Formation and Thermally-Induced Disruption of Nanowhiskers in Poly(3-hexylthiophene)/Xylene Gel Studied by Small-Angle X-ray Scattering

Chen, Chun-Yu; Chan, Shu-Hua; Li, Jianyi; Wu, Keng‐Liang; Chen, Hsin‐Lung; Chen, Jean-Hong; Huang, Wen-Yao; Chen, Show‐An

doi:10.1021/ma1008034

Cited by 55 publications

(75 citation statements)

References 33 publications

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“…The formation of nanowhiskers in the P3HT/ xylene gel under study was verified by SAXS. As shown in Figure S5 of the Supporting Information, the observed SAXS profile of the aged gel can be fitted well by the form factor of a long rectangular parallelepiped with the width and thickness of 20.7 and 5.4 nm, respectively, 26 indicating that the scattering intensity was dominated by the nanowhiskers due to their abundance in the gel. Figure 6 shows the AFM topographic images of the films as cast from the solution and the gel for resolving the characteristic nanostructures in the films.…”

Section: ■ Results and Discussionmentioning

confidence: 65%

“…It has been reported previously that P3HT chains in the liquid solution formed fractal structure due to a certain degree of segmental association. 26,37,38 Upon prolonged aging, P3HT chains selforganized to form nanowhiskers, 42 where the extensive networking of the whiskers may give rise to the gel property of the system. The formation of nanowhiskers in the P3HT/ xylene gel under study was verified by SAXS.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Gelation of a Solution of Poly(3-hexylthiophene) Greatly Retards Its Crystallization Rate in the Subsequently Cast Film

Kao

Chen

et al. 2014

J. Phys. Chem. B

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We compared the crystallization rate of poly(3-hexylthiophene) (P3HT) in the film cast from the gel (called "gel-cast film") with that in the film cast from the liquid solution (called "solution-cast film") to understand the effect of solution structure on the structural development in the subsequently cast film of conjugated polymer. P3HT was found to form a homogeneous liquid solution with xylene at elevated temperature. When the freshly prepared semidilute solution was allowed to age at room temperature, the solution transformed into a gel in which a significant amount of nanowhiskers formed. The nanowhiskers in the gel were effectively transferred to the corresponding cast film, while the film cast from the freshly prepared solution only contained a small amount of such a morphological entity. The in situ small-angle X-ray scattering (SAXS) measurement and thermal analysis revealed that both the cold and melt crystallization of P3HT in the gel-cast film were much slower than those in the solution-cast counterpart. The retardation of crystallization rate in the gel-cast film was attributed to the abundance of the nanowhiskers. In this case, the crystallization of P3HT occurred predominantly within the individual nanowhiskers and the mesh regions in the networks of the whiskers, where their limited sizes in at least one dimension imposed a strong spatial constraint to the crystal growth and chain motion for crystallization.

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Section: ■ Results and Discussionmentioning

confidence: 65%

Section: ■ Results and Discussionmentioning

confidence: 99%

Gelation of a Solution of Poly(3-hexylthiophene) Greatly Retards Its Crystallization Rate in the Subsequently Cast Film

Kao

Chen

et al. 2014

J. Phys. Chem. B

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“…84 The parallelepiped model was chosen to reflect the orthorhombic crystal structure of P3HT, although cylindrical models have also been used to fit SAXS data of similar systems. 88 The fractal dimension, D f of the network 20,89 was obtained as the exponent of the power law scattering (blue line, Fig. 5).…”

Section: P3ht-containing Gels and Filmsmentioning

confidence: 99%

Practical applications of small-angle neutron scattering

Hollamby

2013

Phys. Chem. Chem. Phys.

125

116

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Recent improvements in beam-line accessibility and technology have led to small-angle neutron scattering (SANS) becoming more frequently applied to materials problems. SANS has been used to study the assembly, dispersion, alignment and mixing of nanoscale condensed matter, as well as to characterise the internal structure of organic thin films, porous structures and inclusions within steel.Using time-resolved SANS, growth mechanisms in materials systems and soft matter phase transitions can also be explored. This review is intended for newcomers to SANS as well as experts. Therefore, the basic knowledge required for its use is first summarised. After this introduction, various examples are given of the types of soft and hard matter that have been studied by SANS. The information that can be extracted from the data is highlighted, alongside the methods used to obtain it. In addition to presenting the findings, explanations are provided on how the SANS measurements were optimised, such as the use of contrast variation to highlight specific parts of a structure. Emphasis is placed on the use of complementary techniques to improve data quality (e.g. using other scattering methods) and the accuracy of data analysis (e.g. using microscopy to separately determine shape and size). This is done with a view to providing guidance on how best to design and analyse future SANS measurements on materials not listed below.

