The kinetics of I-->N transition of a side chain nematic polymethacrylate has been studied by small angle depolarized light scattering intensity measurements using a charge coupled device linear image sensor. The p...The kinetics of I-->N transition of a side chain nematic polymethacrylate has been studied by small angle depolarized light scattering intensity measurements using a charge coupled device linear image sensor. The polymer shows the transition temperatures K52N79I in degreesC, The H-v scattering intensity T(q,t) during the transition I (at 80.2degreesC)-->N (at 75.8degreesC) shows that T(q) is independent of q for all t, and during the initial stage (in 6 s) T(t) increases exponentially with t. In the later stage of the transition T(t) approaches a saturation value in 2 min. This experimental result indicates that the I-->N transition of a liquid crystalline polymer is a spinodal type of phase transition mediated by orientation fluctuation.展开更多
Two grafting methods, i.e. solution grafting and pre-adsorbing, are introduced to covalently immobilizehydrophilic polymers on segmented polyurethane (SPU) to modify its hydrophilicity and to improve its cell compatib...Two grafting methods, i.e. solution grafting and pre-adsorbing, are introduced to covalently immobilizehydrophilic polymers on segmented polyurethane (SPU) to modify its hydrophilicity and to improve its cell compatibility.Solution grafting results in higher degree of grafting and rougher surface morphology. Cell culture evaluation demonstratesthat the modified membranes thus obtained are disadvantageous to the endothelial cell (ECs) growth probably because thehydrophilic groups on the surface are over-crowded. However, pre-absorbing grafting generates lower degree of grafting,which is detected and confirmed by ATR-FTIR spectra and water conted angle. Scanning electron microscopic (SEM)measurement shows that the latter method produces a plane and smooth morphology, which is similar to the SPU controlsample controlled. When grafting with lower monomer concentration, ECs could grow on SPU-g-PHEA [poly(2-hydroxyethyl acrylate)], SPU-g-PAAm (polyacrylamide), SPU-g-PDMA [poly(2-(dimethylamino)ethyl methacrylate)] orquatemized SPU-g-PDMA surface with elongated cell shapes. Hence, the cell compatibility of SPU is improved and a usefulmethod to construct a cell compatible layer on the polymer surface has been developed.展开更多
In this study, a novel H-bonded cholesteric polymer film responding to temperature and pH by changing the reflection color was fabricated. The H-bonded cholesteric polymer film was achieved by UV-photopolymerizing a c...In this study, a novel H-bonded cholesteric polymer film responding to temperature and pH by changing the reflection color was fabricated. The H-bonded cholesteric polymer film was achieved by UV-photopolymerizing a cholesteric liquid crystal （Ch-LC） monomers mixture containing a photopolymerizable chiral H-bonded assembly （PCHA）. The cholesteric polymer film based on PCHA can be thermally switched to reflect red color from the initial green/yellow color as temperature is increased, which is due to a change in helical pitch induced by the weakening of H-bonded interaction in the polymer film. Additionally, the selective reflection band （SRB） of the cholesteric polymer film in solution with pH 〉 7 showed an obvious red shift with increasing pH values. While the SRB of the cholesteric polymer film in solutions with pH = 7 and pH 〈 7 hardly changed. This pH sensitivity in solutions with pH 〉 7 could be explained by the breakage of H-bonds in the cholesteric polymer film and the structure changes induced by --OH- and --K＋ ions in the alkaline solution. In contrast, it couldn＇t happen in the neutral and acidic solutions. The cholesteric polymer film in this study can be used as optical/photonic papers, optical sensors and LCs displays, etc.展开更多
Polymerization of acrylonitrile (AN) in aqueous nitric acid initiated by polypropylene-based polyamidoxime (PPAO)-thiourea (TU) combination has been investigated. The overall rate of polymerization (R_p) under the con...Polymerization of acrylonitrile (AN) in aqueous nitric acid initiated by polypropylene-based polyamidoxime (PPAO)-thiourea (TU) combination has been investigated. The overall rate of polymerization (R_p) under the conditions of [TU]/[PPAO]<0.5 molar ratio isThe molecular weights of the polymers were found to be inversely proportional to 3/2-power of nitric acid concentration and 1-power of thiourea concentration. In addition, it is independent with the concentrations of monomer and PPAO, and decreases with increasing temperature.On the basis of these experimental results, a coordination-proton transfer mechanism for the initiation was proposed and discussed.展开更多
Ferroelectric poly(vinylidene fluoride-trifluoroethylene)(P(VDF-TrFE))/semiconducting poly(3-hexyl thiophene)(P3HT)blend systems have drawn great attention with their potential use for electronic applications,particul...Ferroelectric poly(vinylidene fluoride-trifluoroethylene)(P(VDF-TrFE))/semiconducting poly(3-hexyl thiophene)(P3HT)blend systems have drawn great attention with their potential use for electronic applications,particularly non-volatile memory devices.It is essential to grasp a full understanding of the crystallization habits of the two polymers on different substrates for purposeful control of the structures of the blend and therefore the properties of the devices.Here,the effects of structure and morphology of the blend films generated at different substrate surfaces on the ferroelectric and switching properties of related devices are reported.It is identified that P(VDF-TrFE)/P3HT blend films prepared on graphene substrate show not only an obvious optimization in the ferroelectric behavior of P(VDF-TrFE),but also an enhancement of the charge transport within P3HT domains.By employing sandwich structure constructed by silver electrode and P3HT/P(VDF-TrFE)blend film on graphene substrate,high-performance ferroelectric memory devices have been obtained,which exhibit a great electrical switching behavior with high ON/OFF ratio of about 1000 and low coercive voltage of approximately 5 V.These findings provide useful guidance for fabricating highperformance ferroelectric memory devices.展开更多
