应用混合溶剂制备高性能聚噻吩有机薄膜晶体管

采用良溶剂与不良溶剂混合的方法,提高了聚3-己基噻吩(P3HT)薄膜晶体管的场效应迁移率.UV-Vis吸收光谱、掠角X-射线衍射和原子力显微镜研究表明,通过向P3HT的氯仿溶液中加入适量二氧六环可以增强溶液分子间π-π相互作用,在溶液中形成分子链有序排列的P3HT聚集体,从而提高了旋涂得到的聚合物薄膜结晶度,并控制分子沿着有利于电荷传输方向排列.薄膜的场效应迁移率在二氧六环的含量为10vol%时达到最高值1.7×10-2 cm2 V-1 s-1,与纯氯仿溶液制得的P3HT薄膜的迁移率相比提高了50多倍.     

溶剂沸点对聚(3-己基噻吩)薄膜内链结构与分子取向的影响

以聚(3-己基噻吩)(P3HT)为研究对象,借助荧光相关光谱、紫外-可见光谱和掠角红外光谱考察了溶剂性质对旋涂膜内P3HT的链结构与分子取向的影响。结果表明:溶液中P3HT的分子链构象受溶解度的影响,当P3HT溶解在溶解性好的良溶剂中时,链构象更伸展;固体薄膜内P3HT的物理结构却不受其在溶剂中溶解度大小的影响而具有沸点依赖性,溶解在高沸点溶剂中的P3HT旋涂后,薄膜内P3HT主链平面性与π-π相互作用均得到提高;此外,溶剂沸点的增加导致分子取向由"面朝上"方式转变为"边朝上"方式。     

利用相容剂调控聚噻吩/富勒烯共混薄膜形貌

选择含有噻吩环的富勒烯衍生物([6,6]-噻吩基-C61-丁酸甲酯(TCBM-Cn,n代表在噻吩环5位的烷基链碳原子数))作为聚3-己基噻吩(P3HT)和[6,6]-苯基-C61-丁酸甲酯(PCBM)共混体系的相容剂,讨论了结晶能力不同的TCBM-Cn分子对共混体系相容性和P3HT结晶行为的影响.当使用强结晶性的相容剂TCBM-C0时,虽然不能完全抑制PCBM的聚集,但由于分子中噻吩环结构的存在,少量的相容剂即可提高P3HT的结晶度.而对于弱结晶性的相容剂TCBM-C6,虽然可以完全抑制PCBM的聚集,但是只有当其含量超过PCBM时,最终才能达到促进P3HT结晶的目的.     

Cu2+对不同相形态中聚3-己基噻吩光学性质的影响

用紫外-可见吸收光谱和荧光光谱方法研究了Cu2+分别与稀溶液、分散液和薄膜三种体系中的聚3-己基噻吩(P3HT)的相互作用. 结果表明, P3HT的相形态对其相互作用有重要影响. 在四氢呋喃的稀溶液中, P3HT与Cu2+的溶剂化程度都很高, 它们之间几乎不存在化学作用; 在分散液中, P3HT形成聚集的颗粒, Cu2+的加入产生较弱的氧化掺杂, Cu2+部分进入到分散颗粒中; 在P3HT的薄膜中, Cu2+使链的共轭长度变短, 引起光吸收蓝移.     

聚N-异丙基丙烯酰胺接枝聚苯乙烯高分子刷的构象

当长链高分子高密度接枝到一个表面上时,由于分子链间的相互作用使得接枝的高分子链扩张而形成伸直链的构象,这种形态被称为高分子刷.     

一种基于聚噻吩-聚硒吩全共轭嵌段共聚物的合成及性质研究

全共轭刚性-刚性嵌段共聚物兼具嵌段共聚物的微相分离特性和共轭聚合物的光电性能，引起了人们越来越多的关注.基于此，我们利用格氏置换（GRIM）方法合成了全共轭刚性-刚性嵌段共聚物聚（3-己基硒吩）-b-聚（3-（6-羟基）-己基噻吩）（P3HS-b-P3HHT）.通过在噻吩段的烷基侧链末端引入羟基基团来丰富全共轭体系的溶液结构，并利用羟基的热交联特性提高聚噻吩均聚物的薄膜场效应晶体管的热稳定性.一方面，通过溶剂共混（氯仿/吡啶和甲醇/吡啶混合溶剂），调控P3HS-b-P3HHT分子在混合溶剂中的刚性-刚性相互作用，使P3HS-b-P3HHT在混合溶剂中自组装形成不同的纳米结构，如纳米带、纳米纤维和纳米微球等.另一方面，将P3HS-b-P3HHT和聚（3-己基噻吩）（P3HT）共混，利用羟基之间的热交联，使P3HS-b-P3HHT/P3HT共混薄膜在薄膜场效应晶体管中表现出较好的热稳定性.     

