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Mainchain-type polybenzoxazines (PBz) are self-crosslinkable polymers possessing high flexibility of molecular designs and property adjustments. The corresponding crosslinked PBz in different forms, such as films, porous membranes, electrospun fiber mats, have been prepared for various applications. This work aims on functionalization of PBz with amide groups and Meldrum's acid moieties, to bring hydrogen bonding interaction and additional covalent crosslinks to the crosslinked PBz. A bisphenol derivative possessing both MA and amide groups (MA/Am-BP) is synthesized from a biomass-based precursor of 3,4-dihydrocoumarine. MA/Am-BP is utilized as a monomer, together with 4,4′-oxydianiline and formaldehyde, for preparation of amide- and Meldrum's acid-functionalized polybenzoxazine (MA/Am-PBz) and the corresponding crosslinked polybenzoxazine (CR_MA/Am-PBz). The benzoxazine- and Meldrum's acid-involved crosslinking reactions have been investigated with temperature-dependent Fourier transform infrared spectroscopy. CR_MA/Am-PBz has demonstrated film formability and flexibility. In addition to the attractive thermal properties, including a thermal stability of 340 °C, a char yield of 52 wt% at 800 °C, a storage modulus of 1.44 GPa at 50 °C, and a T g of 295 °C, CR_MA/Am-PBz also exhibits a high tensile strength of 97 MPa, which is superior over the data reported to crosslinked polybenzoxazine films. [Display omitted] • Biomass-based 3,4-dihydrocoumarine is used as a precursor in chemical synthesis. • A bisphenol compound containing amide and Meldrum's acid is synthesized. • Functional mainchain polybenzoxazine and crosslinked polybenzoxazine are prepared. • Meldrum's acid mediated ketene chemistry generates additional crosslinking sites. • Flexible crosslinked polymer films with high mechanical strength are reported. [ABSTRACT FROM AUTHOR]

Abstract: A novel approach to preparing polymeric materials using elemental sulfur as a feedstock through the newly developed sulfur radical transfer and coupling (SRTC) reaction is reported herein. Polybenzoxazines with high sulfur contents are prepared using the SRTC reaction with benzoxazine compounds as the radical acceptors. The reactions between elemental sulfur and benzoxazine rings are analyzed with Fourier transform infrared (FTIR), 1H NMR, and 13C DEPT spectroscopies to elucidate the SRTC reaction mechanism. Moreover, the prepared polybenzoxazine–sulfur hybrid materials show attractive repairing properties based on the dynamic S–S linkages. An effective reaction mechanism and the prepared repairable sulfur‐possessing polymeric materials are demonstrated. [ABSTRACT FROM AUTHOR]

ABSTRACT The reactivity between the active species of atom transfer radical addition and the unsaturated groups of graphene oxides (GOs) has been demonstrated in this work. The reaction and the sequential surface-initiated atom transfer radical polymerization provide a convenient approach to anchor various polymer chains and to buildup various polymer architectures, such as linear polymer, V-shape block polymer, multibonded polymer layer, and hierarchical brush-on-layer polymer, on GO sheet surfaces. The chemical structures and morphology of the polymer-modified GOs have been characterized with Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and atomic force microscopy. After organomodification, the GOs exhibit a good dispersion ability in organic solvent over 80 days, amphiphilic characteristics, and temperature-responsive properties. Reduction of the GOs has been performed to result in graphene-like materials showing certain extent of electron conductivities. An effective approach to synthesize GO/polymer hybrid materials possessing various polymer architectures and attractive properties has been developed. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1588-1596 [ABSTRACT FROM AUTHOR]

ABSTRACT A multifunctional ferrocene-modified poly(glycidyl methacrylate) (PGMA-Fc) and a difunctional β-cyclodextrin derivative (bis-CD) has been prepared for the construction of an electrically driven removable and self-healing polymeric materials based on the complexation reaction between ferrocene and β-CD groups. The chemical structures of PGMA-Fc and bis-CD have been characterized with Fourier transform infrared, 1H nuclear magnetic resonance, and X-ray photoelectron spectroscopy. The effects of electrical voltages and medium conductivity on the decrosslinking efficiency of the crosslinked PGMA-Fc/CD polymer have been examined. The PGMA-Fc/CD network has shown removable feature and properties for application as a reworkable crosslinked material. Moreover, the crosslinked PGMA-Fc/CD sample has shown electrically driven self-healing behavior. The self-healing performance could be enhanced with wetting the sample to increase the electrical conductivity. As a result, the material could serve as a self-healing agent for commercial painting products. Preparation and application of a novel and efficient self-healing polymer have been demonstrated. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3395-3403 [ABSTRACT FROM AUTHOR]

Abstract: Poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) multi-bonded carbon nanotube (CNT) (CNT–PPO) was prepared using brominated PPO under the condition of atom transfer radical polymerization. The structure and properties of CNT–PPO were characterized with FTIR, Raman spectroscopy and thermal analyzer. The PPO layer in a thickness of about 4.5nm was observed covering on the side wall of CNT with a high-resolution TEM. The PPO modification warrants the good dispersion of CNTs in PPO in the formation of PPO/CNT nanocomposites, which demonstrated enhanced mechanical properties and increases in electrical conductivity. The developed approach of CNT modification with engineering plastics can be applied to other polymers and preparation of functional polymer/CNT nanocomposites. [Copyright &y& Elsevier]

