science and Engineering Zhejiang University

The impact propylene copolymer （IPC） and isotactic polypropylene （iPP） were separately selected to prepare laminates with high density polyethylene （HDPE） by hot press. The peel forces of IPC/HDPE and iPP/HDPE laminates were examined, and it was found that the welded joint strength in IPC/HDPE laminate was dramatically higher than that of iPP/HDPE laminate. According to the special microstructure of IPC, the co-crystallization of the ethylene segments in ethylene-propylene block copolymer （EbP） component of IPC and the PE chain in HDPE was proposed to explain the high- strength welding. The DSC results indicated that there indeed existed some interaction between IPC and HDPE, and the crystallizable PE component in IPC could affect the crystallization of HDPE. The scanning electron microscope （SEM） observations of IPC/HDPE blends demonstrated that HDPE tended to stay with the PE-rich EbP chains to form the dispersed phase, indicating the good miscibility between HDPE and EbP components of IPC. According to the above results, the effect of co-crystallization of the PE components of the IPC and HDPE on the high weld strength of IPC/HDPE laminate was confirmed.

关键词： Impact propylene copolymer Polyethylene Cocrystallization High weld strength.

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