葡聚糖分子量和接枝度对阿霉素/白蛋白-葡聚糖纳米粒子体外抗肿瘤效果的影响

以Maillard反应制备的牛血清白蛋白-葡聚糖共价接枝物作为载体, 通过调节混合溶液的pH值和温度制备负载阿霉素的白蛋白-葡聚糖纳米粒子. 利用分子量为5×10³, 10×10³和62×10³的葡聚糖制备了多种共价接枝物, 研究了共价接枝物分子量对载药纳米粒子的粒径和稳定性及载药量的影响. 用短链葡聚糖(分子量5×10³和10×10³)制备的纳米粒子粒径为60 nm左右, 用长链葡聚糖(分子量62×10³)制备的纳米粒子粒径约为200 nm; 阿霉素的包埋效率为81%~98%, 包埋量为7.4%~16.9%. 细胞实验结果表明, 共价接枝物具有很好的生物相容性; 与自由阿霉素相比, 纳米粒子可以促进阿霉素进入人口腔上皮癌细胞; 受缓释性质的影响, 纳米粒子在低浓度时的细胞毒性要小于自由阿霉素. 与长链葡聚糖纳米粒子相比, 接枝度高的短链葡聚糖纳米粒子由于具有较小的粒径、 密集的葡聚糖分子刷表面、 一定的自由阿霉素浓度和较快的阿霉素释放速率, 因而更容易进入细胞并具有更好的体外抗肿瘤活性.     

聚苯胺共价接枝碳纳米管负载Pt催化剂的制备及对甲醇电催化性能的研究

以氨基化的碳纳米管为基体,通过界面聚合方法将聚苯胺共价接枝于碳纳米管表面,负载催化剂颗粒Pt. 通过透射电镜(TEM)、X射线衍射(XRD)及电化学方法对催化剂进行了表征. TEM结果表明通过界面聚合的方法可以使聚苯胺均匀地接枝于碳纳米管表面. 电化学测试结果表明,碳纳米管共价接枝聚苯胺作为载体可以提高催化剂的抗CO中毒性能,有利于对甲醇的催化氧化. 研究其对甲醇的催化活性,并与商业的JM(Pt/C)催化剂进行了对比. 结果表明,碳纳米管共价接枝聚苯胺,有效提高了催化剂的稳定性,延长催化剂的寿命.     

聚3-己基噻吩的制备及其荧光轨迹的研究

本文以3-己基噻吩为单体,无水FeCl3为氧化剂,在四氢呋喃(THF)中浓缩结晶制备了聚3-己基噻吩(P3HT),通过红外光谱、GPC、XRD和1H NMR表征其结构,测定了经THF浓缩前后P3HT的电流-电压曲线,并采用单分子光谱技术得到了其在介孔纳米TiO2基底上的荧光强度轨迹。结果表明,通过THF浓缩结晶能提高P3HT的相对分子量和其太阳能电池的能量转化效率,并且单分子P3HT/TiO2体系间界面电子的转移是不均一的,不但随着分子的不同而不同,而且还随着时间的不同而不同,其自相关函数呈非指数的衰减。     

核壳型Fe_3O_4@SiO_2磁性纳米粒子表面超支化聚乙烯共价接枝研究

报道了一种利用超支化聚乙烯(HBPE)对磁性纳米粒子表面进行共价修饰的方法.首先通过反相微乳液法合成表面包覆Si O2的磁性Fe3O4纳米粒子(Fe3O4@Si O2,简记为FS),并利用偶联剂3-丙烯酰基氧基丙基三氯硅烷对其进行改性,然后与α-二亚胺钯催化剂(Pd-diimine,1)反应,获得磁性粒子共价负载型催化剂(FS-Pd);进一步以所得催化剂在0.1 MPa和15℃下催化乙烯聚合,获得一系列表面HBPE共价接枝的磁性复合粒子(FS-HBPE).通过红外光谱(FTIR)、热重分析(TGA)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)、X射线衍射(XRD)、氢核磁共振波谱(1H-NMR)和凝胶渗透色谱(GPC)等技术对所得磁性复合粒子的结构和形貌进行了表征,并对其磁性能进行了评价.结果表明:通过表面引发/催化的链"行走"乙烯聚合,可成功实现HBPE在磁性纳米粒子表面共价接枝,通过聚合时间的改变,可对表面HBPE接枝率进行有效调控;所得FS-HBPE复合粒子呈超顺磁特征,借助HBPE的作用,可稳定分散于多个有机溶剂中,同时可实现快速磁控分离.基于上述优点,所得FS-HBPE磁性复合粒子可望用作贵金属催化剂载体,在相关有机反应中获得应用.     

