Characterization and Structural Analysis of Solution-Grown Polyacrylonitrile-co-Methacrylic Acid (PAN-co-MAA) Single Crystals

Abstract

To date studies regarding the growth and characterization of polyacrylonitrile (PAN)-based polymer single crystals have been limited. Polyacrylonitrile-co-methacrylic acid (PAN-co-MAA) was used in this work, which outlines the conditions for three major types of solution-grown crystals. Electron microscopy and diffraction are used to provide a comprehensive study for chain arrangement and growth characteristics for all crystal morphologies. The three major morphological types included polyhedral and polygonal (i.e., parallelogram and elongated rhombus) crystals. Lower crystallization temperatures (65 °C) resulted in more even growth along all facets, while crystals formed at both intermediate (75 °C) and higher (85–95 °C) temperatures exhibited preferential growth along a specific growth plane. Overall crystal size also increased with elevated crystallization temperature (T c ). On the basis of the experimental d-spacing measured by electron diffraction for the (h00) and (0k0) planes, the crystal unit cell lattice constants along a and b axes are found to be a o = 1.023 ± 0.003 nm and b o = 0.612 ± 0.003 nm. This study also examines irradiation sensitivity as it pertains to lattice imaging for these single crystals.

Polymer Interphase Self‐Reinforcement and Strengthening Mechanisms in Low‐Loaded Nanocomposite Fibers

“…The modulus value for the interphase region is based on the assumption that the interphase polymer consists of highly ordered (i.e., crystalline and/or constrained state) chains. Previous work has shown that in the near vicinity of the nC fillers, the polymer chains tend to be highly oriented and aligned in fiber composites . The proximity of the filler and polymer chains at the interphase region also reduces the chain motion, and this phenomenon can be probed experimentally using dynamic mechanical analysis (DMA).…”

“…It was recognized from previous studies that the polymer chains in the near vicinity of the nC filler exhibit conformational distinctions from the bulk matrix . These regions form as a result of interfacial polymer‐nC interactions and lead to the formation of interphase zones in the composite . Effective interfacial interactions and stress transfer between the nanofiller and polymer are also essential for improved mechanical performance in the composite .…”

“…Effective interfacial interactions and stress transfer between the nanofiller and polymer are also essential for improved mechanical performance in the composite . In some cases, these interactions could contribute toward induced interfacial crystallization of polymer by the nanofiller (e.g., polyacrylonitrile and polyvinyl alcohol (PVA) . For such composites, it has been found that the mechanical properties typically exceed the predicted limits based on traditional theories.…”

Structure and topography of thermally reduced graphene oxide reinforced poly(vinyl alcohol‐g‐acrylonitrile) films and study of their mechanical and electrical behavior

“…The observed increase in tensile strength and Young's modulus with increasing TRGO content may be explained by the fact that the PVA‐ g ‐PAN chains in the near vicinity of the TRGO exhibit conformational distinctions from the bulk matrix . These regions are formed as a result of interfacial (PVA‐ g ‐PAN)–TRGO interactions and lead to the formation of interface zones in the nanocomposite . These developed zones enable effective interracial interaction and stress transfer between the grafted copolymer and TRGO thus improving the mechanical performance of the materials.…”

Studying the Dependency of Interfacial Formation with Carbon Nanotube

“…Therefore filler dispersion and/or distribution non-uniformity are expected to play the dominant role in this property trend. Since the nC can affect polymer chain arrangement due to interactions between both components, 6,21,28 these interfacial interactions lead to the formation of an ordered interphase region. The presence of this interphase region is known to contribute greatly to the mechanical performance of the composite.…”