氟改性和硅改性丙烯酸聚氨酯涂层的制备及环境行为

目的研究氟改性和硅改性丙烯酸聚氨酯涂层在不同环境中的失效行为。方法通过溶液聚合法制备具有一定羟基含量的丙烯酸酯树脂,再将丙烯酸树脂与多异腈酸酯固化剂配合,获得丙烯酸聚氨酯涂层。通过在丙烯酸酯合成中引入含氟丙烯酸酯单体,制得氟改性丙烯酸聚氨酯涂层;通过在固化过程中引入氨基硅油,制得硅改性丙烯酸聚氨酯涂层。利用傅里叶变换红外光谱(FT-IR)分析涂层的化学组成。对涂层试样进行温度环境实验(室温和100,150℃)、湿热环境实验和氙灯老化实验,分析涂层疏水性、光泽度等表面特性的变化。结果氟、硅改性有效提高了涂层的疏水性。未改性、氟改性和硅改性三种涂层在100℃以下的环境中服役时,疏水性和光泽度比较稳定。硅改性涂层在150℃的高温环境中较未改性和氟改性涂层失效慢。湿热环境对三种涂层的接触角和光泽度等性能影响不大。氟改性涂层在氙灯老化环境中的失效程度较另外两种涂层轻。结论氟改性涂层耐光老化性能较好,硅改性涂层耐温性较好。     

双组份改性聚氨酯材料强疏水防腐表面性能研究

以全氟烷基醇(TEOH-10)对二苯基甲烷二异氰酸酯(MDI)进行修饰,通过扩链剂进行封端在聚氨酯侧链同时引入氟碳基团和疏水性基团实现双组份改性异氰酸酯,并通过TEOH-10/MDI的摩尔比控制含氟基团(-CF_2CF_3)的数量,制备改性聚氨酯(FPU-s)。以傅立叶红外光谱、核磁共振谱进行成分分析,扫描电镜观察涂层表面形貌、组织结构,分析微相分离结构的影响因素;随着含氟量增加,水接触角达到123.1°而具有强疏水性。本实验通过新型化学改性的方式制备了高水附着力、强疏水性及低表面性等优良性能的防腐蚀改性聚氨酯材料。     

低表面能改性聚丙烯酸酯的合成及防污性能研究

目的制备环境友好型的海洋防污涂料,即低表面能海洋防污涂料。方法以含氟单体甲基丙烯酸十二氟庚酯(FMA)和含硅单体γ-(甲基丙烯酰氧)丙基三甲氧基硅烷(KH570)为改性单体,以甲基丙烯酸缩水甘油酯(GMA)和丙烯酸丁酯(BA)为主要单体,通过自由基共聚合制得氟硅改性的聚丙烯酸酯树脂层,采用傅里叶红外光谱和差示扫描量热法,分别对改性聚丙烯酸酯树脂的化学结构和热性能进行了分析表征。通过对改性聚丙烯酸酯树脂涂层的扫描电子电镜(SEM)分析、接触角测试、表面能计算、附着力测试、耐酸碱测试,防污性能测试等,探讨了FMA和KH570含量对树脂涂层性能的影响。结果当FMA、KH570的含量分别为15%、10%时,树脂涂层的接触角达到112.0°,表面能低至18.425 m J/m~2,附着力达到1级,具有良好的防污性能。结论氟单体和硅单体单独参与共聚改性均具有降低聚丙烯酸酯树脂表面能的作用,而氟单体和硅单体共同改性聚丙烯酸酯对树脂涂层表面能的降低更显著,可作为一种很有潜力的海洋低表面能防污涂料。     