The active layer of all polymer solar cells(all-PSCs)is composed of a blend of a p-type conjugated polymer(p-CP)as donor and an n-type conjugated polymer(n-CP)as acceptor.All-PSCs possess the advantages of light weigh...The active layer of all polymer solar cells(all-PSCs)is composed of a blend of a p-type conjugated polymer(p-CP)as donor and an n-type conjugated polymer(n-CP)as acceptor.All-PSCs possess the advantages of light weight,thin active layer,mechanical flexibility,low cost solution processing and high stability,but the power conversion efficiency(PCE)of the all-PSCs was limited by the poor photovoltaic performance of the n-CP acceptors before 2016.Since the report of the strategy of polymerized small molecule acceptors(PSMAs)in 2017,the photovoltaic performance of the PSMA-based n-CPs improved rapidly,benefitted from the development of the A-DA’D-A type small molecule acceptors(SMAs).PCE of the all-PSCs based on the PSMA acceptors reached 17%-18%recently.In this review article,we will introduce the development history of the n-CPs,especially the recent research progress of the PSMAs.Particularly,the structure-property relationship of the PSMAs is introduced and discussed.Finally,current challenges and prospects of the n-CP acceptors are analyzed and discussed.展开更多
For decades,the preparation of polyisoprene rubber that can match the comprehensive properties of natural rubber(NR)has been pursued.While sacrificial bonds have been used to promote the strength and toughness of rubb...For decades,the preparation of polyisoprene rubber that can match the comprehensive properties of natural rubber(NR)has been pursued.While sacrificial bonds have been used to promote the strength and toughness of rubbers,little is known about their effects on fatigue resistance,which is important in dynamic environments.Herein,terminal block and randomly functionalized polyisoprene rubbers tethered with di-alanine,tri-alanine and tetra-alanine were prepared.The results showed that the flow activation energy,aggregates ordering and energy dissipation of the hydrogen-bonded aggregates increase with the elongation of oligopeptide length(XA,X=2,3,4),therefore resulting in enhanced mechanical strength and toughness of corresponding samples.Comparably,the tear strengths are barely affected by oligopeptide lengths in block samples,but promoted from dipeptide to tetrapeptide in random samples,probably due to the well dispersed oligopeptide aggregates.Most importantly,it is found that the tight binding aggregates of oligopeptides are critical for the excellent fatigue resistance,which is absent in polyisoprene and natural rubber.The loose aggregates dissociate and recombine repeatedly under cyclic loading and the tight aggregates keep the network integrated and robust.Interestingly,the largest hysteresis of PIP-4A-V with the longest oligopeptide length give the lowest heat generation,which is contrary to the traditional sacrificial bonds.Overall,the oligopeptide aggregates have repeatable energy dissipation properties and cycle life comparable to or even surpassing those of the linked proteins in NR,resulting in similar tensile strength,fracture toughness,and better fatigue resistance relative to NR.This deep insight on the role of oligopeptide aggregates is very useful for the engineering rubbers served in dynamic environments.展开更多
The adsorption of aniline, N-methylaniline and N,N-dimethylaniline onto carboxyl resin in Cu2+ form from water, ethanol and n-hexane have been studied. The results show that the adsorption affinities from n-hexane are...The adsorption of aniline, N-methylaniline and N,N-dimethylaniline onto carboxyl resin in Cu2+ form from water, ethanol and n-hexane have been studied. The results show that the adsorption affinities from n-hexane are higher than that from water, and nearly zero from ethanol. The separation factors for the adsorption of these three amines from mixed solution were also examined. The results of continuous column operations show that the breakthrough capacity of aniline from n-hexane reaches 90 mg/g dry resin in Cu2+ form, and the amines adsorbed can be stripped with anhydrous ethanol effectively. Adsorption onto carboxyl resin in Cu2+ form from non-aqueous medium and desorption with anhydrous eluant can overcome the run-off of Cu2+ from the resin, and would show potential advantages in the separation of some water-insoluble natural products.展开更多
Solid polymer electrolyte films containing poly（vinyl alcohol） （PVA） and magnesium nitrate （Mg（NO3）2） were prepared by solution casting technique and characterized by using XRD, FTIR, DSC and AC impedance spec...Solid polymer electrolyte films containing poly（vinyl alcohol） （PVA） and magnesium nitrate （Mg（NO3）2） were prepared by solution casting technique and characterized by using XRD, FTIR, DSC and AC impedance spectroscopic analysis. The amorphous nature of the polymer electrolyte films has been confirmed by XRD. The complex formation between PVA and Mg salt has been confirmed by FTIR. The glass transition temperature decreases with increasing the Mg salt concentration. The AC impedance studies are performed to evaluate the ionic conductivity of the polymer electrolyte films in the range of 303-383 K, and the temperature dependence seems to obey the Arrhenius behavior. Transport number measurements show that the charge transport is mainly due to ions. Electrochemical cell of configuration Mg/（PVA ＋ Mg（NO3）2） （70：30）/（12 ＋ C ＋ electrolyte） has been fabricated. The discharge characteristics of the cell were studied for a constant load of 100 kΩ.展开更多
