Effect of molecular weight on microcrystalline structure formation in polymer with perylenediimide side chain

Abstract

The effect of molecular weight on the molecular aggregation structure of polymers bearing a pendant perylenediimide (PDI) side chain, designated PAc12PDI, was investigated using synchrotron radiation X‐ray diffraction measurements. It was found that depending on molecular weight, either the main chain axis or the side chain axis behaves as the longitudinal axis in fiber samples and was aligned parallel to the fiber axis. A similar phenomenon is present in thin film samples, but was complicated by the additional influence of the interfacial free energy of the side chain group. Even in the case of the polymer with lower molecular weight, the face plane of PDI was found to show both parallel and perpendicular orientations to the substrate (i.e., flat‐on and edge‐on orientations). On the other hand, if the length of the main chain is sufficiently long with respect to the length of the side chain, the face plane of PDI was oriented perpendicular to the substrate, leading to an edge‐on orientation in the thin film. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 2275–2283

Morphology Changes in Perfluorosulfonated Ionomer from Thickness and Thermal Treatment Conditions

“…It is assumed that I 1 (out-of-plane) and I 2 (in-plane) are both Gaussian distribution functions of the azimuthal angle, φ, shown in Figure S5, with peaks along the meridional (φ = 0°) and equatorial (φ = 90°) directions. I 1 (φ) and I 2 (φ) were then used to determine the normalized integral intensity, I ( q ), which is defined by the following equation …”

A Nanoconfinement Effect Imposed by the Limited End-to-End Distance of the Grafted Chains on a Molecular Aggregation of Polymer Brushes with Crystalline Side Groups

“…Information on the structures perpendicular to the surface was obtained from the in-plane geometry because the scattering vector ( q xy ) was parallel to the surface. In contrast, the detected profiles reflect the crystalline structures parallel to the surface in the out-of-plane geometry. ,,, …”

“…Generally, for polymers with crystalline or liquid-crystalline units in the main chains, the molecular order should be enhanced by increasing the grafting density because of the increased stretching of the chains. , However, if polymer brushes consisting of crystalline or liquid-crystalline side groups are encountered, the molecular aggregation state may exhibit a more complex dependence on the grafting density because the limited end-to-end distance ( d e ) of the tethering chain (i.e., usually below 5 nm) might additionally hinder the organization of the bulky side groups into an ordered superstructure having a size (i.e., 3–6 nm) comparable to d e . Although some works have examined the molecular aggregation state of the side-chain crystalline polymer brushes with varying thickness/molecular weight, − molecular weight distribution, and density of the pendent side groups on the polymer backbones, the effect of grafting density and the associated mechanism have not yet been disclosed.…”

“…In contrast, the detected profiles reflect the crystalline structures parallel to the surface in the out-of-plane geometry. 18,19,44,45 The sum frequency generation (SFG) vibrational spectra of the surfaces of the PODMA brushes were obtained using a customdesigned SFG spectrometer (EKSPLA, Lithuania), as described in previous papers. 46−49 Briefly, a 532 nm visible input beam was generated by frequency doubling the fundamental output from an EKSPLA Nd:YAG laser.…”

Application of Synchrotron Radiation X-ray Scattering and Spectroscopy to Soft Matter

“…Grazing-Incidence Wide-Angle X-ray Scattering with Tender X-rays Organic semiconducting materials have significant potential as flexible, low-cost, and easily processable alternatives to silicon-based semiconducting materials [23]. Polymers with perylenediimide (PDI) pendant side chains, which show crystalline states in thin films, have been paid great attention as n-type semiconducting materials [24][25][26]. The properties of their thin films are closely related to the molecular aggregation state at the surface and interface because the occupancy of surface and interface in the films increases with decreasing film thickness.…”