High-performance and robust high-temperature polymer electrolyte membranes with moderate microphase separation by implementation of terphenyl-based polymers

Acid loss and plasticization of phosphoric acid(PA)-doped high-temperature polymer electrolyte membranes(HT-PEMs)are critical limitations to their practical application in fuel cells.To overcome these barriers,poly(terphenyl piperidinium)s constructed from the m-and p-isomers of terphenyl were synthesized to regulate the microstructure of the membrane.Highly rigid p-terphenyl units prompt the formation of moderate PA aggregates,where the ion-pair interaction between piperidinium and biphosphate is reinforced,leading to a reduction in the plasticizing effect.As a result,there are trade-offs between the proton conductivity,mechanical strength,and PA retention of the membranes with varied m/p-isomer ratios.The designed PA-doped PTP-20m membrane exhibits superior ionic conductivity,good mechanical strength,and excellent PA retention over a wide range of temperature(80–160°C)as well as satisfactory resistance to harsh accelerated aging tests.As a result,the membrane presents a desirable combination of performance(1.462 W cm^(-2) under the H_(2)/O_(2)condition,which is 1.5 times higher than that of PBI-based membrane)and durability(300 h at 160°C and 0.2 A cm^(-2))in the fuel cell.The results of this study provide new insights that will guide molecular design from the perspective of microstructure to improve the performance and robustness of HT-PEMs.

Microphase Separation of Star-diblock Copolymer Films： a Dissipative Particle Dynamics Simulation

The microphase-separating behaviors of two types of star-diblock copolymers （Ax）4（By）4 and （A^Bg）4 in thin films are studied using the simulation technique of dissipative particle dynamics. A variety of ordered mesostructures have been observed and the simulated phase diagrams show obvious symmetries for the （Ax）4（By）a films and asymmetries for the （AxBy）4 films, besides, it is easier for the （Ax）4（By）4 than for the （A^By）4 to carry out microphase separation under the same conditions, which has been recognized in bulk and can be ascribed to the structural difference between the two types of star copolymers. There are some correspondences between the mesostructures formed in the film and those formed in bulk at the same composition fraction. Decreasing the thickness of film and strengthening the A-B repulsion both help the mesostructures enhance the degree of order. Composition fraction dependences of the mean-square radius of gyration in the two types of star copolymer films are almost contrary, which can be attributed to the differences in their respective structures. These findings can provide a guide to designing novel microstructures involving star-diblock copolymers via geometrical confinement.

SYNTHESIS AND CHARACTERIZATION OF AMPHIPHILIC GRAFT COPOLYMER CONTAINING MICROPHASE SEPARATED AND LONG POLY(ETHYLENE OXIDE) SIDE CHAIN STRUCTURES

Acryloyl terminated Poly (ethyleneoxide)macromonomers (PEO-A) with different PEO chain lengths have been prepared by deactivation of PEO alkoxide with acryloyl chloride. A new kind of amphiphilic polystyrene-g-poly (ethylene oxide)graft copolymer containing both microphase separated and PEO side chain structures has been synthesized from radical copolymerization of PEO-A macromonomer with styrene. After careful purification by a newly-developed method called 'selective dissolution', the well-defined structure of the purified copolymers was confirmed by IR, ~1H-NMR and GPC. Various experimental parameters controlling the copolymerization were studied in detail. The results indicated that the feed ratio of styrene to macromonomer(S/M) was the most important determining factor for the composition of the copolymers. A detailed 'comb- model' was proposed to describe the molecular structure of the graft copolymers. Finally, this amphiphilic graft copolymers may readily form microphase separated structures as clearly indicated by transmission electron microscopy.