A new type of palladium chelate of β-diketone-based side chain liquid crystal polysiloxane (Pd-DKLCP) has been synthesized by chelation reaction of palladium dichloride with polymeric ligand, β-diketone polysiloxane...A new type of palladium chelate of β-diketone-based side chain liquid crystal polysiloxane (Pd-DKLCP) has been synthesized by chelation reaction of palladium dichloride with polymeric ligand, β-diketone polysiloxane (DKLCP), using THF as solvent at R.T.. The Pd-chelation results in greatly increasing the phase transition temperature T_K and the enthalpy change △H_K from crystal to liquid crystal state and making the temperature range of LC state △T(△T=T_(Cl)-T_K) widened. All these chelates Pd-DKLCP's do not show T_(Cl) until decomposition at 205℃. It is noteworthy that the Pd-chelation can exert more positive effect on the mesomorphic behaviour of the polymer ligand than the counterpart Cu-DKLCP does. It is probable due to the bigger size of disc-like mesogen formed from β-diketone and Pd^(+2) ion with 4d orbital.展开更多
A novel EVA/unmodified nano-magnesium hydroxide （NMH）/silicone rubber ternary nanocomposite was prepared by using a special compound flame retardant of NMH and silicone rubber （CFR）. The flammability of the ternar...A novel EVA/unmodified nano-magnesium hydroxide （NMH）/silicone rubber ternary nanocomposite was prepared by using a special compound flame retardant of NMH and silicone rubber （CFR）. The flammability of the ternary composite was studied by cone calorimeter test （CCT）. Synergistic effect on flame retardancy was found between silicone rubber and NMH. EVA/CFR ternary nanocomposite showed the lowest peak heat release rate （PHRR） and mass loss rate （MLR） among the samples of virgin EVA, EVA composites. The synergistic flame retardancy of silicone rubber and NMH in EVA system is attributed to the enhanced char layers in the condensed phase that prevents the heat and mass transfer in the fire.展开更多
The fluorescence behaviours of a new polymer poly [oxy-2 (4-N, N-dimethylaminobenzyl) propane-1 , 3-diyloxy-terephthaloyl] (Ⅰ) in solution were studied. Inter-and intra -molecular exciplex is formed between the singl...The fluorescence behaviours of a new polymer poly [oxy-2 (4-N, N-dimethylaminobenzyl) propane-1 , 3-diyloxy-terephthaloyl] (Ⅰ) in solution were studied. Inter-and intra -molecular exciplex is formed between the singlet excited state of N, N- dimethylanilino group (abbreviated to DMA) and the ground state of terephthalate group (abbreviated to TP). The intensity ratio of the long wavelength exciplex fluorescence to the short wavelength emission of DMA group is used as an index for the inter-and intra-molecular interaction of chromophores. The results are compared with model polymer polyoxy-2-(4-N ,N-dimethylaminobenzyl) propanc-1 , 3-diyloxyadipoyl (Ⅱ), model monomer compound 4-N, N-dimethylaminobenzylmethyl terephthalate(Ⅲ) and diethyl 2-( 4-N, N-dimethylaminobenzyl) malonate (Ⅳ). Polymer association derived by electron donor and acceptor interaction (EDA) is further verified as a key role in the interpolymer exciplex formation . The fluorescence decay time of (Ⅰ) and monomer (Ⅲ) are measured in solutions.展开更多
Rare earth aryloxides substituted by various alkyl groups [Ln（OAr）3] such as methyl, isopropyl and tertbutyl, were used as single component catalysts to affect ring-opening polymerization of L-lactide （LLA）. The c...Rare earth aryloxides substituted by various alkyl groups [Ln（OAr）3] such as methyl, isopropyl and tertbutyl, were used as single component catalysts to affect ring-opening polymerization of L-lactide （LLA）. The catalytic activity, polymerization characteristics, polymerization kinetics and the mechanism were studied. It was found that the catalytic activity of rare earth aryloxides is influenced by both the structure and the number of alkyl groups on the phenyl ring. The stronger the electron-donation ability of the alkyl group, the higher the catalytic activity will be. An increase in the number of the substitute group will result in a higher catalytic activity. Lanthanum tris（2,4,6-tri-tert-butylphenolate） [La（OTTBP）3] exhibits the highest activity among all lanthanum aryloxides. According to the ^1H-NMR data, it was proposed that the LLA polymerization proceeded via a coordination-insertion mechanism involving cleavage of acyl-oxygen bond of the laetide.展开更多
A new type of selenious polymer, silica-bound polybispropoxyethyl-selenidesilsesquinoxane, and its platinum complex were synthesized from bis-allyloxyethyl selenide via hydrosilylation with triethoxysilane, followed b...A new type of selenious polymer, silica-bound polybispropoxyethyl-selenidesilsesquinoxane, and its platinum complex were synthesized from bis-allyloxyethyl selenide via hydrosilylation with triethoxysilane, followed by immobilized on fumed silica, and then reacting with potassium chloroplatinite under nitrogen atmosphere in acetone. It was found that the platinum complex can catalyze the hydrosilylation of olefins with triethoxysilane effectively. The effects of the nature of the substrate, the amount of complex used, and the reaction temperature on the catalytic activity were investigated.展开更多
When the size of the material is smaller than the size of the molecular chain,new nanostructures can be formed by crystallizing polymers in nanoporous alumina.However,the effect of pore wall and geometric constraints ...When the size of the material is smaller than the size of the molecular chain,new nanostructures can be formed by crystallizing polymers in nanoporous alumina.However,the effect of pore wall and geometric constraints on polymer nanostructures remains unclear.In this study,we demonstrate three new restricted nanostructures{upright-,flat-and tilting-ring}in polybutylene terephthalate(PBT)nanorods prepared from nanoporous alumina.The dual effects of geometrical constraints and interfacial interactions on the formation of PBT nanostructures were investigated for the first time by using X-ray diffraction and Cerius^(2) modeling packages.Under weak constraints,the interaction between pore wall and the PBT rings is dominant and the ring plane tends to be parallel to the pore wall and radiate outward to grow the upright-ring crystals.Surprisingly,in strong 2D confinement,a structural formation reversal occurs and geometrical constraints overpower the effect of pore wall.Rings tend to pile up vertically or obliquely along the long axis of the rod,so the flat-and tilting-ring crystals are predominate in the constrained system.In principle,our study of the nanostructure formation based on the geometrical constraints and the pore wall interfacial effects could provide a new route to manipulate the chain assembly at the nanoscale,further improving the performance of polymer nanomaterial.展开更多