Controlled synthesis of ZnS quantum dots and ZnS quantum flakes with graphene as a template

Novel ZnS quantum dots (QDs) and ZnS quantum flakes (QFs) were successfully prepared with graphene nanosheets (GNs) as a special template, and two unique heterostructures of ZnS/GNs were also obtained. Due to the structure-directing template effect of GNs, the as-synthesized ZnS with different morphologies, dots or flakes, were uniformly distributed on the surface of GNs by controlling nucleation and growth. The two different heterostructures of ZnS/GNs exhibited obvious photovoltaic response, and ZnS/GN QFs-on-sheet heterostructures show higher photovoltage than that of ZnS/GN QDs-on-sheet.     

Microstructure and anti‐ wear and corrosion performances of novel UHMWPE/graphene‐nanosheet composite coatings deposited by flame spraying

Ultra‐high molecular weight polyethylene (UHMWPE)/graphene‐nanosheet (GN, multiple layers of graphene sheets with the thickness of ~5–10 nm) coatings have been deposited by flame spraying. The structure of UHMWPE remained almost intact after the spray processing and addition of GNs resulted in a slightly decreased crystallinity and improved thermal stability of UHMWPE. In addition, the coating containing 1.0 wt.% GNs exhibited a reduction of ~20% in wear rate and 25% in friction coefficient (0.18 versus 0.24). Significantly enhanced anti‐corrosion performances of the UHMWPE–GN coatings were suggested by increased corrosion potential, corrosion current density, and impedance modulus value of the UHMWPE–GN coatings. The very well retained GNs are located mainly at the interfaces between UHMWPE splats and act as bridges connecting the splats, which mainly accounts for the enhanced properties of the composite coatings. The novel UHMWPE–graphene composite coatings show great potential for protecting engineering components for applications against corrosion. Copyright © 2013 John Wiley & Sons, Ltd.     

Novel approach for metallic surface-initiated atom transfer radical polymerization using electrografted initiators based on aryl diazonium salts

This paper reports on the preparation of poly(methyl methacrylate) (PMMA), poly(n-butyl acrylate) (PBA), and polystyrene (PS) brushes at the surface of conducting materials that were modified by the electrochemical reduction of a brominated aryl diazonium salt BF4-, +N2-C6H4-CH(CH3)-Br (D1). The grafted organic species -C6H4-CH(CH3)-Br was found to be very effective in initiating atom transfer radical polymerization (ATRP) of vinyl monomers. This novel approach combining diazonium salts and ATRP allowed PMMA, PBA, and PS brushes to be grown from the surface of iron electrodes. The polymer films were characterized in terms of their chemical structure by infrared reflection absorption spectroscopy and X-ray photoelectron spectroscopy. Atomic force microscopy studies indicated that the polymer brushes are densely packed. Contact angle measurements of water drops on PS and PMMA brushes were 88.1 +/- 2.0 and 70.3 +/- 2.1 degrees, respectively, which is consistent with the published wettability data for the corresponding polymer sheets.     

Structural hierarchy in melt-processed poly(3-hexyl thiophene)-montmorillonite clay nanocomposites: novel physical, mechanical, optical, and conductivity properties