MICROPHASE SEPARATED STRUCTURES AND PROPERTIES OF PDMS-MDIPEG COPOLYMER SURFACE

A series of poly(dimethylsiloxane)(PDMS)-4,4′-diphenylmethanediisocyanate(MDI)-poly(ethylene glycol)(PEG) multiblock copolymers were synthesized by employing two-step growth polymerization and investigated by AFM,XPS. contact angle system,protein adsorption and platelets adhesion measurements,respectively.It was found that as the molecular weight of PDMS increased,the surface of copolymers had increasing phase separation,while the increase in the molecular weight of PEG decreased the phase separation extents of the copolymer surface.XPS and contact angle measurements showed that the greater the phase separation extent was,the lower both the surface enrichment of PDMS and the surface free energy of the copolymer film were.The protein adsorption experiments indicated that the best phase separation did not exhibit the best biocompatibility.

ORDERED STRUCTURAL EVOLUTION AND RELAXATION BEHAVIORS OF A SERIES MICROPHASE SEPARATED“HAIRY-ROD”POLYIMIDES WITH MULTIPLE ALKYL SIDE CHAINS

A series of“hairy-rod”polyimides,BBPA(n),with multiple alkyl side chains was prepared from 3,3',4,4'-biphenyltetracarboxylic dianhydride(BPDA)and 4,4'-biphenyldiamine substituted in the 2,2'-positions with benzoate,whichwas substituted in the 3,4,5-positions with ether side chains of varying lengths.The number of the methylene units,n,inthese alkyl side chains were in even numbers ranging from 8 to 18.Combining techniques of one-dimensional(1D)and 2Dwide angle x-ray diffraction,1D small angle X-ray scattering,differential scanning calorimetry experiments,it was found thatthis series of“hairy-rod”polyimides possess a micro-phase separation between the backbones and side chains.This led to theformation of ordered structures in two different length scales,of which both are hexagonal packing:one is attributed to thealkyl side chains on the sub-nanometer scale,and another is for the whole polymer chains on the nanometer scale.Thedevelopment of the hexagonal structure on the sub-nanometer scale was critically dependent upon the lengths of the alkylside chains.Three relaxation processes were captured by dynamic mechanical analysis,i.e.,segmental motion of thebackbones,α,the melting of the side chain crystals,β_1,which exits only for the materials with longer side chains(n=18,16);and the subglass relaxation of side chains,β_2.The peak relaxation temperature of the α process decreased withincreasing the length of side chains,while the one of the β_2 process increased.The activation energy of the α relaxation wasrelatively independent on the length of side chain,whereas,β_2 process showed the increasing of activation energy withincreasing the length of side chains.

Synthesis, Purification and Characterization of Amphiphilic and Microphase Separated Graft Copolymer Polystyrene-g-Poly(ethylene oxide)

The present paper covers the poly (ethylene oxide) macromer with vinyl benzyl terminal group (PEO-VB) prepared by deactivation of the alkoxide function of mono-functional 'living' PEO chains with vinyl benzyl chloride (VBC). The obtained macromers were subjected to careful purification and detailed characterization. A new kind of amphiphilic polystyrene-g-poly(ethylene oxide) (PS-g-PEO) with both mi-crophase separated and PEO side chains was synthesized from radical copolymerization of PEO-VB macromer with styrene monomer. An improved purification method, referred as 'selective dissolvation', was established for the isolation of graft copolymers from the grafting products, and the purity and yield of the purified copolymers were satisfactory. The well-defined structure of the purified copolymers was confirmed by IR, 1H NMR and GPC. The bulk composition of the graft copolymers was determined by a well-established first derivative UV spectrometry. Various experimental parameters controlling the copolymerization were also studied. The results indicate that the feed ratio of macromer to styrene (M/S) was the most important factor in determining the composition of the copolymers. Thus a series of PS-g-PEO with a wide range of bulk compositions were obtained simply by adjusting the value of M/S. As clearly indicated by transmission electron microscopy, this amphiphilic graft copolymers may readily form microphase separated structures.

THE ROLES OF REACTION INHOMOGENEITY IN PHASE SEPARATION KINETICS AND MORPHOLOGY OF REACTIVE POLYMER BLENDS

The roles of reaction inhomogeneity in phase separation of polymer mixtures were described and summarized via two examples:photocross-link of polymer mixtures in the bulk state and photopolymerization of monomer in the liquid state. The reaction kinetics,the reaction-induced elastic strain and the phase separation kinetics were monitored respectively by UV-Vis spectroscopy,Mach-Zehnder interferometry and laser-scanning confocal microscopy.It was found that phase separation in the bulk state was strongly inf...