The recent progress in the design and synthesis of high-performance donor-acceptor conjugated polymeric semiconducting materials is reviewed from the perspective of multiscale structures.The multiscale of conjugated p...The recent progress in the design and synthesis of high-performance donor-acceptor conjugated polymeric semiconducting materials is reviewed from the perspective of multiscale structures.The multiscale of conjugated polymers is from the primary one-dimensional polymer molecular scale to the secondary polymer-chains interaction scale,and then to the tertiary polymer aggregate scale.This review focuses on the design and synthesis of polymer molecules,proposes new classification rules,and rationally summarizes the design strategies and modulation methods of polymers.We describe the recent progress from these three aspects:(1)the modification ofπ-conjugated backbone,(2)the evolution of the polymerization methods,and(3)the regulation of aggregate-state structure.展开更多
Thermoplastic polyimides(PIs)with shape memory potential have received growing attention in recent years.In this work,highperformance thermoplastic PIs were fabricated by introducing PIs with chain rigidity(r-PI)into ...Thermoplastic polyimides(PIs)with shape memory potential have received growing attention in recent years.In this work,highperformance thermoplastic PIs were fabricated by introducing PIs with chain rigidity(r-PI)into PI with chain flexibility(f-PI).The influences of molecular chain entanglement andπ-πinteractions on their thermomechanical and shape memory properties were investigated.The degree of molecular chain entanglement was quantitively characterized based on dynamic mechanical analysis(DMA).Theπ-πinteractions were investigated in detail by X-ray diffraction(XRD)and UV-Vis spectroscopy.It was found that the entanglement density increased andπ-πinteractions became stronger with the introduction of r-PI into f-PI,leading to the improvement of shape recovery.Moreover,a broad and increased glass transition temperature(T_(g))was achieved,endowing the PIs with multiple shape memory properties.The synergistic effects of increased entanglement density and enhancedπ-πinteractions were beneficial to regulating interchain interactions and thereby achieving high shape memory performance of the PIs.展开更多
Atom transfer radical polymerization (ATRP) of styrene catalyzed by cuprous (CuX)/1,10-phenanthroline (Phen) and CuX/CuX2/Phen was conducted in an aqueous dispersed system. A stable latex was obtained by using ionic s...Atom transfer radical polymerization (ATRP) of styrene catalyzed by cuprous (CuX)/1,10-phenanthroline (Phen) and CuX/CuX2/Phen was conducted in an aqueous dispersed system. A stable latex was obtained by using ionic surfactant sodium lauryl sulfonate (SLS) or composite surfactants, such as SLS/polyoxyethylene nonyl phenyl ether (OP-10), SLS/hexadecanol and SLS/OP-10/hexadecanol, Among which SLS and SLS/OP-10/hexadecanol systems established better dispersed effect during the polymerization, It was found that Phen was a more suitable ligand than N,N,N',N',N'-pentamethyldiethylenetriamine (PMDETA) to maintain an appropriate equilibrium of the activator Cu(I) and the deactivator Cu(II) between the organic phase and the water phase, The effect of several initiators (such as EBiB, CCl4 and 1-PEBr) and the temperature on such a kind of ATRP system was also observed. The number-average molar mass (M-n) of polystyrene (PS) increased with the conversion and the molar mass distribution (M-w/M-n) remained narrow. These experimental data show that the polymerization could be controlled except for the quick increase of monomer conversion and the number-average molar mass of PS in the initial stage of polymerization. Furthermore, the initiator efficiency was found to be low (similar to57%) in CuX/Phen catalyzed system. To overcome this problem, Cu(II)X-2 (20 mol%-50 mol% based on CuX) was introduced into the polymerization system. In this case, higher initiator efficiency (60%-90%), low M-w/M-n of PS (as low as 1.08) were achieved and the molar masses of the PS fit with the theoretical ones.展开更多
Renyuan Qian was born on September 19, 1917 in Changshu, Jiangsu province.He graduated from the Chemistry Department of Zhejiang University in 1939. Inthe year of 1943, he went to the United States to take postgraduat...Renyuan Qian was born on September 19, 1917 in Changshu, Jiangsu province.He graduated from the Chemistry Department of Zhejiang University in 1939. Inthe year of 1943, he went to the United States to take postgraduate studies mainlyin the University of Wisconsin. In 1948, he returned to China and associated with Xiamen University and Zhe-展开更多
The investigation of electrochromic effect of corona-poled nonlinear optical polymer films is an effective method for the estimation of poling level and the selection of poling conditions. The poling electric field E_...The investigation of electrochromic effect of corona-poled nonlinear optical polymer films is an effective method for the estimation of poling level and the selection of poling conditions. The poling electric field E_p and orientational order parameter Φ, which are the important parameters to predict d_(33) of poled films, can be calculated by a simple operation from the number of red shift of charge transfer absorption band. The calculated results are in good agreement with the experimental data.展开更多
基金This work was supported by the National Key Projects for Fundamental Research, "Macromolecular Condensed State" of Ministry of Science and Technology of China.