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“…The absence of characteristic reflections in the SAXS curves suggests that as-synthesized P3HT adopts the form of nanowhiskers, as reported earlier. [19] Recrystallization of P100 from the melt led to a lamellar structure with a long spacing of about 14 nm (see Figure S2). In contrast, SAXS patterns recorded for P200 before and after melt-crystallization are identical.…”

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confidence: 99%

A Strategy for Revealing the Packing in Semicrystalline π‐Conjugated Polymers: Crystal Structure of Bulk Poly‐3‐hexyl‐thiophene (P3HT)

et al. 2012

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Polymers with extended p-conjugation and low band gaps are of broad scientific interest because of their promising applications as semiconductors in organic electronic devices. Examples include organic photovoltaic (OPV) cells, organic field-effect transistors (OFETs), and organic light-emitting diodes (OLEDs) with optimized properties toward light harvesting, charge-carrier mobility, and light emission, respectively. [1] Such polymers with lamellar p-stacks exhibit phase separation with regions of high and low order, that is, with crystalline and amorphous domains. This behavior is typically referred to as semicrystallinity, which is well known from polyolefins. [2] The specific organization of the macromolecules depends on the processing conditions. [3] Heterogeneous packing is also observed in photoconducting, columnar structures based on discotic aromatic compounds. [4] However, because the charge transport in such systems critically depends on the local packing, [5] structural details at the atomic level are of the utmost importance for material development. X-ray diffraction (XRD), which is well established in this area, requires high order, like that of single crystals. Even from a fiber diagram, only information about the relative assembly on a crystallographic lattice or chain-tochain and p-p stacking distances can be derived. [6] Thus, a "multi-technique" approach is required to elucidate such structures. [7] Recently, the combination of nuclear magnetic resonance (NMR) spectroscopy and quantum-chemical calculations of NMR properties, such as isotropic chemical shifts, J-couplings, and quadrupolar coupling parameters, has been established as a powerful approach to elucidate the structure of microcrystalline materials with atomic resolution, [8] often referred to as NMR crystallography. [9] In our study, we extend this approach to include XRD to handle semicrystalline polymers, for which single crystals are not available, placing emphasis on p-conjugated polymers. Our strategy is based on the use of XRD to assess long-range order from powder or fiber diagrams, and to employ high-resolution 1 H and 13 C solid-state NMR spectroscopy to acquire molecular constraints. The latter technique exploits the sensitivity of NMR spectroscopy toward local packing and conformations through 1 H and 13 C NMR chemical shifts and 1 H-1 H dipoledipole couplings (DDCs). [10] Quantitative and specific packing information is obtained from quantum-chemical calculations of chemical shifts with the aid of nucleus-independent chemical shift (NICS) maps. [11] The NICS approach is particularly suited to quantify p-p stacking with 1 H NMR chemical shifts as a fingerprint of lamellar structures in polymers with extended p-conjugation. Specifically, we evaluated how the local magnetic fields are shielded (or deshielded) by neighboring chains within a stack. This evaluation enabled us to analyze the experimentally observed differences between solution-and solid-state 1 H NMR chemical shifts. Thus, we were able to identify packing mode...

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Formation and Thermally-Induced Disruption of Nanowhiskers in Poly(3-hexylthiophene)/Xylene Gel Studied by Small-Angle X-ray Scattering

Cited by 55 publications

References 33 publications

Gelation of a Solution of Poly(3-hexylthiophene) Greatly Retards Its Crystallization Rate in the Subsequently Cast Film

Gelation of a Solution of Poly(3-hexylthiophene) Greatly Retards Its Crystallization Rate in the Subsequently Cast Film

Practical applications of small-angle neutron scattering

A Strategy for Revealing the Packing in Semicrystalline π‐Conjugated Polymers: Crystal Structure of Bulk Poly‐3‐hexyl‐thiophene (P3HT)

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