微相分离型聚丙烯热塑性弹性体的力学性能

为了制备相畴尺寸均匀、细小,形态结构易控,力学性能稳定的聚丙烯热塑性弹性体(PTPE),设计出了从聚丙烯(PP)与弹性体的均相体系出发,利用在硫化过程中的能效应使之发生微相分离,能效应和熵效应控制组分相畴的尺寸和形态以制备PTPE的原理和技术,研究了橡/塑比、橡胶配比、PP相对分子质量、引发剂用量、架桥剂用量、反应温度对样品化学结构和力学性能的影响。结果表明,在125℃反应温度下样品配方为:橡塑质量比为70/30、乙丙橡胶与丁苯质量比为80∶20、引发剂用量为2.14份、架桥剂用量为18.2份时,制得试样的综合力学性能最佳,拉伸强度、100%定伸应力、扯断伸长率、撕裂强度、扯断永久变形分别为11.25 MPa、8.78 MPa、384%、58.5 kN/m、78%。

基于含亚胺键香草醛二醇的生物基可降解热塑性聚氨酯的制备及性能

由于资源稀缺和环境保护要求,依赖于石化来源的传统热塑性聚氨酯(TPU)在工业生产可持续性和使用后的废物的回收方面都面临着重大挑战。开发由可再生生物质资源合成的生物基TPU正变得日益迫切。以可再生的生物质资源香草醛(VAN)与间苯二甲胺反应合成了分子结构中带亚胺键的生物基扩链剂VAN衍生二醇(VAN-OH),并与1,4-丁二醇(BDO)组成不同比例的扩链剂组分,通过两步法与聚己内酯二醇(PCL),4,4′-二苯基甲烷二异氰酸酯(MDI)加成聚合制备了一种高性能、可降解的生物基热塑性聚氨酯(BTPUs)。对BTPUs的结构、热性能、力学性能及化学降解性能进行了测试与表征。结果表明,适量生物基扩链剂VAN-OH的加入增强了BTPUs分子链结构中氢键作用、结晶性能和微相分离程度,从而提高了BTPUs的热稳定性、力学性能及降解性能。当VAN-OH在扩链剂中的物质的量分数为25%时,BTPUs的力学性能表现最佳,拉伸强度为33.32 MPa,断裂伸长率为823.62%,降解时间相较于未加VAN-OH的缩短了37.5%。当VAN-OH在扩链剂中的物质的量分数超过50%时,BTPUs的力学性能下降明显,但降解时间进一步缩短。上述研究结果验证了含动态亚胺键生物基扩链剂的存在能改善TPU的热学、力学与降解性能,可为开发新型BTPUs提供借鉴。

PTMG分子量对TPU微相分离结构和力学性能的影响

以聚四亚甲基醚二醇、4,4′-二苯基甲烷二异氰酸酯和1,4-丁二醇为原料制备了3种软段分子量不同的聚醚基聚氨酯,研究了软段分子量对热塑性聚氨酯的微观结构和宏观性能的影响。采用红外光谱和小角X射线散射表征了材料的氢键作用和相结构;采用差示扫描量热法、动态热机械分析和拉伸物理方法表征了材料的热性能和力学性能;结合耗散粒子动力学(DPD)模拟,从另一方面说明了3种热塑性聚氨酯材料的相结构。结果表明,随着所用聚醚分子量的增加,聚氨酯的微相分离程度增加,硬段之间的氢键作用更强,链段紧密排列聚集形成大尺寸的硬段相区;高分子量聚醚基聚氨酯的力学性能表现最好,具有更高的熔点,与模拟结果保持一致。