文摘The kinetics of I-->N transition of a side chain nematic polymethacrylate has been studied by small angle depolarized light scattering intensity measurements using a charge coupled device linear image sensor. The polymer shows the transition temperatures K52N79I in degreesC, The H-v scattering intensity T(q,t) during the transition I (at 80.2degreesC)-->N (at 75.8degreesC) shows that T(q) is independent of q for all t, and during the initial stage (in 6 s) T(t) increases exponentially with t. In the later stage of the transition T(t) approaches a saturation value in 2 min. This experimental result indicates that the I-->N transition of a liquid crystalline polymer is a spinodal type of phase transition mediated by orientation fluctuation.
基金This project was supported by the National Natural Science Foundation of China (No. 59803006), the Major State Basic Research Program of China (G1999054305) and the Natural Science Foundation of Zhejiang Province.
文摘Two grafting methods, i.e. solution grafting and pre-adsorbing, are introduced to covalently immobilizehydrophilic polymers on segmented polyurethane (SPU) to modify its hydrophilicity and to improve its cell compatibility.Solution grafting results in higher degree of grafting and rougher surface morphology. Cell culture evaluation demonstratesthat the modified membranes thus obtained are disadvantageous to the endothelial cell (ECs) growth probably because thehydrophilic groups on the surface are over-crowded. However, pre-absorbing grafting generates lower degree of grafting,which is detected and confirmed by ATR-FTIR spectra and water conted angle. Scanning electron microscopic (SEM)measurement shows that the latter method produces a plane and smooth morphology, which is similar to the SPU controlsample controlled. When grafting with lower monomer concentration, ECs could grow on SPU-g-PHEA [poly(2-hydroxyethyl acrylate)], SPU-g-PAAm (polyacrylamide), SPU-g-PDMA [poly(2-(dimethylamino)ethyl methacrylate)] orquatemized SPU-g-PDMA surface with elongated cell shapes. Hence, the cell compatibility of SPU is improved and a usefulmethod to construct a cell compatible layer on the polymer surface has been developed.
基金supported by the National Natural Science Foundation of China (No. 50903004)
文摘In this study, a novel H-bonded cholesteric polymer film responding to temperature and pH by changing the reflection color was fabricated. The H-bonded cholesteric polymer film was achieved by UV-photopolymerizing a cholesteric liquid crystal （Ch-LC） monomers mixture containing a photopolymerizable chiral H-bonded assembly （PCHA）. The cholesteric polymer film based on PCHA can be thermally switched to reflect red color from the initial green/yellow color as temperature is increased, which is due to a change in helical pitch induced by the weakening of H-bonded interaction in the polymer film. Additionally, the selective reflection band （SRB） of the cholesteric polymer film in solution with pH 〉 7 showed an obvious red shift with increasing pH values. While the SRB of the cholesteric polymer film in solutions with pH = 7 and pH 〈 7 hardly changed. This pH sensitivity in solutions with pH 〉 7 could be explained by the breakage of H-bonds in the cholesteric polymer film and the structure changes induced by --OH- and --K＋ ions in the alkaline solution. In contrast, it couldn＇t happen in the neutral and acidic solutions. The cholesteric polymer film in this study can be used as optical/photonic papers, optical sensors and LCs displays, etc.
基金This project supported by the National Natural Science Foundation of China.
文摘Polymerization of acrylonitrile (AN) in aqueous nitric acid initiated by polypropylene-based polyamidoxime (PPAO)-thiourea (TU) combination has been investigated. The overall rate of polymerization (R_p) under the conditions of [TU]/[PPAO]<0.5 molar ratio isThe molecular weights of the polymers were found to be inversely proportional to 3/2-power of nitric acid concentration and 1-power of thiourea concentration. In addition, it is independent with the concentrations of monomer and PPAO, and decreases with increasing temperature.On the basis of these experimental results, a coordination-proton transfer mechanism for the initiation was proposed and discussed.
基金financially supported by the National Natural Science Foundation of China(Nos.21774011,22022501 and 22073006).