表面接枝含氟树脂改性HGB的制备及性能研究

目的对中空玻璃微珠(HGB)进行表面接枝含氟树脂改性,以其为填料制备含氟树脂涂料,并进行性能研究。方法将中空玻璃微珠分别经NaOH溶液、硅烷偶联剂KH550、HDI三聚体、含氟树脂处理,并通过FTIR、SEM、EDS等表征手段对接枝情况进行验证。以制备的表面接枝含氟树脂HGB(F-HGB)为填料,制备了含氟树脂隔热涂料,研究了HGB改性温度、时间对F-HGB接触角的影响,以及HGB粒径、添加量、改性、涂层厚度对涂料的疏水性能、隔热性能、拉伸强度的影响。结果成功制备出F-HGB,50℃下接枝含氟树脂反应8h,F-HGB与纯水的静态接触角为149.21°。与HGB/含氟树脂涂料相比,F-HGB/含氟树脂涂料的疏水性能、隔热性能、拉伸强度均有较大幅度的提高和改善。当F-IM16K添加量为20 phr时,F-HGB/含氟树脂涂层与水的接触角为100°,模拟曝晒实验涂层试板温差为7.4℃,拉伸强度为10.39 MPa。当F-K1添加量为20 phr时,F-HGB/含氟树脂涂层的导热系数为0.0701 W/(m·K),同时涂层隔热性能随HGB粒径、添加量的增大而增强,拉伸强度随之降低,但表面改性能有效减小涂料拉伸强度的降低幅度。结论 F-HGB具有疏水、隔热、与含氟树脂相容性好的特点,可作为功能填料制备疏水、隔热、力学性能优良的多功能涂料。     

核壳乳液聚合制备阳离子型含氟苯丙乳液的研究

目的合成出一种用于棉织物整理的阳离子型含氟苯丙乳液。方法选用全氟烷基乙基丙烯酸酯(PFEA)、丙烯酸丁酯(BA)、甲基丙烯酸甲酯(MMA)、苯乙烯(ST)及N-羟甲基丙烯酰胺(N-MA)等5种单体为原料,以2,2-偶氮二(2-甲基丙基咪)二盐酸盐为引发剂,采用半连续种子乳液聚合法合成了一种阳离子型含氟苯丙乳液。通过FT-IR、GPC、DSC及激光粒度仪对共聚乳液进行了表征。结果由于有机氟链段的自趋表能力,导致乳胶膜的疏水性随核壳比例的变化很小,但玻璃化温度Tg会因硬单体含量的增加而略有上升。同时,引发剂用量的增加会提高单体转化率,降低凝胶率,增大其质均分子量。FT-IR测试表明,聚合物中成功地引入了氟碳基团及其他官能团,激光粒度仪测得乳液的平均粒径为0.196?m,分布较窄。SEM显示经过整理后的棉织物表面较光滑平整,通过测定评级,防水达到95分,拒油达到6级,效果良好。结论核壳乳液聚合制备阳离子型含氟苯丙乳液反应过程平稳,将其用于纯棉织物的整理可使织物表面获得优异的防水拒油性能。     

生物涂层制备技术的研究现状及进展

羟基磷灰石(HA)由于具有良好的生物相容性和骨组织诱导性,被认为是替代人体硬组织的一种很好的生物医用材料,但其溶解度较高,降低植入体的长效性,而将氟渗入HA晶格中能提高HA结构稳定性并降低其溶解性,将硅掺入HA晶格中能有效地提高HA的生物活性,因此含氟羟基磷灰石(FHA)和含硅羟基磷灰石(Si-HA)成为了新兴的改性材料。介绍了羟基磷灰石(HA)、含氟羟基磷灰石(FHA)以及含硅羟基磷灰石(Si-HA)的性能特点以及涂层的制备技术,重点阐述了采用激光熔覆技术制备生物涂层的研究现状以及本课题组的研究进展,指出了目前研究中存在的不足,并展望了生物涂层今后的研究和发展趋势。     

