Fabrication of nanostructured poly(3-thiophene methyl acetate) within poly(vinylidene fluoride) matrix: new physical and conducting properties.
Fabrication of nanostructured poly(3-thiophene methyl acetate) within poly(vinylidene fluoride) matrix: new physical and conducting properties.
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DOI：
10.1021/jp909794b
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发表时间：
2010-01
期刊：
影响因子：
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通讯作者：
S. Manna;A. Mandal;A. Nandi
中科院分区：
文献类型：
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作者：
S. Manna;A. Mandal;A. Nandi
采用反应共混技术，在熔融冷却条件下制备了聚偏氟乙烯(PVDF)基质中的纳米结构聚3-噻吩乙酸甲酯(PTMA)。当PTMA浓度为5%(w/w)时，纳米粒子几乎呈球形，其最小尺寸为5%(w/w)，当PTMA浓度为-gt；或=25%(w/w)时，纳米颗粒形成团聚。用不同的相分离机理解释了纳米颗粒尺寸的上述变化。PTMA5共混物中较小尺寸的纳米相属于调幅分解，而较大尺寸的纳米相是由二节点分解产生的。热重分析表明，PVDF在纳米共混物中的热稳定性有所提高。DSC研究表明，纳米共混物的熔融和结晶温度升高，前者是由于PTMA纳米结构的引力所致，后者是由于纳米相PTMA的成核作用。长程距、片层间距和非晶覆盖层间距均有不同程度的减小。紫外可见光谱的pi-pi*跃迁带随PTMA浓度的增加而红移，而纳米棒的光致发光光谱则蓝移。前者归因于PTMA的链内聚集，后者归因于基态“静态准分子”的形成。除了PTMA5外，PTMA1和PTMA3的发光强度增加了约8倍，其中纳米结构域之间的互连使非辐射衰减类似于块体PTMA。电导率的温度变化表明，随着温度的升高，PTMA链发生构象转变，有利于更好的电荷传输。I-V特性曲线非常有趣；纳米棒表现出负滞后，但PTMA5表现出记忆效应，这归因于由旋节分解产生的相互连接的纳米相产生的电双稳。
Nanostructured poly(3-thiophene methyl acetate) (PTMA) within the poly(vinylidene fluoride) (PVDF) matrix is achieved by reactive blending technique under melt-cooled condition. The nanoparticles are almost spherical showing a minimum size with 5% (w/w) PTMA concentration (PTMA5), and they become agglomerated at > or = 25% (w/w) PTMA concentration. Different phase separation mechanisms are used to explain the above variation of nanoparticle size. The lower size nanophase in the PTMA5 blend is attributed to spinodal decomposition, while the larger size nanophases are produced from binodal decomposition. The TGA study indicates increasing thermal stability of PVDF in the nanoblends. DSC study shows increasing melting and crystallization temperature of the nanoblends; the former is due to the attractive forces of PTMA nanostructure, and the latter is for the nucleating effect of nanophase PTMA. The long distance, lamellar distance, and amorphous overlayer distance decrease to different extents. The pi-pi* transition band of UV-vis spectra shows a red shift with increasing PTMA concentration, but the photoluminescence spectra of the nanoblends show a blue shift. The former is attributed to intrachain aggregation of PTMA, while the latter is caused from "static excimer" formation at the ground state. PTMA1 and PTMA3 show approximately 8 times increase in PL intensity except PTMA5 where interconnectivity between the nanodomains makes the nonradiative decay similar to bulk PTMA. The temperature variation of conductivity indicates a conformational transition of PTMA chain with increasing temperature facilitating better charge transport. The I-V characteristic curves are really interesting; the nanoblends show a negative hysterisis, but PTMA5 shows a memory effect attributed to the electrical bistability originated from the interconnected nanophases arising from spinodal decomposition.