文摘Ferroelectric poly(vinylidene fluoride-trifluoroethylene)(P(VDF-TrFE))/semiconducting poly(3-hexyl thiophene)(P3HT)blend systems have drawn great attention with their potential use for electronic applications,particularly non-volatile memory devices.It is essential to grasp a full understanding of the crystallization habits of the two polymers on different substrates for purposeful control of the structures of the blend and therefore the properties of the devices.Here,the effects of structure and morphology of the blend films generated at different substrate surfaces on the ferroelectric and switching properties of related devices are reported.It is identified that P(VDF-TrFE)/P3HT blend films prepared on graphene substrate show not only an obvious optimization in the ferroelectric behavior of P(VDF-TrFE),but also an enhancement of the charge transport within P3HT domains.By employing sandwich structure constructed by silver electrode and P3HT/P(VDF-TrFE)blend film on graphene substrate,high-performance ferroelectric memory devices have been obtained,which exhibit a great electrical switching behavior with high ON/OFF ratio of about 1000 and low coercive voltage of approximately 5 V.These findings provide useful guidance for fabricating highperformance ferroelectric memory devices.
基金financially supported by the National Natural Science Foundation of China(Nos.61904181,51820105003,52173188 and 21734008)the Basic and Applied Basic Research Major Program of Guangdong Province(No.2019B030302007)。
文摘The active layer of all polymer solar cells(all-PSCs)is composed of a blend of a p-type conjugated polymer(p-CP)as donor and an n-type conjugated polymer(n-CP)as acceptor.All-PSCs possess the advantages of light weight,thin active layer,mechanical flexibility,low cost solution processing and high stability,but the power conversion efficiency(PCE)of the all-PSCs was limited by the poor photovoltaic performance of the n-CP acceptors before 2016.Since the report of the strategy of polymerized small molecule acceptors(PSMAs)in 2017,the photovoltaic performance of the PSMA-based n-CPs improved rapidly,benefitted from the development of the A-DA’D-A type small molecule acceptors(SMAs).PCE of the all-PSCs based on the PSMA acceptors reached 17%-18%recently.In this review article,we will introduce the development history of the n-CPs,especially the recent research progress of the PSMAs.Particularly,the structure-property relationship of the PSMAs is introduced and discussed.Finally,current challenges and prospects of the n-CP acceptors are analyzed and discussed.
基金financially supported by the National Natural Science Foundation of China(No.51973126)the State Key Laboratory of Polymer Materials Engineering(No.sklpme20222-11)。
文摘For decades,the preparation of polyisoprene rubber that can match the comprehensive properties of natural rubber(NR)has been pursued.While sacrificial bonds have been used to promote the strength and toughness of rubbers,little is known about their effects on fatigue resistance,which is important in dynamic environments.Herein,terminal block and randomly functionalized polyisoprene rubbers tethered with di-alanine,tri-alanine and tetra-alanine were prepared.The results showed that the flow activation energy,aggregates ordering and energy dissipation of the hydrogen-bonded aggregates increase with the elongation of oligopeptide length(XA,X=2,3,4),therefore resulting in enhanced mechanical strength and toughness of corresponding samples.Comparably,the tear strengths are barely affected by oligopeptide lengths in block samples,but promoted from dipeptide to tetrapeptide in random samples,probably due to the well dispersed oligopeptide aggregates.Most importantly,it is found that the tight binding aggregates of oligopeptides are critical for the excellent fatigue resistance,which is absent in polyisoprene and natural rubber.The loose aggregates dissociate and recombine repeatedly under cyclic loading and the tight aggregates keep the network integrated and robust.Interestingly,the largest hysteresis of PIP-4A-V with the longest oligopeptide length give the lowest heat generation,which is contrary to the traditional sacrificial bonds.Overall,the oligopeptide aggregates have repeatable energy dissipation properties and cycle life comparable to or even surpassing those of the linked proteins in NR,resulting in similar tensile strength,fracture toughness,and better fatigue resistance relative to NR.This deep insight on the role of oligopeptide aggregates is very useful for the engineering rubbers served in dynamic environments.
基金This study was supported by National Natural Science Foundation (Grant No. 29974015)
文摘The adsorption of aniline, N-methylaniline and N,N-dimethylaniline onto carboxyl resin in Cu2+ form from water, ethanol and n-hexane have been studied. The results show that the adsorption affinities from n-hexane are higher than that from water, and nearly zero from ethanol. The separation factors for the adsorption of these three amines from mixed solution were also examined. The results of continuous column operations show that the breakthrough capacity of aniline from n-hexane reaches 90 mg/g dry resin in Cu2+ form, and the amines adsorbed can be stripped with anhydrous ethanol effectively. Adsorption onto carboxyl resin in Cu2+ form from non-aqueous medium and desorption with anhydrous eluant can overcome the run-off of Cu2+ from the resin, and would show potential advantages in the separation of some water-insoluble natural products.
文摘Solid polymer electrolyte films containing poly（vinyl alcohol） （PVA） and magnesium nitrate （Mg（NO3）2） were prepared by solution casting technique and characterized by using XRD, FTIR, DSC and AC impedance spectroscopic analysis. The amorphous nature of the polymer electrolyte films has been confirmed by XRD. The complex formation between PVA and Mg salt has been confirmed by FTIR. The glass transition temperature decreases with increasing the Mg salt concentration. The AC impedance studies are performed to evaluate the ionic conductivity of the polymer electrolyte films in the range of 303-383 K, and the temperature dependence seems to obey the Arrhenius behavior. Transport number measurements show that the charge transport is mainly due to ions. Electrochemical cell of configuration Mg/（PVA ＋ Mg（NO3）2） （70：30）/（12 ＋ C ＋ electrolyte） has been fabricated. The discharge characteristics of the cell were studied for a constant load of 100 kΩ.