基于含氟改性笼状倍半硅氧烷一步法制备透明超疏水涂层

目的 为了研究出一种在光滑镜面基材上大面积制备透明耐用的超疏水涂层,需要克服当前超疏水涂层存在的理化稳定性差、光学透明度不高以及制备繁琐、难以大面积实施等问题。方法 通过向聚氨酯丙烯酸酯疏水性光固化树脂体系中引入含氟低表面能改性的笼状倍半硅氧烷（POSS）,结合喷涂法和相分离法在聚碳酸酯（PC）表面制备了一种超疏水光固化涂层。探究了低表面能改性POSS的掺杂量和乙醇添加量对构筑超疏水涂层的影响。结果 当POSS-SH-DFMA7的掺杂量为树脂含量的40%、乙醇的添加量为溶剂THF的25%时,涂层表现出优异的超疏水特性,静态水接触角和滑动角分别可达到156.92°和3.24°;良好的光学透明性,光线透过率为85.63%;可靠的机械稳定性,承受6 h的水滴冲击后依然保持超疏水特性;稳定的耐候和耐化学性,经历户外环境和不同pH值化学试剂的侵蚀后仍可保持涂层原有的润湿性能。结论 在光固化树脂体系中引入一定量的含氟单体改性POSS结合乙醇的作用可以一步法制备出透明、理化性能稳定的超疏水涂层。     

透明耐磨疏水有机硅改性丙烯酸树脂的制备及性能

目的 研究不同丙烯酸类单体以及硅烷偶联剂配比对所制得的树脂涂层自清洁性能与机械性能的影响。方法 以甲基丙烯酸甲酯（MMA）、甲基丙烯酸羟乙酯（HEMA）、丙烯酸丁酯（BA）3种丙烯酸类单体与硅烷偶联剂（KH570）为原材料,采用自由基聚合法制备了具有透明耐磨性质的疏水有机硅改性丙烯酸树脂,加入羟基硅油使其交联固化,增强机械性能。重点研究了树脂涂层的接触角、附着力、硬度、透光率及耐摩擦等性能。结果 有机硅单体成功与丙烯酸类单体发生共聚,单因素优化后的树脂涂层的接触角为106.7°,与基体结合力为0级,硬度为H,在可见光波段内,涂覆在玻璃基底上的树脂最高透光率为92.08%,同时涂层具有良好的致密性。结论 将硅烷偶联剂（KH570）与丙烯酸类单体进行共聚,硅烷偶联剂的长链明显提升了共聚物的疏水性与稳定性,经交联固化后涂层表现出良好的机械性能与稳定性,并且由于所加单体的折射率都<1.5,因而涂层表现出一定的增透效果。     

UV固化有机硅改性聚氨酯易清洁涂层的制备及性能研究

目的 研究聚二甲基硅氧烷(PDMS)相对分子质量、官能度及添加量对紫外光(UV)固化聚氨酯丙烯酸酯易清洁涂层防污性能的影响。方法 以聚乙二醇(PEG)、异佛尔酮二异氰酸酯(IPDI)、羟基封端的PDMS和季戊四醇三丙烯酸酯(PETA)为原料,采用一锅法制备了有机硅改性聚氨酯丙烯酸酯易清洁树脂,并UV固化得到易清洁涂层。结果 添加5 000相对分子质量PDMS(PDMS–5000)的涂层比添加1 000相对分子质量PDMS(PDMS–1000)的涂层具有更高的接触角、更低的滑动角、更好的油性记号笔笔迹收缩效果和耐磨性能,但涂层透过率明显降低;添加双羟基封端的PDMS(PDMS–B)的涂层比添加单羟基封端的PDMS(PDMS–A)的涂层具有更好的油性记号笔笔迹收缩效果和耐磨性能。随着涂层中PDMS的添加量从0.5%提高到2.0%,防污性能逐渐提高。同时根据XPS分析可知,当涂层中PDMS的添加量提高到2%时,涂层表面的Si含量接近饱和,防污性能达到最佳。易清洁涂层即使经过1 000次的磨损循环测试后,依然具有油性记号笔笔迹收缩效果。结论 PDMS–B改性的聚氨酯丙烯酸酯涂层比PDMS–A改性的聚氨酯丙烯酸酯涂层具有更优异的记号笔笔迹收缩性能和耐磨性能,而且PDMS–5000改性的聚氨酯丙烯酸酯涂层比PDMS–1000改性的聚氨酯丙烯酸酯涂层具有更好的易清洁性能。当PDMS的添加量从0.5%提高到2.0%时,涂层的疏水疏油性能逐渐提高。     

