Cross-linked Poly Divinylbenzene Research Articles

Ultrathin Semi-Interpenetrating Network Membranes Based on Perfluorinated Sulfonic Acid Resin and Polydivinylbenzene with Declined Hydrogen Crossover for Proton Exchange Membrane Fuel Cell

Ultrathin semi-interpenetrating proton exchange membranes (SIPN PEMs) comprised of conductive perfluorinated sulfonic acid resin (PFSA) and cross-linked polydivinylbenzene (PDVB) have been fabricated. The SIPN PEMs containing both conductive and cross-linked components exhibited better mechanical stability and electrochemical properties than recast PFSA. The SIPN-3 membrane with the lowest IEC 0.8493 mmol g−1 among the three SIPN PEM samples, however, showed the highest proton conductivity, 0.083 S cm−1, and a comparatively low swelling ratio of 10.12% at 80 °C in deionized water. At the same time, the unique structure and lower thickness endowed the membranes with outstanding fuel cell performance due to the decreased proton transfer resistance. The results show that SIPN-3 with 964.6 mW·cm−2 power density was obtained, and the gas crossover current density was only 1.34 mA·cm−2, which was lower than that for the recast PFSA (1.5 mA·cm−2) and Nafion® NC700 (2.75 mA·cm−2). Thus, constructing a semi-interpenetrating network is certified to enhance properties of the membrane prominently, which has the potential to be applied in PEMFC.

Bamboo-like, oxygen-doped carbon tubes with hierarchical pore structure derived from polymer tubes for supercapacitor applications

In this paper, bamboo-like, O-doped carbon tubes with hierarchical pore structure have been fabricated by the direct pyrolysis of dual cross-linked polydivinylbenzene (PDVB) tubes. The bamboo-like, cross-linked PDVB tubes are firstly synthesized by cationic polymerization of divinylbenzene in cyclohexane using BF3/Et2O complex as the initiator. After a secondary cross-linking being imposed by Friedel–Crafts reaction in CCl4 using anhydrous AlCl3 as the catalyst, the obtained dual cross-linked, carboxylic acid functionalized PDVB tubes are directly subjected to pyrolysis, yielding bamboo-like, O-doped porous carbons. The resultant O-doped porous carbon tubes (BCTF-900, pyrolyzed at 900 °C) exhibit a trimodal pore structure (micro-, meso-, and macropores) with a relatively high specific surface area of 595 m2 g−1 and a low total pore volume of 0.37 cm3 g−1. Such bamboo-like carbon tubes display good volumetric capacitive performance (254 F cm−3 at 0.5 A g−1), moderate volumetric energy density (12.9 Wh L−1 at 428 W L−1), and excellent cycling stability (the capacitance retention has remained at 96.9% after 10000 cycles at 2 A g−1). Due to their unique bamboo-like architecture and trimodal pore structure, the PDVB-derived carbon tubes should have widely application prospect.

Cross-linked polymer grafted with functionalized ionic liquid as reusable and efficient catalyst for the cycloaddition of carbon dioxide to epoxides

A series of cross-linked polydivinylbenzene polymers covalently grafted with various (hydroxyl, carboxyl, and amino) functional ionic liquid were fabricated by a simple method and evaluated as heterogeneous catalysts for the synthesis of cyclic carbonates from CO2 and epoxides. The as-fabricated catalysts show good performance across a wide range of epoxides in the absence of solvent and co-catalyst, especially the one that was grafted with hydroxyl ionic liquid. The effects of functional groups in ionic liquid, reaction temperature, initial CO2 pressure, and reaction time on the cycloaddition reaction were investigated. It is suggested that synergetic effect between functional groups and bromide ions facilitates the catalytic reaction. It is noted that the hydroxyl group with moderate hydrogen bonding is more crucial for the cycloaddition reaction than the other groups. In addition, the recycling test showed that the catalyst could be reused for as many as six times without any loss of catalytic activity.