文摘A new type of palladium chelate of β-diketone-based side chain liquid crystal polysiloxane (Pd-DKLCP) has been synthesized by chelation reaction of palladium dichloride with polymeric ligand, β-diketone polysiloxane (DKLCP), using THF as solvent at R.T.. The Pd-chelation results in greatly increasing the phase transition temperature T_K and the enthalpy change △H_K from crystal to liquid crystal state and making the temperature range of LC state △T(△T=T_(Cl)-T_K) widened. All these chelates Pd-DKLCP's do not show T_(Cl) until decomposition at 205℃. It is noteworthy that the Pd-chelation can exert more positive effect on the mesomorphic behaviour of the polymer ligand than the counterpart Cu-DKLCP does. It is probable due to the bigger size of disc-like mesogen formed from β-diketone and Pd^(+2) ion with 4d orbital.
基金This work was subsidized by the Special Funds for Major State Basic Research Projects(No.2005CB623800).
文摘A novel EVA/unmodified nano-magnesium hydroxide （NMH）/silicone rubber ternary nanocomposite was prepared by using a special compound flame retardant of NMH and silicone rubber （CFR）. The flammability of the ternary composite was studied by cone calorimeter test （CCT）. Synergistic effect on flame retardancy was found between silicone rubber and NMH. EVA/CFR ternary nanocomposite showed the lowest peak heat release rate （PHRR） and mass loss rate （MLR） among the samples of virgin EVA, EVA composites. The synergistic flame retardancy of silicone rubber and NMH in EVA system is attributed to the enhanced char layers in the condensed phase that prevents the heat and mass transfer in the fire.
文摘The fluorescence behaviours of a new polymer poly [oxy-2 (4-N, N-dimethylaminobenzyl) propane-1 , 3-diyloxy-terephthaloyl] (Ⅰ) in solution were studied. Inter-and intra -molecular exciplex is formed between the singlet excited state of N, N- dimethylanilino group (abbreviated to DMA) and the ground state of terephthalate group (abbreviated to TP). The intensity ratio of the long wavelength exciplex fluorescence to the short wavelength emission of DMA group is used as an index for the inter-and intra-molecular interaction of chromophores. The results are compared with model polymer polyoxy-2-(4-N ,N-dimethylaminobenzyl) propanc-1 , 3-diyloxyadipoyl (Ⅱ), model monomer compound 4-N, N-dimethylaminobenzylmethyl terephthalate(Ⅲ) and diethyl 2-( 4-N, N-dimethylaminobenzyl) malonate (Ⅳ). Polymer association derived by electron donor and acceptor interaction (EDA) is further verified as a key role in the interpolymer exciplex formation . The fluorescence decay time of (Ⅰ) and monomer (Ⅲ) are measured in solutions.
基金supported by the Natural Science Foundation of Shanxi Province(No.2006011069)the Opening Foundation of Key Laboratory of Shanxi Province(No.2009011059-7)
文摘Rare earth aryloxides substituted by various alkyl groups [Ln（OAr）3] such as methyl, isopropyl and tertbutyl, were used as single component catalysts to affect ring-opening polymerization of L-lactide （LLA）. The catalytic activity, polymerization characteristics, polymerization kinetics and the mechanism were studied. It was found that the catalytic activity of rare earth aryloxides is influenced by both the structure and the number of alkyl groups on the phenyl ring. The stronger the electron-donation ability of the alkyl group, the higher the catalytic activity will be. An increase in the number of the substitute group will result in a higher catalytic activity. Lanthanum tris（2,4,6-tri-tert-butylphenolate） [La（OTTBP）3] exhibits the highest activity among all lanthanum aryloxides. According to the ^1H-NMR data, it was proposed that the LLA polymerization proceeded via a coordination-insertion mechanism involving cleavage of acyl-oxygen bond of the laetide.
文摘A new type of selenious polymer, silica-bound polybispropoxyethyl-selenidesilsesquinoxane, and its platinum complex were synthesized from bis-allyloxyethyl selenide via hydrosilylation with triethoxysilane, followed by immobilized on fumed silica, and then reacting with potassium chloroplatinite under nitrogen atmosphere in acetone. It was found that the platinum complex can catalyze the hydrosilylation of olefins with triethoxysilane effectively. The effects of the nature of the substrate, the amount of complex used, and the reaction temperature on the catalytic activity were investigated.
基金financially supported by Natural Science Foundation of Shenzhen University(Nos.827-000150 and 860-000002110375).