低表面能涂层老化性能研究

合成了全氟丙烯酸酯类聚合物,添加到涂料中制成低表面能涂层;将低表面能涂层暴露在室外或紫外灯下,发现全氟丙烯酸酯类低表面能材料疏水性能会迅速失效,利用红外光谱仪和X射线光电子能谱研究低表面能涂层的失效规律,涂层表面的羟基或双键等活性基团氧化可能是失效的主要原因。     

Copolymers based on fluorene dyads mixed to 3,4-ethylenedioxythiophene units: Optical properties of random versus regular structures

We report on the synthesis of two copolymers containing both ethylenedioxyhiophene (EDOT) derivatives and dihexylfluorene (DHF) units. In one hand, a set of copolymers was obtained by dehalogenating Yamamoto coupling from a feed solution of both monomers. This route leads to materials with a random composition of each monomer. The substitution by a tetradecyloxy chains on the dioxyethylene ring ensures a good solubility of the copolymer when increasing the proportion of the EDOT units in the structure. On the other hand, the second polymer was synthesized by Suzuki cross-coupling, the resulting structure being a fully alternated of one EDOT and two DHF. All polymers were characterised by steric exclusion chromatography, indicating in all cases that small polymeric chains are obtained. FT-IR and ¹H NMR spectroscopy were investigated in order to solve the structure and to determine the EDOT/fluorene ratio of the random materials. The electronic and optical properties were investigated by UV–vis spectroscopy and Photoluminescence experiments. The role of EDOT units on the electronic structure of the copolymers has been established; mainly the electron-rich EDOT ring increases the HOMO energetic level. This observation is confirmed by cyclic voltamperometry experiments. This trend is also observed within a regular polymeric sequence. While the optical properties are finely controlled in this case, the photoluminescent properties are drastically hindered by the π-stacking that results from the highly ordered material during the cast process. These results confirm our choice to built electroluminescent devices with the random copolymers as active layers. Green light emission is obtained with moderate emission.     

WC-Co reinforced NiCoCrAlYTa composite coating: Effect of the proportion on microstructure and tribological properties

The properties of the working surfaces are linked to the safety and lifespan of the modern machines so that variety of coatings are used to protect the parts from breakdown. The NiCoCrAlYTa coating, which has an excellent oxidation resistance, usually undergoes more serious friction and wear due to its lower micro-hardness in contrast to the ceramic coatings. Therefore, the composite coatings reinforced by WC-Co are prepared by HVOF sprayed technology and are also characterized by scanning electron microscope, Raman spectrometer and X-ray diffraction. At the same time, the friction and wear behaviors as well as the mechanisms of different friction pairs are also discussed, in detail. The composite coatings, which mainly consist of γ-(Ni, Co), β-NiAl, γ′-Ni₃Al, WC and W₂C, are dense and uniform. With the increase of WC-17Co, the microhardness of NiCoCrAlYTa/WC-Co composite coating has enhanced from 641.4 HV_300g to 859.7 HV_300g. The wear rates of the composite coatings (10⁻⁵–10⁻⁶ mm³·N⁻¹ m⁻¹) are far lower than those of the as-sprayed NiCoCrAlYTa coating (10⁻⁴ mm³·N⁻¹ m⁻¹). Overall, the mechanical properties and tribological behaviors of the coatings are greatly improved with the addition of WC-Co.     