羟基硅油增强反应性聚氨酯涂层的制备及其性能

为改善聚氨酯(PU)材料的力学性能,以聚四氢呋喃醚二醇、蓖麻油、双羟基封端聚二甲基硅氧烷(PDMS)为软段,二苯基甲烷二异氰酸酯(MDI)为硬段,采用绿色环保的无溶剂体系制备了有机硅改性的反应性聚氨酯(Si-PU)涂层,考察了PDMS质量分数对PU涂层的拉伸强度、断裂伸长率、高温热稳定性、耐低温性能、手感等的影响。结果表明:与未改性PU涂层相比,Si-PU涂层的拉伸强度、断裂伸长率均得到明显提升。当PDMS质量分数为7.6%时,改性涂层的拉伸强度较未改性PU涂层增长了51.9%;当PDMS质量分数为9.9%时,改性涂层的断裂伸长率较未改性PU涂层增长了99.3%;随着PDMS质量分数提高,质量损失速率最大的温度有一定提高,涂层的玻璃化温度逐渐降低,耐低温性能提高,同时疏水性提高,手感变得更加柔软,综合性能得到显著改善。

CTO/PCL-3057共混软段聚氨酯弹性体的相分离和力学性能

以蓖麻油(CTO)/聚己内酯三醇(PCL-3057)共混物为软段,三羟甲基丙烷为小分子交联剂,与多亚甲基多苯基多异氰酸酯(PAPI)反应,制备了软段中CTO质量分数分别为30%、50%、60%、70%和100%的聚氨酯弹性体(PUE),研究软段组成对PUE相分离结构和力学性能的影响。结果表明:CTO主要促进硬段之间氢键的形成,PCL-3057主要促进软硬段之间氢键的形成;两者各占50%时,PUE结晶性好,氢键度大,微相分离程度较完善,交联程度适当,所以力学强度高且韧性好。CTO柔顺性好,可以降低PUE软段的玻璃化转变温度(T_(gs)),而PCL-3057中极性基团过多会降低T_(gs);两者各占50%时,T_(gs)最大。PCL-3057都能显著提高PUE的动态力学性能。

兼具自修复和自消光性能的光固化聚氨酯涂层的制备与性能研究

采用联苯型双马来酰亚胺和糠醇合成了含Diels-Alder(DA)结构的联苯型二元醇,然后利用该二元醇与异佛尔酮二异氰酸酯、聚四氢呋喃及丙烯酸羟乙酯为原料制备了光固化自修复聚氨酯树脂,利用FT-IR和1H NMR对产物结构进行了表征,并测定了树脂光固化过程中的双键转化率,研究了DA二元醇用量对涂层性能的影响。结果表明:DA含量越大,涂层微相分离越明显,自消光效果越好,且涂层的自修复效果越显著,涂层修复后表面粗糙程度增大,光泽下降,涂层在修复3~4次后光泽趋于稳定。此外,随着DA含量的增加,涂层的玻璃化转变温度(T_(g))增大,且出现了2个T_(g)。当聚四氢呋喃与DA二元醇物质的量比为0.75∶1.25时,涂层兼具良好的自消光和自修复性能,损伤涂层经150℃修复后,划痕基本修复,光泽由初始光泽18.6下降至9.8,经3~4次修复后光泽稳定在4.5左右。

全生物基聚酯热熔胶的合成与性能研究

以生物基2,5-呋喃二甲酸(FDCA),油脂基氢化二聚酸(Pripol 1009)和生物基1,4-丁二醇(bio-BDO)为原料,采用熔融缩聚法制备了聚(2,5-呋喃二甲酸丁二醇酯-co-氢化二聚酸丁二醇酯)(PBDF-20)热塑性聚酯热熔胶,再将其应用于木材加工领域,并采用多种方法对PBDF-20及胶合板进行表征。研究结果表明:PBDF-20为半结晶性聚合物,具有纳米尺度的微相分离结构,分散相长周期为14.3 nm;其玻璃化温度和熔点分别为-12.8和148.6℃,拉伸强度及断裂伸长率分别为22.6 MPa和528%。以PBDF-20作胶黏剂,压制的杨木胶合板,胶合强度符合Ⅰ类胶合板要求,甲醛释放量<0.025 mg/m^(3),符合E_(NF)级标准。