文摘When the size of the material is smaller than the size of the molecular chain,new nanostructures can be formed by crystallizing polymers in nanoporous alumina.However,the effect of pore wall and geometric constraints on polymer nanostructures remains unclear.In this study,we demonstrate three new restricted nanostructures{upright-,flat-and tilting-ring}in polybutylene terephthalate(PBT)nanorods prepared from nanoporous alumina.The dual effects of geometrical constraints and interfacial interactions on the formation of PBT nanostructures were investigated for the first time by using X-ray diffraction and Cerius^(2) modeling packages.Under weak constraints,the interaction between pore wall and the PBT rings is dominant and the ring plane tends to be parallel to the pore wall and radiate outward to grow the upright-ring crystals.Surprisingly,in strong 2D confinement,a structural formation reversal occurs and geometrical constraints overpower the effect of pore wall.Rings tend to pile up vertically or obliquely along the long axis of the rod,so the flat-and tilting-ring crystals are predominate in the constrained system.In principle,our study of the nanostructure formation based on the geometrical constraints and the pore wall interfacial effects could provide a new route to manipulate the chain assembly at the nanoscale,further improving the performance of polymer nanomaterial.
基金financially supported by the National Key R&D Program of‘Key Scientific Issues of Transformative Technology’(No.2018YFA0703200)the National Natural Science Foundation of China(Nos.U22A6002,91833306,21922511 and 51873216)+4 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB30000000)the CAS Project for Young Scientists in Basic Research(No.YSBR-053)the CAS-Croucher Funding Scheme for Joint Laboratoriesthe CAS Cooperation Project(No.121111KYSB20200036)the Lu Jiaxi international team(No.GJTD-2020-02)。
文摘The recent progress in the design and synthesis of high-performance donor-acceptor conjugated polymeric semiconducting materials is reviewed from the perspective of multiscale structures.The multiscale of conjugated polymers is from the primary one-dimensional polymer molecular scale to the secondary polymer-chains interaction scale,and then to the tertiary polymer aggregate scale.This review focuses on the design and synthesis of polymer molecules,proposes new classification rules,and rationally summarizes the design strategies and modulation methods of polymers.We describe the recent progress from these three aspects:(1)the modification ofπ-conjugated backbone,(2)the evolution of the polymerization methods,and(3)the regulation of aggregate-state structure.
基金financially supported by the Engineering Research Center for Clean Production of Textile Printing and Dyeing,Ministry of Education(No.FZYR2021001)Shanghai Pujiang Program(No.19PJ1400400)Shanghai Key Laboratory of Lightweight Composite(No.2232019A4-04)。
文摘Thermoplastic polyimides(PIs)with shape memory potential have received growing attention in recent years.In this work,highperformance thermoplastic PIs were fabricated by introducing PIs with chain rigidity(r-PI)into PI with chain flexibility(f-PI).The influences of molecular chain entanglement andπ-πinteractions on their thermomechanical and shape memory properties were investigated.The degree of molecular chain entanglement was quantitively characterized based on dynamic mechanical analysis(DMA).Theπ-πinteractions were investigated in detail by X-ray diffraction(XRD)and UV-Vis spectroscopy.It was found that the entanglement density increased andπ-πinteractions became stronger with the introduction of r-PI into f-PI,leading to the improvement of shape recovery.Moreover,a broad and increased glass transition temperature(T_(g))was achieved,endowing the PIs with multiple shape memory properties.The synergistic effects of increased entanglement density and enhancedπ-πinteractions were beneficial to regulating interchain interactions and thereby achieving high shape memory performance of the PIs.
文摘Atom transfer radical polymerization (ATRP) of styrene catalyzed by cuprous (CuX)/1,10-phenanthroline (Phen) and CuX/CuX2/Phen was conducted in an aqueous dispersed system. A stable latex was obtained by using ionic surfactant sodium lauryl sulfonate (SLS) or composite surfactants, such as SLS/polyoxyethylene nonyl phenyl ether (OP-10), SLS/hexadecanol and SLS/OP-10/hexadecanol, Among which SLS and SLS/OP-10/hexadecanol systems established better dispersed effect during the polymerization, It was found that Phen was a more suitable ligand than N,N,N',N',N'-pentamethyldiethylenetriamine (PMDETA) to maintain an appropriate equilibrium of the activator Cu(I) and the deactivator Cu(II) between the organic phase and the water phase, The effect of several initiators (such as EBiB, CCl4 and 1-PEBr) and the temperature on such a kind of ATRP system was also observed. The number-average molar mass (M-n) of polystyrene (PS) increased with the conversion and the molar mass distribution (M-w/M-n) remained narrow. These experimental data show that the polymerization could be controlled except for the quick increase of monomer conversion and the number-average molar mass of PS in the initial stage of polymerization. Furthermore, the initiator efficiency was found to be low (similar to57%) in CuX/Phen catalyzed system. To overcome this problem, Cu(II)X-2 (20 mol%-50 mol% based on CuX) was introduced into the polymerization system. In this case, higher initiator efficiency (60%-90%), low M-w/M-n of PS (as low as 1.08) were achieved and the molar masses of the PS fit with the theoretical ones.
文摘Renyuan Qian was born on September 19, 1917 in Changshu, Jiangsu province.He graduated from the Chemistry Department of Zhejiang University in 1939. Inthe year of 1943, he went to the United States to take postgraduate studies mainlyin the University of Wisconsin. In 1948, he returned to China and associated with Xiamen University and Zhe-
文摘The investigation of electrochromic effect of corona-poled nonlinear optical polymer films is an effective method for the estimation of poling level and the selection of poling conditions. The poling electric field E_p and orientational order parameter Φ, which are the important parameters to predict d_(33) of poled films, can be calculated by a simple operation from the number of red shift of charge transfer absorption band. The calculated results are in good agreement with the experimental data.
