Recyclability of Photoinduced Cross-Linked EPM Rubber with Anthracene-Grafted Groups:Problems and Their Solutions

In this paper, we present the formation of reversible covalently cross-linked networks in ethylene propylene rubber with grafted anthracene groups (EPM-g-AN) based on the principles of photoinduced anthracene dimerization. First, an industrial-grade EPM rubber grafted with maleic anhydride functional groups (EPM-g-MA) was modified with 9-anthracenemethanol. By irradiating EPM-g-AN with UV light (365 nm), the anthracene moieties dimerize via [4 + 4]cycloaddition, forming a covalent network. The network cleavage proceeds at high temperatures (>170 °C), even if with considerable (chemical) degradation. Furthermore, one of the degradation routes has been identified by 1H NMR to occur via the ester bond cleavage releasing 9-anthracenemethanol. Nevertheless, the reversibility of cross-linking has been achieved by performing the reverse reaction in decalin. The UV-vis spectroscopy clearly shows that the de-cross-linking process in these conditions is due to the anthracene dimer cleavage. Although the recovery in mechanical properties upon recycling is yet to be optimized, the disclosed results pave the way toward the use of anthracene chemistry in thermally reversible networks with possible industrial perspective applications

Polymerization of the new double-charged monomer bis-1,3(N,N,N trimethylammonium dicyanamide)-2-propylmethacrylate and ionic conductivity of the novel polyelectrolytes

The achievement of high ionic conductivity in single-ion conducting polymer electrolytes is one of the important aims for various electrochemical devices including modern lithium batteries. One way to enhance the ionic conductivity in polyelectrolyte systems is to increase the quantity of charge carriers in each monomer unit. Highly charged poly(bis-1,3(N,N,N-trimethylammonium)-2-propylmethacrylate) with one of the most conducting anions, namely dicyanamide, was prepared via free radical bulk polymerization or using ionic liquids as reaction medium. The cationic polymers of the double-charged monomer have molar masses up to equation image = 1,830,000 g/mol and the ionic conductivity equal to 5.51 × 10−5 S/cm at 25°C. The film forming ability, crystallinity, thermal stability, and glass transition temperatures of the new polymeric ionic liquids obtained from detailed studies are presente

Recycling behavior of thermoreversibly Diels-Alder crosslinked EPM

The recyclability of thermoreversibly Diels-Alder (DA) crosslinked EPM has been studied. The retro DA reaction dominates over the dehydration-aromatization process of theDAadduct. Moreover, a negative influence of air occurred as a result of a crosslinking in air flow. Nevertheless, rubber compounds prepared from EPM-g-furan and carbon black can be recycled several times without losing mechanical strength, a feature attributed to a strong antioxidant effect of the carbon black

Nature Chooses Rings: Synthesis of Silicon-Containing Macrocyclic Peroxides

The reactions of 1,2-bis­(dimethylchlorosilyl)­ethane (<b>1</b>), 1,2-bis­(dimethylchlorosilyl)­ethene (<b>6</b>), and 1,2-bis­(dimethylchlorosilyl)­ethyne (<b>7</b>) with <i>gem</i>-bis­(hydroperoxides) <b>2a</b>–<b>h</b> and 1,1′-bis­(hydroperoxy)­bis­(cycloalkyl)­peroxides <b>4a</b>–<b>c</b> were found to proceed in an unusual way. Thus, the reactions do not give the expected polymeric peroxides; instead, they produce cyclic silicon-containing peroxides containing 2, 4, or 6 silicon atoms in the ring: 9- (<b>3a</b>–<b>h</b>), 12- (<b>5a</b>–<b>c</b>), 18- (<b>8</b>,<b> 12</b>), 24- (<b>9</b>, <b>10</b>), 27- (<b>13</b>), and 36-membered (<b>11</b>) compounds. The size of the rings produced in the reactions increases in the series 1,2-bis­(dimethylchlorosilyl)­ethane < 1,2-bis­(dimethylchlorosilyl)­ethene < 1,2-bis­(dimethylchlorosilyl)­ethyne. The resulting 9- and 12-membered cyclic peroxides are stable under ambient conditions. These compounds were isolated by chromatography and characterized by ¹H, ¹³C, and ²⁹Si NMR spectroscopy, X-ray diffraction, elemental analysis, and high-resolution mass spectrometry. The yields vary from 77 to 95%. Structures of the larger-size rings (18-, 24-, 27-, and 36-membered peroxides) were confirmed by ¹H, ¹³C, and ²⁹Si NMR spectroscopy using 2D (COSY, HSQC, and HMBC), 2D DOSY ¹H, 3D ¹H–²⁹Si HMBC-DOSY NMR experiments, and elemental analysis