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Pressure‐induced polymerization (PIP) of aromatics is a novel method for constructing sp3‐carbon frameworks, and nanothreads with diamond‐like structures were synthesized by compressing benzene and its derivatives. Here by compressing a benzene‐hexafluorobenzene cocrystal (CHCF), H‐F‐substituted graphane with a layered structure in the PIP product was identified. Based on the crystal structure determined from the in situ neutron diffraction and the intermediate products identified by gas chromatography‐mass spectrum, we found that at 20 GPa CHCF forms tilted columns with benzene and hexafluorobenzene stacked alternatively, and leads to a [4+2] polymer, which then transforms to short‐range ordered H‐F‐substituted graphane. The reaction process involves [4+2] Diels–Alder, retro‐Diels–Alder, and 1‐1′ coupling reactions, and the former is the key reaction in the PIP. These studies confirm the elemental reactions of PIP of CHCF for the first time, and provide insight into the PIP of aromatics. Short‐range ordered H,F‐substituted graphane was obtained by compressing benzene and hexafluorobenzene cocrystals. By using neutron diffraction and GC‐MS, the reaction process and elementary reactions were identified. The reaction process involves [4+2]Diels–Alder, retro‐Diels–Alder, and 1‐1′ coupling reactions, and the Diels–Alder reaction is the key reaction in the polymerization process. [ABSTRACT FROM AUTHOR]

Geometric isomerism in polyacetylene is a basic concept in chemistry textbooks. Polymerization to cis-isomer is kinetically preferred at low temperature, not only in the classic catalytic reaction in solution but also, unexpectedly, in the crystalline phase when it is driven by external pressure without a catalyst. Until now, no perfect reaction route has been proposed for this pressure-induced polymerization. Using in situ neutron diffraction and meta-dynamic simulation, we discovered that under high pressure, acetylene molecules react along a specific crystallographic direction that is perpendicular to those previously proposed. Following this route produces a pure cis-isomer and more surprisingly, predicts that graphane is the final product. Experimentally, polycyclic polymers with a layered structure were identified in the recovered product by solid-state nuclear magnetic resonance and neutron pair distribution functions, which indicates the possibility of synthesizing graphane under high pressure. [ABSTRACT FROM AUTHOR]

Under pressure of 1–100 GPa, unsaturated organic molecules tend to form covalent bond to each other for a negative enthalpy change, which often produces polymeric materials with extended carbon skeleton. The polymerization reactions typically happen in crystal, which promotes the topochemical process. This review summarized the topochemical polymerization processes of several alkynes, aromatics, and alkynylphenyl compounds, including the critical crystal structures before the reaction, bonding process, and the structure of the products. Secondly, this review also summarized the condensation reaction identified in the polymerization process, including the elimination of small molecules such as NH3, etc. [ABSTRACT FROM AUTHOR]

Abstract: A type of bifunctional responsive polymer, poly(N-(2-hydroxyl-tert-butyl) acrylamide) (PHTBAM), having both reactivity and thermosensitivity was synthesized. Such polymer can be considered as a modified poly(N-isopropylacrylamide) (PNIPAM) by introducing hydroxymethyl group at α-position, which possesses responsive behavior similar to PNIPAM, and less dependence of external condition. Moreover, thermal phase transition of this polymer is completely reversible without any hysteresis. LCST of PHTBAM occurs around 23 °C, which can be modulated by copolymerization with more hydrophilic comonomer such as N-hydroxyethylacrylamide (HEAM). The LCST of the P(HTBAM-co-HEAM) copolymer can be adjusted over a wide range by increasing HEAM content up to higher lever, due to the structural similarity between HTBAM and HEAM units without destroying the PNIPAM–type main chain and loss of the response sensibility. In addition, the hydroxyl functional groups at side chain of PHTBAM provide a capability of further chemical modification for a variety of applications in material science and biotechnology. [Copyright &y& Elsevier]

The core-shell structured polyaniline-functionalized-BaTiO3 (BT@PANI) nanoparticles with controllable shell layer thicknesses are developed via in-situ aniline polymerization technology and characterized in detail. The results prove that the PANI shell layer with the adjustable and controllable thicknesses of 3–10 nm are completely stabilized on the surface of the BaTiO3 core. In addition, the BT@PANI nanoparticles are regarded as the hybrid nanofillers to prepare PEN/BT@PANI nanocomposite films with a PEN matrix. The research results indicate that the surface functionalized nanoparticles facilitate the compatibility and dispersibility of them in the PEN matrix, which improves the properties of the PEN/BT@PANI nanocomposites. Specifically, the PEN/BT@PANI nanocomposites exhibit thermal stability, excellent permittivity-frequency, and dielectric properties-temperature stability. Most importantly, the energy density of nanocomposites is maintained at over 70% at 180 °C compared with that at 25 °C. All these results reveal that a new way to prepare the high-performance PEN-based nanocomposites is established to fabricate an energy storage component in a high temperature environment. [ABSTRACT FROM AUTHOR]

Abstract Crosslinked single-component polyarylene ether nitrile (CSC-PEN) composites were fabricated and improved dielectric properties of the CSC-PENs were obtained. Polyarylene ether nitrile was synthesized through the condensation polymerization between hydroquinone, bisphenol A and 2,6-dichlorobenzonitrile, and then terminated with phthalonitriles (PEN-Ph) by reacting with 4-nitrophthalonitrile. Single-component polyarylene ether nitrile (SC-PEN) composites were obtained through the isothermal crystallization at 280, 300, 310, 320 and 340 °C, respectively. The CSC-PENs were prepared through post self-crosslinking of SC-PEN at 320 °C for 2, 4, 6 and 8 h, respectively. The CSC-PENs were characterized by FTIR, UV–Vis, DSC, XRD, POM, SEM and gel content measurements. Results showed that crystallinity and gel fraction of CSC-PENs is higher than 49.0% and 90.0% respectively. In addition, the PEN crystals are wrapped in its crosslinked network. Compared with PEN-Ph, CSC-PENs showed higher dielectric constant and more stable permittivity with the changing of frequency and temperature. The fabrication CSC-PENs provides a new method for the preparation of high temperature dielectrics. Graphical abstract Image 1 Highlights • Crosslinked single-component polyarylene ether nitrile composites are fabricated. • PEN crystals are wrapped in its crosslinked network. • Crystallinity and gel fraction of CSC-PENs are higher than 49.0% and 90.0% respectively. • CSC-PENs showed high dielectric constant and stable permittivity with the changing of frequency and temperature. [ABSTRACT FROM AUTHOR]