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首页> 外文期刊>Macromolecules >Structural Evolution of Nanograins during Cold Crystallization of Poly(9,9-di-n-octyl-2,7-fluorene) As Revealed via in Situ Small-Angle X-ray Scattering/Wide-Angle X-ray Scattering/Differential Scanning Calorimetry
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Structural Evolution of Nanograins during Cold Crystallization of Poly(9,9-di-n-octyl-2,7-fluorene) As Revealed via in Situ Small-Angle X-ray Scattering/Wide-Angle X-ray Scattering/Differential Scanning Calorimetry

机译：通过原位小角X射线散射/宽角X射线散射/差示扫描量热法揭示的聚（9,9-二-正辛基-2,7-芴）冷结晶过程中纳米颗粒的结构演变

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By means of ill situ small-angle X-ray scattering/wide-angle X-ray scattering/differential scanning calorimetry (SAXS/WAXS/DSC), structural evolution of poly(9.9-di-n-octly-2,7-fluorene) (PFO) in a cold crystallization process was quantitatively examined. After removal of background scattering from the fractal-like structure, SAXS profiles obtained during programmed heating of ail amorphous PFO specimen unveil a sequence of stages of structural evolution. These include (1) a frozen-in stage below the,lass transition temperature (T-g approximate to 62 degrees C) (2) the nucleation of prolate nano-rains with radius of gyration R-g approximate to 3.3 nm from 65 to 85 degrees C, (3) growth of the prolate ellipsoids LIP to R-g approximate to 5.0 nm between 95 and 105 degrees C. and (4) coalescence (and thickening) of the nanocrystals into oblates (of R-g approximate to 10 nm) upon further heating to 145 degrees C. There were no further changes in morphologoical features in the subsequent isothermal annealing at 145 degrees C for LIP to I h. as the size of the coalesced nanograins quickly reached a threshold value where the orientation and attachment of neighboring nanograins via thermally activated Brownian rotation became seriously hindered. Developments in the DSC-determined crystallinity (X-c,X-DSC) and the degree of heterogeneity (Q(inv) from SAXS) coincided with the nucleation and growth stages. respectively; in contrast, buildup of the WAXS-determined crystallinity (X-c,X-WAXS) proceeded mainly in the Subsequent coalescence stage where large nanocrystallites were developed.
机译：通过原位小角X射线散射/广角X射线散射/差示扫描量热法（SAXS / WAXS / DSC），研究了聚（9.9-二-n-辛基-2,7-芴）的结构演化（PFO）在冷结晶过程中被定量检查。从分形结构中消除背景散射后，在对所有无定形PFO样品进行程序加热期间获得的SAXS轮廓揭示了结构演化的一系列阶段。其中包括（1）在低于玻璃化转变温度（Tg约62摄氏度）的冻结阶段（2）在65至85摄氏度下回转半径Rg约3.3 nm的长形纳米雨核的形核， （3）在95到105摄氏度之间，长椭圆形LIP到Rg的生长大约为5.0 nm;（4）进一步加热到145摄氏度，纳米晶体聚结（和增厚）成扁圆形（Rg大约为10 nm） C.在随后的145°C等温退火（LIP至1 h）中，形态徽标特征没有进一步变化。随着聚结的纳米颗粒的尺寸迅速达到阈值，严重阻碍了相邻纳米颗粒通过热活化布朗旋转的取向和附着。 DSC确定的结晶度（X-c，X-DSC）和不均匀度（来自SAXS的Q（inv））的发展与成核和生长阶段相吻合。分别;相反，WAXS决定的结晶度（X-c，X-WAXS）的建立主要在随后的聚结阶段进行，该阶段出现了大的纳米晶体。

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