Poly(3-hexyl thiophene) (P3HT) organically modified montmorillonite (om-MMT) polymer nanocomposites (PNCs) are prepared in the melt-cooled state. Hierarchical structures up to third order, namely, side chain mesomorph formation followed by the interchain lamellar structure of P3HT and finally its intercalation within the clay tactoids are observed. The structures are supported by transmission electron microscopy (TEM) and wide-angle X-ray scattering (WAXS) experiments. The TGA curves show two-stage degradation corresponding to those of the side chain and main chain of P3HT, and both temperatures decrease with an increase in clay concentration in the PNCs. The melting points of PNCs have increased by 2-3 degrees C higher than that of P3HT. The glass-transition temperature (Tg) and beta-transition temperature (Tbeta), measured by DMA, increase with an increase in clay concentration. The storage modulus (G) of PNCs has also increased more dramatically than that of P3HT. The UV-vis spectra of the PNCs show a blue shift in the pi-pi* absorption peak of the conjugated chain, but the photoluminescence spectra showed a red shift with an increase in the clay concentration. The quantum yield of the photoluminescence process also increases in the melt-cooled PNCs, and this is in sharp contrast to that of solvent cast PNCs where photoluminescence quenching was observed. Fibrillar network structure of the solvent cast PNCs promotes energy transfer of the charge carriers, but its absence in the melt-cooled films inhibits such energy transfer, increasing the quantum yield. The room-temperature dc conductivity of the PNCs decreased by an order compared to that of P3HT in both the doped and undoped states. The I-V characteristic curve shows semiconducting behavior, and it slowly transforms into insulator with increasing clay concentration.     

The nature of in-plane skeleton Raman modes of P3HT and their correlation to the degree of molecular order in P3HT:PCBM blend thin films

The nature of main in-plane skeleton Raman modes (C=C and C-C stretch) of poly(3-hexylthiophene) (P3HT) in pristine and its blend thin films with [6,6]-phenyl-C(61)-butyric acid methyl ester (PCBM) is studied by resonant and nonresonant Raman spectroscopy and Raman simulations. Under resonant conditions, the ordered phase of P3HT with respect to its disordered phase is identified by (a) a large shift in the C=C mode peak position to lower wavenumber (~21 cm(-1) shift), (b) a narrower fwhm of the C=C mode (~9 cm(-1) narrower), (c) a larger intensity of the C-C mode relative to the C=C mode (~56% larger), and (d) a very small Raman dispersion (~5 cm(-1)) of the C=C mode. The behavior of the C=C and C-C modes of the ordered and disordered phases of P3HT can be explained in terms of different molecular conformations. The C=C mode of P3HT in P3HT:PCBM blend films can be reproduced by simple superposition of the two peaks observed in different phases of P3HT (ordered and disordered). We quantify the molecular order of P3HT after blending with PCBM and the subsequent thermal annealing to be 42 ± 5% and 94 ± 5% in terms of the fraction of ordered P3HT phase, respectively. The increased molecular order of P3HT in blends upon annealing correlates well with enhanced device performance (J(SC), -4.79 to -8.72 mA/cm(2) and PCE, 1.07% to 3.39%). We demonstrate that Raman spectroscopy (particularly under resonant conditions) is a simple and powerful technique to study molecular order of conjugated polymers and their blend films.     

Transmission electron microscopy study of solvent-induced phase morphologies of environmentally responsive mixed homopolymer brushes on silica particles

We report in this work a transmission electron microscopy study of phase morphologies of environmentally responsive mixed poly( t-butyl acrylate) (P tBA)/polystyrene (PS) brushes and mixed poly(acrylic acid) (PAA)/PS brushes on 180 nm silica particles after treatments with nonselective good solvents and selective solvents, respectively. Mixed P tBA/PS brushes were grown from Y-initiator-functionalized silica particles by sequential atom transfer radical polymerization and nitroxide-mediated radical polymerization. Mixed PAA/PS brushes were prepared from mixed P tBA/PS brushes by removal of the t-butyl groups. For mixed P tBA/PS brushes with P tBA M n of 24.2 kDa and PS M n of 23.0 kDa and the corresponding mixed PAA/PS brushes, random worm-like, nearly bicontinuous nanostructures were formed from lateral microphase separation when the particles were cast from nonselective good solvents (chloroform for mixed P tBA/PS brushes and N, N-dimethylformamide for mixed PAA/PS brushes). The feature sizes were on the order of polymer chain root-mean-square end-to-end distances ( approximately 10 nm). In contrast, mixed P tBA/PS brushes with lower molecular weights (P tBA M n = 10.4 kDa and PS M n = 11.9 kDa) did not strongly phase separate after being cast from chloroform. After the solvents in the particle dispersions were gradually changed to selective solvents ( n-octane for mixed P tBA/PS brushes and H 2O for mixed PAA/PS brushes), isolated microdomains with an average size of 14-19 nm were formed as one grafted polymer collapsed and associated to form isolated microdomains, which were shielded by another grafted polymer yielding surface-tethered micellar structures. These results confirmed the theoretical predictions of the formation of "rippled" nanostructures and surface micellar structures of mixed homopolymer brushes induced by nonselective and selective solvents, respectively.     

