Coherent crystal branches: the impact of tetragonal symmetry on the 2D confined polymer nanostructure

Abstract

The symmetry of polymer crystals greatly affects the optical, thermal conductivity and mechanical properties of the materials. Past studies have shown that the two-dimensional (2D) confined crystallization of polymer nanorods could produce anisotropic structures. However, few researchers have focused on understanding confined nanostructures from the perspective of crystal symmetry. In this research, we demonstrate the molecular chain self-assembly of tetragonal crystals under cylindrical confinement. We specifically selected poly(4-methyl-1-pentene) (P4MP1) with a 41 or 72 helical conformation (usually crystallizing with a tetragonal lattice) as the model polymer. We found a coherent crystal branching of the tetragonal crystal in the P4MP1 nanorods. The unusual 45°- and 135°-{200} diffractions and the meridional 220 diffraction (from 45°-tilted crystals) have shown a uniform crystal branching between the a 1-axis crystals and the 45°-tilted crystals in the rod long axis, which originates from a structural defect associated with tetragonal symmetry. Surprisingly, this chain packing defect in the tetragonal cell can be controlled to develop along the rod long axis in 2D confinement.

Influence of crystal orientation on stretching induced void formation in poly(4‐methyl‐1‐pentene) investigated by in‐situ small‐angle and wide‐angle X‐ ray scattering

“…These diffractions were assigned to (001), (200), (220), (3 1), (2 2), (3 1), (4 1), and (420) crystal planes of Form I considering their two‐theta value. For the sample without any treatment, the intensity distribution of the diffraction indicates an anisotropic structure in the sample 40 . As T h was higher than 236°C, the intensity distribution of the diffraction was changed obviously from a combination of arc and circle to full circle with increasing T h , indicating a transition of orientation from oriented to randomly distributed one.…”

“…For the sample without any treatment, the intensity distribution of the diffraction indicates an anisotropic structure in the sample. 40 As T h was higher than 236 C, the intensity distribution of the diffraction was changed obviously from a combination of arc and circle to full circle with increasing T h , indicating a transition of orientation from oriented to randomly distributed one.…”

IndiumKα radiation from a MetalJet X-ray source: the long way to a successful charge-density investigation

“…It was shown that this source can be used to provide gallium (9.3 keV) or indium (24.2 keV) K radiation (Otendal et al, 2008;Larsson et al, 2011). However, only the softer gallium radiation has been used for structure determination by singlecrystal X-ray diffraction experiments so far (Chan et al, 2018;Klein et al, 2017;Liang et al, 2021;Mehr et al, 2020;Pan et al, 2017). Initial experiments showing that diffraction data can also be obtained with indium radiation have been reported recently in a PhD thesis (No ¨thling, 2021).…”

Bis(benzoxazol-2-yl)methanides in main group organometallic syntheses and enquiry-based education

“…[51] Since its introduction, the MetalJet X-ray source has been used in single crystal X-ray diffraction studies involving all kinds of different compounds. From small organic molecules [59][60][61][62][63][64] to proteins, [65][66][67][68] polymers [69,70] and metal organic frameworks. [71] Furthermore inorganic compounds containing p-block elements [72,73] as well as d-metal complexes [74][75][76][77][78][79][80] have been investigated.…”