Experimental and theoretical studies on protective properties of poly(pyrrole-co-N-methyl pyrrole) coatings on copper in chloride media

The corrosion inhibition behaviour of poly(pyrrole-co-N-methyl pyrrole) films synthesized from oxalic acid solutions containing different ratios of monomers (Py:NMPy 8:2, 6:4, 5:5, 4:6, 2:8) has been examined. For this aim, E_ocp–time curves, anodic polarization and EIS techniques were used. Synthesized copolymer films exhibited significant protection efficiency against corrosion of copper in 3.5% (w/v) NaCl and 8:2 ratios of monomers gave the most protective copolymer coating. Quantum chemical approach was utilized in order to correlate corrosion inhibition performance of all copolymers. Experimental protection efficiencies are supported by density functional theory (DFT) calculations.     

Growth of Mn, Co and Ni-doped near-stoichiometric LiNbO3 by Bridgman method using K2O flux

The near-stoichiometric LiNbO₃ (SLN) single crystals doped Mn²⁺, Co²⁺ and Ni²⁺ in 0.5 mol% concentration in the raw compositions were grown by the Bridgman method under the conditions of taking K₂O as flux, a high temperature gradient (90–100 °C/cm) for solid–liquid interface. The XRD, absorption spectra, excitation spectra and emission spectra have been carried out. From the absorption edges of Mn²⁺, Co²⁺ and Ni²⁺-doped SLN crystals, the molar ratio of [Li⁺]/[Nb⁵⁺] are estimated to be about 0.977. The absorption spectra of Mn²⁺:SLN have shown a broad absorption band centered at 571 nm (⁶A_1g(⁶S) → ⁴T_1g(⁴G)), three absorption peaks at 520, 549 and 612 nm (overlapping of the ⁴T₁(F)–⁴A₂(F), ⁴T₁(F)–⁴T₁(P)), and a wide absorption band at 1400 nm (⁴T₁(F) → ⁴T₂(F)) of Co²⁺:SLN, Ni²⁺:SLN, and five absorption peaks at 381 nm (³A_2g(F) → ³T_1g(P)), 733 nm (³A_2g(F) → ³T_1g(F)), 1280 nm (³A_2g(F) → ³T_2g(F)), 430 nm (³A_2g(F) → ¹T_2g(D)), and 840 nm (³A_2g(F) → ¹E(D)) of Ni²⁺:SLN were observed. A red emission at 612 nm (⁴T_1g(⁴G) → ⁶A_1g(⁶S)) for Mn²⁺:SLN, a red emission at 775 nm (⁴T₁(P) → ⁴T₁(F)) for Co²⁺:SLN, and a green emission at 577 nm (¹T_2g(D) → ³A_2g(F)) and a red emission at 820 nm (¹T_2g(D) → ³T_2g(F)) for Ni²⁺:SLN were observed under excited by 416, 520 and 550 nm lights, respectively. The concentration distribution of Mn²⁺, Co²⁺and Ni²⁺ ion in SLN crystals was investigated primarily from the absorption and emission spectra for various parts. The effective distribution coefficient for Mn²⁺ was less than 1. While, for Co²⁺ and Ni²⁺ were more than 1.     

Synthesis and characterization of aniline copolymers containing carboxylic groups and their application as sensitizer and hole conductor in solar cells

Copolymers of m-aminobenzoic acid and o-anisidine doped with p-toluenesulphonic acid in different proportions were successfully synthesized by oxidative polymerization. The copolymers were characterized by FT-IR, UV–vis, ¹H NMR and EPR spectroscopies, cyclic voltammetry, conductivity and SEM. The copolymer with equivalent amounts of the monomers o-anisidine and m-aminobenzoic acid presented the highest conductivity, The EPR analyses and SEM images show that this copolymer provides more homogeneous films with particle size distribution of approximately 1–2 μm. The copolymer with a high fraction of o-anisidine gives rises to films with larger particle sizes and a more defined electrochemical process. The m-aminobenzoic acid monomer was intentionally chosen in order to promote a better electronic coupling between the conducting copolymer and the TiO₂ surface. The copolymers were tested as both sensitizers and hole conducting materials in dye-sensitized solar cells. The device assembled using the copolymer with the highest proportion of m-aminobenzoic acid units as sensitizer produced the highest photocurrent (I_sc = 0.254 mA cm^?2) and photovoltage (V_oc = 0.252 V) at 100 mW cm^?2. The energy diagram shows that although the electronic injection from the conducting polymer excited state is an allowed process the regeneration of the positive charges created after the electron transfer process is forbidden, thus explaining the low efficiency of solar energy conversion. When this copolymer was applied as a hole conducting material, an improvement in the V_oc to 0.4 V, was observed, indicating that this material is more suitable for charge transport when applied in this type of solar cells.     