Organic-inorganic nanocomposites via directly grafting conjugated polymers onto quantum dots

Nanocomposites of poly(3-hexylthiophene)-cadmium selenide (P3HT-CdSe) were synthesized by directly grafting vinyl-terminated P3HT onto [(4-bromophenyl)methyl]dioctylphosphine oxide (DOPO-Br)-functionalized CdSe quantum dot (QD) surfaces via a mild palladium-catalyzed Heck coupling, thereby dispensing with the need for ligand exchange chemistry. The resulting P3HT-CdSe nanocomposites possess a well-defined interface, thus significantly promoting the dispersion of CdSe within the P3HT matrix and facilitating the electronic interaction between these two components. The photophysical properties of nanocomposites were found to differ from the conventional composites in which P3HT and CdSe QDs were physically mixed. Solid-state emission spectra of nanocomposites suggested the charge transfer from P3HT to CdSe QDs, while the energy transfer from 3.5 nm CdSe QD to P3HT was implicated in the P3HT/CdSe composites. A faster decay in lifetime further confirmed the occurrence of charge transfer in P3HT-CdSe nanocomposites.     

Symmetric pH-dependent swelling and antibacterial properties of chitosan brushes

Charged polymer brushes grafted to surfaces are of great interest for antibacterial, biosensor, nanofluidic, and drug delivery applications. In this paper, chitosans with quaternary ammonium salts, CH-Q, were immobilized on silicon oxide and characterized by in situ quartz-crystal microbalance with dissipation, QCM-D, and in situ spectroscopic ellipsometry, SE. Both methods showed that the hydrated film exhibited a minimum thickness of ~40 nm near pH 5 that increased strongly (up to ~80 nm) at lower and higher pH. This symmetric swelling is surprising because CH-Q is a cationic polymer. The CH-Q grafted layer was stable for pH values from 3 to 8 and exhibited rapid, reversible swelling and contraction upon varying pH. The CH-Q layer also reduced S. aureus colonization by a factor of ~30× compared to bare silicon oxide and an amine terminated silane grafted to silicon oxide. This antibacterial characteristic of CH-Q is attributed to the quaternary ammonium salts and the flexible polymer brush.     

Surface-initiated synthesis of poly(3-methylthiophene) from indium tin oxide and its electrochemical properties

Poly(3-methylthiophene) (P3MT) was synthesized directly from indium tin oxide (ITO) electrodes modified with a phosphonic acid initiator, using Kumada catalyst transfer polymerization (KCTP). This work represents the first time that polymer thickness has been controlled in a surface initiated KCTP reaction, highlighting the utility of KCTP in achieving controlled polymerizations. Polymer film thicknesses were regulated by the variation of the solution monomer concentration and ranged from 30 to 265 nm. Electrochemical oxidative doping of these films was used to manipulate their near surface composition and effective work function. Doped states of the P3MT film are maintained even after the sample is removed from solution and potential control confirming the robustness of the films. Such materials with controllable thicknesses and electronic properties have the potential to be useful as interlayer materials for organic electronic applications.     

两亲性PS-b-PEG嵌段共聚物刷的合成及响应行为

利用原子转移自由基聚合(ATRP)和点击化学(Click)反应, 在硅基底上制备了聚苯乙烯-b-聚乙二醇(PS-b-PEG)两亲性嵌段共聚物刷. 首先, 利用ATRP方法在表面改性的硅片引发苯乙烯单体(St)的聚合, 得到PS-Br均聚刷, 然后通过叠氮化钠(NaN₃)将均聚刷末端功能化为PS-N₃, 再与炔基聚乙二醇甲醚(Alkynyl-PEG)发生Click反应, 得到PS-b-PEG嵌段共聚物刷. 通过X射线光电子能谱(XPS)和接触角测量仪表征了聚合物刷的表面化学组成和表面亲疏水性质, 证明在硅基底上接枝了嵌段共聚物刷. 用原子力显微镜(AFM)观察了PS-b-PEG嵌段共聚物刷在不同溶剂处理后的形态结构变化, 研究了其响应行为.