用于信息存储与防伪的动态荧光防冻水凝胶

目的 为了提高水凝胶在恶劣环境下的适应能力,探究在信息存储与防伪中的应用前景,本次研究制备一种荧光聚合物水凝胶,提高水凝胶的机械稳定性、保湿性、多环境稳定特性,以及实现将代码信息隐藏在水凝胶内部的测试。方法 在70℃下将羧甲基纤维素钠(CMC)溶于水/二甲基亚砜(DMSO)体系,并在此基础上添加丙烯酸、丙烯酰胺、丙烯酸-2甲氧基乙酯等,用荧光溶液书写特定图案,最后将混合溶液进行紫外光固化,宏观上利用万能试验拉伸机、差式扫描量热仪对其进行力学与防冻性能表征;在微观上使用傅里叶红外光谱、扫描电子显微镜对其内部物质与形貌特征进行描述。结果 结果表明,水/DMSO体系可以提高低温下凝胶的力学性能;其次,制备得到的透明水凝胶在水浸泡下会出现溶胀现象,然后在DMSO溶液中恢复透明,利用这一现象可以实现荧光信息的隐藏与加密。结论 利用水凝胶在不良溶剂中的微相分离和有机溶剂中的溶胀现象,将荧光图案隐藏在其中,溶胀时紫外光下不显示信息,待恢复透明时信息可见,使其在信息加密领域具有广阔的应用前景。

HQEE改性PCL基形状记忆聚氨酯的制备

聚(ε-己内酯)(PCL)是一种半结晶性聚合物,由于其具有良好的可降解性和形状记忆性能,PCL的改性被广泛关注和研究。通过分子交联的方式将氢醌-双(β-羟乙基)醚(HQEE)引入一种具有树枝状拓扑结构的PCL基形状记忆聚氨酯。其中,六亚甲基二异氰酸酯作为固化剂、三羟甲基丙烷(TMP)作为交联剂。用傅里叶变换红外光谱分析、X射线衍射光谱分析、热重分析、差示扫描量热分析和形状记忆性能分析表征所制备的形状记忆聚氨酯(SMPU)。分析结果表明,异氰酸酯(—NCO)活性基团全部参与反应,成功制备得到SMPU试样。所制备的SMPU均具有结晶性,且其结晶性能随扩链剂(HQEE和三甲基戊二醇)含量的升高而降低,热降解性能良好,在30.9~40.2℃范围内出现结晶/熔融峰,形状回复率均为100%,形状固定率和形状回复时间均随扩链剂含量的增大而减小。综合分析得到,试样SMPU-H2和SMPU-H3的结晶性能适中,表现出良好的形状记忆性能。其中,SMPU-H2和SMPU-H3的硬段含量分别为38.51%和46.39%,形状记忆转变温度分别为35.5,34.7℃。

Synthesis and Microphase Separation Behavior of Random, Mixed Cylindrical Brush Copolymers Bearing Polystyrene and Poly(ε-caprolactone) Side Chains

A series of mixed, random cylindrical brush copolymers bearing polystyrene（PS） and poly（ε-caprolactone）（PCL） side chains were synthesized via the combination of ring-opening polymerization（ROP） and atom transfer radical polymerization（ATRP）. These novel cylindrical brush copolymers have been characterized by means of nuclear magnetic resonance（NMR） spectroscopy, gel permeation chromatography（GPC） and differential scanning calorimetry（DSC）. It was found that the mikto-armed cylindrical brush copolymers were microphase-separated in bulks and that the morphologies were dependent on the mass ratios of PS to PCL side chains. One of the cylindrical brush copolymers was employed to incorporate into epoxy thermoset to investigate effect of the mikto-armed cylindrical brush architecture on the reaction-induced microphase separation behavior. Depending on the concentration of the cylindrical brush in epoxy, the thermosets can display the morphologies with the spherical, worm-like and lamellar PS microdomains dispersing in continuous thermosetting matrices.