Synthesis and photovoltaic properties of the copolymers of 2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylene vinylene and 2,5-thienylene-vinylene

The random copolymers of 2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylene vinylene (MEH-PV) and 2,5-thienylene-vinylene (ThV) were synthesized by Gilch method [H.G. Gilch, W.L. Wheelwright, J. Polym. Sci. Part A, Polym. Chem. 4 (1996) 1337; H. Becker, H. Spreitzer, K. Ibrom, W. Kreuder, Macromolecules 32 (1999) 4925; J.A. Mikroyannidis, Chem. Mater. 15 (2003) 1865], the alternate copolymer of MEH-PV and ThV was synthesized by Hornor–Emmons reaction, and poly(3-hexyl-thienylene-vineylene) was synthesized by Stille coupling reaction. The absorption characteristics of the copolymers were modulated by changing the ratio of ThV to MEH-PV units in the copolymers. With the increase of the ThV ratio, the absorption spectra of the copolymers were broadened and red-shifted in comparison with that of MEH-PPV. Hole mobility of the random copolymer with 18% ThV is an order higher than that of MEH-PPV. The polymer photovoltaic cells based on the blend of the copolymer and C₆₀ were fabricated and characterized by I–V and input photon to converted current efficiency (IPCE) measurements. Energy conversion efficiency under a white light (70 mW/cm²) of the photovoltaic cell based on the copolymer containing 18% ThV increased by 47% in comparison with that of the device based on MEH-PPV. The performance improvement of the polymer photovoltaic cell based on the random copolymers should benefit from the broader absorption and higher hole mobility of the copolymers.     

Features of the thermal behavior of PMMA/C<Subscript>60</Subscript> film composites

Polymethylmethacrylate-based film composites containing small additives of fullerenes (up to 3 wt %) are obtained. The thermal behavior of the obtained materials is studied by DSC in the temperature range from 25 to 130°C. It is found that the character of the DSC curve depends on the composite composition. For films containing up to 0.1 wt % C₆₀, one glass transition temperature (T _g ^soft) is observed, while in the case of films with a higher concentration of the filler, two glass transition temperatures (T _g ^soft and T _g ^solid) are observed. It is found that the dependence of T _g ^soft value on the content of fullerenes is nonmonotonic with a minimum at 0.5 wt % of C60.     

Optical and electrical characteristics of poly(3-alkylthiophene) and polydiphenylamine copolymers: Applications in light-emitting devices

In this work, poly (3-methylthiophene) (P3MT) or poly (3-octylthiophene) (P3OT) films were synthesized electrochemically with polydiphenylamine (PDFA), in layers and blended copolymers, in non-aqueous media through the oxidation of the monomers, using a standard three-electrode cell in acetonitrile with 0.100 mol L⁻¹ LiClO₄. The polymeric thin films were deposited on platinum plates for optimal quality control of the process. The electrochemical behaviors of as-prepared and partial dedoped films obtained by these methods was verified by cyclic voltammetry (CV) and have been characterized by UV–vis reflectance, resonance Raman, electron paramagnetic resonance (EPR) and photoluminescence (PL) spectroscopy. Based on data obtained by UV–vis reflectance spectroscopy, it was possible to characterize the chemical species in the polymer matrix using the resonant Raman method. Both Raman and PL spectra results led to the characterization of three structures (aromatic, semi-quinone and quinone forms of thiophene rings) which formed the homopolymers and copolymers chain. The EPR measurements were taken to quantify the semi-quinone species stabilization at 298 and 77 K temperatures. The ionization potential (I_P), electron affinity (E.A.) and gap energy (E_g) parameters were determined based on the technical analyses carried out.     

