Sugar-based micro/mesoporous hypercross-linked polymers with in situ embedded silver nanoparticles for catalytic reduction

• Qing Yin,
• Qi Chen,
• Li-Can Lu and
• Bao-Hang Han

Beilstein J. Org. Chem. 2017, 13, 1212–1221, doi:10.3762/bjoc.13.120

• microporous organic materials with a high specific surface area (SSA) [1][2]. The preparation of HCPs mainly includes three different synthesis strategies, namely postcross-linking of polymeric precursors containing functional groups [3], the “knitting” of rigid aromatic building blocks by external cross

• -linkers [4], and self-polycondensation of small molecular monomers [5]. Since the Tan group proposed the new synthetic strategy that "knits" low functionality rigid aromatic compounds with formaldehyde dimethyl acetal (FDA) as an external cross-linking agent through a Friedel–Crafts reaction to synthesize

Synthesis, structure, and mechanical properties of silica nanocomposite polyrotaxane gels

• Kazuaki Kato,
• Daisuke Matsui,
• Koichi Mayumi and
• Kohzo Ito

Beilstein J. Org. Chem. 2015, 11, 2194–2201, doi:10.3762/bjoc.11.238

• not occur without silica. This suggests that the silica nanoparticles behave as cross-linkers. Viscoelastic measurements of the nanocomposite gels showed no stress relaxation regardless of the silica content for <20% compression strain, indicating an infinite stable network without physical cross

• polymer chains were not directly bonded but rather mechanically interlocked to the silica surfaces. The silica nanoparticles were homogeneously distributed in the gel and worked as cross-linkers to immobilize the cyclic components of the polyrotaxanes on the silica surfaces. As the backbone polymer chains

Synthesis and characterization of a hyper-branched water-soluble β-cyclodextrin polymer

• Francesco Trotta,
• Fabrizio Caldera,
• Roberta Cavalli,
• Andrea Mele,
• Carlo Punta,
• Lucio Melone,
• Franca Castiglione,
• Barbara Rossi,
• Monica Ferro,
• Vincenza Crupi,
• Domenico Majolino,
• Valentina Venuti and
• Dominique Scalarone

Beilstein J. Org. Chem. 2014, 10, 2586–2593, doi:10.3762/bjoc.10.271

• structural aspects and functional properties, and in particular pyromellitic nanosponges were found to present a critical cross-linking value [17]. In other words, the maximum number of cross-linkers per monomer was proved to be around 6 (i.e., 6 mol of pyromellitic dianhydride for each mol of β-CD). If the

N-Alkylated dinitrones from isosorbide as cross-linkers for unsaturated bio-based polyesters

• Oliver Goerz and
• Helmut Ritter

Beilstein J. Org. Chem. 2014, 10, 902–909, doi:10.3762/bjoc.10.88

• ) were used as model systems and reacted with dimethyl itaconate to further characterize the 1,3-dipolaric cycloaddition. Keywords: bio-based polyesters; cross-linkers; dinitrones; 1,3-dipolar cycloaddition; isosorbide; Introduction Nitrones represent a class of compounds with a versatile use as

• synthesis of polymers bearing nitrones as photosensitive material [7][8] was also described. We focused on the preparation of polynitrones as efficient cross-linkers for unsaturated polyesters based on fumaric und maleic acid [9]. In the light of the growing interest in polymers from renewable resources the

• synthesis of bio-based nitrones as novel cross-linkers for unsaturated bio-polyesters [10] offers an interesting access to biocompatible materials. This paper presents the synthesis of bio-based N-alkylated dinitrones based on isosorbide and the subsequent use of these dinitrones as cross-linkers in a 1,3

Polymeric redox-responsive delivery systems bearing ammonium salts cross-linked via disulfides

• Christian Dollendorf,
• Martin Hetzer and
• Helmut Ritter

Beilstein J. Org. Chem. 2013, 9, 1652–1662, doi:10.3762/bjoc.9.189

• or CL 2, or both cross-linkers (Scheme 2). Rheological measurements of cross-linked polymer discs To investigate the rheological characteristics of cross-linked polycationic hydrogels, polymer discs of poly(DEAAm-co-DMAEMA, 1:1) containing between 1.0 and 5.0 mol % of either CL 1 (samples 4), or CL 2

• (samples 5), or both cross-linkers (samples 6) were synthesized. The samples were immersed in distilled water until the equilibrium state of swelling was reached. The swollen samples were then used for oscillatory measurements using the serrated plate–plate geometry. As expected, the storage modulus G

• the enhanced affinity for interactions with water molecules leads to a better enclosure of water and therefore a higher swelling degree. Sample 6, which contains both cross-linkers, shows the lowest values for Q. This can be attributed to its overall higher content of cross-linker, compared to samples

Supramolecular hydrogels formed from poly(viologen) cross-linked with cyclodextrin dimers and their physical properties

• Yoshinori Takashima,
• Yang Yuting,
• Miyuki Otsubo,
• Hiroyasu Yamaguchi and
• Akira Harada

Beilstein J. Org. Chem. 2012, 8, 1594–1600, doi:10.3762/bjoc.8.182

• tertiary gels, which should create a new paradigm in materials science [10]. Polyrotaxanes form topological gels, because the rotor molecules, which act as cross-linkers, slide on the axial polymer chain. In contrast, chemical gels do not exhibit cross-linker slippage. Previously, there have been some

Functionalized copolyimide membranes for the separation of gaseous and liquid mixtures

• Nadine Schmeling,
• Roman Konietzny,
• Daniel Sieffert,
• Patrick Rölling and
• Claudia Staudt

Beilstein J. Org. Chem. 2010, 6, 789–800, doi:10.3762/bjoc.6.86

• reaction. In the following sections it will be shown which cross-linking method, ionic or covalent, will be the most effective to reduce undesired plasticization effects occurring in different separations. Furthermore, different ionic cross-linkers are compared, since it was expected that higher cation