双连续相增韧离子凝胶的制备及水下黏附性能

以2-丙烯酸-2-甲氧基乙酯(MEA)和2-(全氟辛基)乙基甲基丙烯酸酯(FMA)为共聚单体,在混合离子体系中通过自由基聚合诱导相分离方法,制备了一种由刚性液晶相和柔性渗透相组成的双连续相P(MEA-co-FMA)离子凝胶黏结剂,并对其力学性能和水下黏附性能进行了详细研究。通过调节FMA单体及离子液体(IL)的组分比,来调控聚合物网络的微相分离结构和可逆的非共价键作用,以实现对离子凝胶力学性能和水下黏附性能的同步提升。结果表明:该疏水双连续相结构离子凝胶具有高达24.2 kJ/m^(2)的断裂韧性和1.76 MPa的断裂强度,对不同基材的水下界面黏附韧性最高可达2260 J/m^(2),界面黏附的疲劳阈值可达558 J/m^(2),表现出了长效耐久的水下黏附性。

Polymerization-induced microphase separation of polymer-polyoxometalate nanocomposites for anhydrous solid state electrolytes

Solid-state electrolytes(SSEs)with high ionic conductivity,mechanical stability,and high thermal stability,as well as the stringent requirement of application in high-temperature fuel cells and lithium-ion batteries is receiving increasing attention.Polymer nanocomposites(PNCs),combining the advantages of inorganic materials with those of polymeric materials,offer numerous opportunities for SSEs design.In this work,we report a facile and general one-pot approach based on polymerization-induced microphase separation(PIMS)to generate PNCs with bi-continuous microphases.This synthetic strategy transforms a homogeneous liquid precursor consisting of polyoxometalates(POMs,H_(3)PW_(12)O_(40),Li_(7)[V_(15)O_(36)(CO_(3))]),poly(ethylene glycol)(PEG)macro-chain-transfer agent,styrene and divinylbenzene monomers,into a robust and transparent monolith.The resulting POMs are uniformly dispersed in the PEG block(PEG/POM)to form a conducting pathway that successfully realizes the effective transfer of protons and lithium ions,while the highly cross-linked polystyrene domains(P(S-co-DVB))as mechanical support provide outstanding mechanical properties and thermal stability.As the POM loading ratio up to 35 wt%,the proton conductivity of nanocomposite reaches as high as 5.99×10^(-4) S/cm at 100℃ in anhydrous environment,which effectively promotes proton transfer under extreme environments.This study broadens the application of fuel cells and lithium-ion batteries in extreme environments.

EFFECT OF MOLECULAR WEIGHT AND FILM THICKNESS ON THE CRYSTALLIZATION AND MICROPHASE SEPARATION IN POLYSTYRENE-BLOCK-POLY(L-LACTIC ACID) THIN FILMS AT THE EARLY STAGE

We investigated the effects of molecular weight and film thickness on the crystallization and microphase separation in semicrystalline block copolymer polystyrene-block-poly（L-lactic acid） （PS-b-PLLA） thin films, at the early stage of film evolution （when Tg 〈 T 〈 TODT） by in situ hot stage atomic force microscopy. For PS-b-PLLA 1 copolymer which had lower molecular weight and higher PLLA fraction, diffusion-controlled break-out crystallization started easily. For PS-b-PLLA 2 with higher molecular weight, crystallization in nanometer scales occurs in local area. After melting of the two copolymer films, islands were observed at the film surface： PS-b-PLLA 1 film was in a disordered phase mixed state while PS-b-PLLA 2 film formed phase-separated lamellar structure paralleling to the substrate. Crystallization-melting and van der Waals forces drove the island formation in PS-b-PLLA 1 film. Film thickness affected the crystallization rate. Crystals grew very slowly in much thinner film of PS-b-PLLA 1 and remained almost unchanged at long time annealing. The incompatibility between PS and PLLA blocks drove the film fluctuation which subsequently evolved into spinodal-like morphology.