“Arm-First” Synthesis of Core-Cross-Linked Multiarm Star Polyethylenes by Coupling Palladium-Catalyzed Ethylene “Living” Polymerization with Atom-Transfer Radical Polymerization

We report in this article the “arm-first” synthesis of core–shell-structured multiarm polyethylene (PE) star polymers having multiple linear-but-branched PE arms joined at a cross-linked polydivinylbenzene (polyDVB) core. This synthesis is achieved in two steps by coupling two mechanistically incompatible polymerization techniques, Pd-catalyzed coordinative ethylene “living” polymerization and atom-transfer radical polymerization (ATRP). Ethylene “living” polymerization was first carried out using a functionalized Pd–diimine catalyst, [(ArN═C(Me)–(Me)C═NAr)Pd(CH2)3C(O)O(CH2)2OC(O)C(CH3)2Br]+SbF6– (Ar = 2,6-(iPr)2C6H3) (1), to directly synthesize narrow-distributed PE macroinitiators (MIs) containing an end-capping 2-bromoisobutyryl group active for initiating ATRP. Featured with controllable molecular weights at low polydispersity, the PE MIs are employed subsequently in the second step to initiate cross-linking polymerization of divinylbenzene (DVB) via ATRP to obtain the core-cross-linked star polymers. As a demonstration, three PE MIs at different lengths (number-average molecular weight of 7.3, 10.3, and 13.7 kg/mol, respectively) were specifically synthesized and employed for star construction. In the ATRP step, the effects of the various polymerization parameters, including MI concentration, the molar ratio of DVB to MI, and MI length, on the polymerization kinetics, star yield, average arm number, and average molecular weights of the star polymers were investigated systematically. By controlling the polymerization parameters, a range of PE star polymers having narrow-distributed arm lengths (7.3–13.7 kg/mol) and controllable average arm numbers (ca. 5–43 per star) have thus been successfully synthesized. A study on dilution solution properties of these star polymers having various structural parameters reveals their spherical chain conformation and resemblance of rigid spheres and high-generation dendrimers, with their intrinsic viscosity depending primarily on arm length while not on arm number or polymer molecular weight.

The potential of molecular chemical analysis by high-performance liquid chromatography using a polymeric sorbent based on highly cross-linked polydivinylbenzene

The potential of molecular chemical analysis by high-performance liquid chromatography using a polymeric sorbent based on highly cross-linked polydivinylbenzene

Formation mechanism of micron-sized monodispersed polymer particles having a hollow structure

Recently, the authors reported that micron-sized monodispersed cross-linked polymer particles having a single hollow in the inside were produced by seeded polymerization for the dispersion of (toluene/divinylbenzene)-swollen polystyrene (PS) particles prepared utilizing the dynamic swelling method which the authors had proposed. In this article, the particles at various conversions of the seeded polymerization were observed with an optical microscope in detail. From the obtained results, the formation mechanism of the hollow structure is suggested as follows. As seeded polymerization proceeds, polydivinylbenzene (PDVB) molecules precipitated in the swollen particle are trapped near the interface and gradually pile at the inner surface, which results in a cross-linked PDVB shell. PS which dissolves in the swollen particles is repelled gradually to the inside. After the completion of the polymerization, toluene in the hollow evaporates by drying, and PS clings to the inner wall of the shell uniformly.

Enhancing the anion separations on a polydivinylbenzene-based anion stationary phase

A new anion-exchange stationary phase is described for the separation of inorganic anions by ion chromatography. This stationary phase is made of polydivinylbenzene (P-DVB) based resin with dimetylethanolamine functional groups. The highly cross-linked P-DVB backbone makes this material chemically and mechanically stable under extreme chromatographic conditions. It withstands organic solvents and is stable at a wide range ofpH, temperature and pressure. The separation of anions on this stationary phase can be enhanced by simple modification of the chromatographic conditions. The resolution and peak shape can be improved by adding organic additives to the eluent. These improvements can also be achieved by changing the column operating temperature. This stationary phase is useful for the separation of inorganic anions by suppressor-based and single-column ion chromatography methods.