Nafion chains have been reacted onto graphene oxide (GO) through atom transfer radical addition (ATRA) reaction between the C–F groups of Nafion and the C=C groups of GO. The obtained nanohybrids of GO and Nafion (GO-Nafion) are characterized with Fourier transform Infrared spectroscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy to support the performance of the ATRA reaction between GO and Nafion and the chemical structure of GO-Nafion. Morphological observation on GO-Nafion with transmission electron microscopy and atomic force microscopy further demonstrates the organic-inorganic hybrid nanosheet structure of GO-Nafion. GO-Nafion has been used as a nanoadditive for fabrication of Nafion-based nanocomposite proton exchange membranes for fuel cells. Compared to the neat recast Nafion membrane, addition of GO-Nafion results in a 1.6-folds of proton conductivity to the corresponding nanocomposite PEM. The single cell tests on the nanocomposite PEM also exhibit an about 35–40% increase in the fuel cell performance. [ABSTRACT FROM AUTHOR]

Crosslinked membranes exhibiting in situ crosslinking and micro-cavity generation in membrane fabrication processes have been reported for pervaporation dehydration on methanol aqueous solutions. Meldrum's acid (MA) modified poly(2,6-dimethyl-1,4-phenylene oxide) (PPO-MA) with various MA contents have been synthesized and well characterized with Fourier transform infrared spectroscopy and 1 H nuclear magnetic resonance spectroscopy. PPO-MA polymers could perform thermally-induced self-crosslinking reaction through cycloaddition reaction between ketene groups generated from MA thermolysis reaction. Meanwhile, MA thermolysis reaction evolves CO 2 and acetone molecules which contribute to generation of micro-cavities in the formed membranes. Consequently, compared to the pervaporative separation performance of pristine PPO membrane (permeation flux: 290 g m −2 h −1 ; separation factor: 57) on a 90 wt% methanol solution at 25 °C, the crosslinked PPO-MA membrane shows a separation factor of 809 with a slight decrease in permeation flux to about 226 g m −2 h −1 . Based on the pervaporation separation index (PSI, the product of permeation flux and separation factor), an 11-times enhancement has been achieved. [ABSTRACT FROM AUTHOR]

Threediamine monomers (ethylenediamine, butylenediamine, and p-phenylenediamine) were selected for cross-linking graphene oxide(GO) to prepare composite graphene oxide-framework (GOF) membranesthrough filtration using a pressure-assisted self-assembly technique.The membranes were applied to separate an ethanol–water mixtureby pervaporation. Unmodified GO comprised only hydrogen bonds andπ–π interactions, but after cross-linking it witha diamine, attenuated total reflectance–Fourier transform infraredand X-ray photoelectron spectroscopy demonstrated that the diaminewas chemically bonded both to GO and the membrane support. Moreover,GO hydrophilicity was substantially altered; water contact angle increasedfrom 24.4° to 80.6° (from cross-linking with an aliphaticstructure of diamine to cross-linking with an aromatic structure).Results of X-ray diffraction showed that d-spacingin GOF layers varied from 10.4 to 8.7 Å. For GOFs presoaked in90 wt % ethanol–water, covalent bonds between the layer anddiamine could effectively suppress stretching of d-spacing. Cross-linking with ethylenediamine produced a compositemembrane that exhibited a short interlayer d-spacingand delivered an excellent pervaporation performance at 80 °C:permeation flux = 2297 g/(m2h); water concentration inpermeate = 99.8 wt %. The membrane showed stability during a long-termoperation at 30 °C for 120 h. [ABSTRACT FROM AUTHOR]

Abstract: The molecular design concept of silicon-nitrogen synergistic effect for highly-efficient flame retardants has been demonstrated in the preparation of reactive type flame retardants which exhibits high flame retardation efficiency and property enhancement ability for developments of high performance polymers. In the synthetic route, a benzoxazine-containing triethoxysilane compound is obtained and used as a monomer together with diphenylsilanediol to result in branched benzoxazine-containing polysiloxanes (PBz-PSO) through a 3 + 2 condensation polymerization reaction. The chemical structures and properties of Bz-TES and PBz-PSO compounds have been characterized with Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, and differential scanning calorimetry. PBz-PSO samples are reactive polymers as they possess thermally-reactive benzoxazine groups. Thermally-crosslinking the PBz-PSO samples results in silicon-containing polymers which show high thermal stability and high flame retardancy (limited oxygen index > 45). Addition of 5 wt% PBz-PSO to a conventional benzoxazine resin could simultaneously improve its flame retardancy (passing the UL 94-V0 test) and increase its glass transition temperature from 145 °C to 205 °C. PBz-PSO samples are highly-efficient reactive-type flame retardants for preparation of halogen-free and phosphorus-free polymers. [Copyright &y& Elsevier]

Abstract: A novel route to functionalize polyvinyl alcohol (PVA) onto multi-walled carbon nano-tube (MWCNT) is reported in this work. FTIR, XPS, Raman spectroscopy, and TGA data confirmed PVA grafting onto the MWCNT. The grafted PVA content was estimated to be 25% in the PVA–functionalized MWCNT. A nano-composite consisting of PVA and 0.05% functionalized CNT was successfully prepared using a solution casting method. Water solubility and diffusivity were enhanced in the CNT-containing membranes. The ionic conductivity of the potassium hydroxide (KOH)-doped PVA/CNT membrane was improved by adding the functionalized CNT, which might be ascribed to the ionic channels provided by the CNT. The methanol permeability was suppressed in the CNT-containing sample. The alkali-doped electrolytes were applied in direct methanol alkaline fuel cells. An open-circuit potential and a peak power density of 0.86V and 39mWcm−2 were obtained using a 2M methanol fuel in 6M KOH at 60°C with the PVA/CNT/KOH electrolyte, significantly higher than those without CNT incorporation. [Copyright &y& Elsevier]