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Understanding the deformation mechanism of conjugated polymers is essential for developing flexible or stretchable electronic devices. In this work, the mechanical properties of poly(3-dodecylthiophene) (P3DDT) and poly(3-hexylthiophene) (P3HT) are measured at different temperatures, and the underlying deformation mechanism is explored by using in situ X-ray scattering and pole figure. It is observed that the modulus and fracture strength of P3DDT decrease with increasing stretching temperature. The elongation at break of P3DDT exhibits a sharp increase when the stretching temperature reaches 45 °C. The general deformation process of the two polymers is in line with the traditional deformation mechanism established for flexible crystalline polymers with several special features. Well-defined yielding is not detected even at temperatures below the main-chain glass transition temperature, which corresponds to the microscopic observation of the absence of a well-defined lamellar–fibrillar transition. By anal...

The crystallization of poly(e-caprolactone) (PCL) and isotactic polypropylene (iPP) infiltrated in nanoporous anodic alumina oxide (AAO) templates was reexamined to demonstrate the importance of obtaining polymer-free, clean AAO surfaces on the nucleation, size dependence of crystallization temperature (Tc), and texture. The AAO pore diameters cover a broad range from 400 to 20 nm. When the AAO templates were completely free of any residual polymer on their surfaces, differential scanning calorimetry (DSC) experiments exhibited a single crystallization peak for all the samples with different AAO pore sizes. A drastic decrease in Tc with density of domains indicated a transition from heterogeneous to homogeneous/surface nucleation. A regular decrease of Tc with pore size was observed in the low Tc regime, as a result of the volume dependence of nucleation events. The chain alignment of the two polymers infiltrated in AAO was studied by two-dimensional wide-angle X-ray scattering (WAXS). By comparing the ex...

The structural transitions in solution-cast film of poly[5,5′-bis(2-butyloctyl)-(2,2′-bithiophene)-4,4′-dicarboxylate-alt-5,5′-2,2′-bithiophene] (PDCBT) copolymer have been systematically studied by a combination of differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), in situ Fourier transform infrared spectroscopy (FTIR), UV–vis spectroscopy, and in situ wide-angle X-ray scattering (WAXS). The glass transition temperature of the main chain as well as the melting and crystallization temperatures of the polymer were determined as 10, 238, and 221 °C, respectively. The out-of-plane deformation vibration of PDCBT Cβ–H groups in FTIR has been manifestly assigned for the first time. A broad endothermic peak between 30 and 120 °C was observed during DSC heating process and was attributed to the enthalpic relaxation of the twist glass transition, which resulted in a small negative effect on the power conversion efficiency (PCE) of solar cells. A reorganization process in the crystalline re...