A study of electroless copper-phosphorus coatings with the addition of silicon carbide (SiC) and graphite (Cg) particles

Copper composite coating with graphite (C_g) and/or silicon carbide (SiC) particles were deposited by electroless plating. The surface morphology of the coatings that were analysed using scanning electron microscopy (SEM) showed that Cu particles were uniformly distributed. The obtained coating thickness was approximately ± 5 μm. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) techniques were used to characterise the structure and to study the phase transition of the coatings, respectively. Phases such as Cu, Cu₂O, Cu₃P, Cu₃Si, SiC and C_g were observed from X-ray diffraction patterns and the presence of Cu₂O, Cu₃P and Cu₃Si was confirmed by differential scanning calorimetry (DSC) studies. The results demonstrated that SiC and C_g particles have little influence on the phase transition of the coating. The hardness and wear resistance of Cu-P composite coatings were improved with the incorporation of SiC particles. The friction coefficient of Cu-P composite coatings decreased with the incorporation of C_g particles. Atomic force microscopy (AFM) results of coatings showed that the roughness of the coatings increased with the incorporation of SiC to the Cu-P coatings and decreased with the incorporation of C_g. Cu-P-C_g-SiC composite coatings showed a moderate roughness, hardness between Cu-P-SiC and Cu-P-C_g coatings, had low friction and good anti-wear properties. The anti corrosion resistance of the electroless Cu-P composite coatings on carbon steel were studied in 3.5% NaCl and 1 M HCl solutions by the potentiodynamic polarisation technique. The study revealed that the corrosion resistance increased with the incorporation of SiC particles in the Cu-P and Cu-P-C_g matrix but reduced with the incorporation of graphite.     

Structure-phase morphology – Property relationship of a series of light-emitting alternating copolymers with distyrylbenzenes segments and oligo(ethylene oxide) spacers

A series of light-emitting alternating copolymers: DSB–TEO, DSB–SEO, DSB–PEO₁₅₀₀ and dimethoxy(DM)DSB–SEO, consisting of 1,4-distyrylbenzene (DSB) and different length of ionic conducting oligomer ethylene oxide (OEO) spacers, were synthesized. The thermal stabilities, electrochemical behavior and photoluminescent properties of these polymers were studied systematically. It was found that with increasing OEO chain length, the solubility, film-forming property and relative fluorescence quantum yield were improved accordingly. The introduction of two methoxy groups as side chains into the DSB segment to form DMDSB not only enhanced the film-forming property, but also improved the quantum efficiency of the polymer. Phase contrast microscopy, polarized optical microscopy and atomic force microscopy (AFM) were employed to investigate the phase morphology of the thin films prepared from the pure polymer or polymer/LiCF₃SO₃ blends. Results revealed that compared with pure polymer thin films, there was significant change in the phase morphology of the thin films prepared from polymer/LiCF₃SO₃ blends. The reason could be attributed to the contrary roles of dissolved and undissolved lithium salt played in the polymer matrix, which was discussed in detail in the paper. Phase morphology study of DMDSB–SEO revealed that, compared with DSB–SEO, there was much less crystallization of OEO segments and the solubility of lithium salt had increased greatly. Furthermore, AFM was used to investigate the dependence of surface morphology on the spin-coat processing conditions, such as the solvents, substrates and rotation rate. A light-emitting electrochemical cell device of the copolymer was fabricated, and the brightness and maximum external quantum efficiency of the device were investigated.