Hydroxyl‐terminated hyperbranched aromatic poly(ether‐ester)s: Synthesis, characterization, end‐group modification, and optical properties

Study of the Interfacial Interaction Performance of Branched Bonding Agents and CL-20

Adding bonding agents to the formulation is an effective way to solve the dewetting of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) in the binder matrix. For the design and selection of the structure of a bonding agent suitable for CL-20, a series of branched polyether bonding agents with terminal groups substituted by cyano, ester and hydroxyl functional groups were employed. Contact angle, Fourier transform infrared spectra (FTIR) and X-ray photoelectron spectroscopy (XPS) measurements were performed, and the results were compared with that of common bonding agent, the boron trifluoride triethanolamine complex (TEA·BF3). The results revealed that the nitramine reinforcement of the three polar groups to CL-20 was in the order cyano group > hydroxyl group > ester group. It is proposed that CBPE-10,10 (cyano-terminated branched polyether bonding agent) had the strongest interfacial interaction with CL-20. The adhesion work value was 105.37 mN⋅m-1 and the adhesion degree was 41.04%. The bonding properties of CBPEs/CL-20 were better than those of TEA·BF3/CL-20.

Supramolecular self-assembly of chiral polyimides driven by repeat units and end groups

Complementary aromatic π–π stacking and hydrogen bonding induce time-dependent chiroptical spectroscopic behaviours of l-phenylalaninate-derived chiral polyimide.

Photoresponsive smectic liquid crystalline multipods and hyperbranched azo polymers

Liquid crystalline azobenzene containing triped and tetraped monomers were designed and synthesized and further used as B3 and B4 type monomers to form hyperbranched polymers with tetraethylene glycol as the A2 type comonomer. The mesophase characteristics of the multiarm-star mesogens and hyperbranched polymers were analyzed using various instrumentation techniques like differential scanning calorimetry (DSC), polarized light microscopy (PLM) and variable temperature XRD. The multipod monomers as well as hyperbranched polymers exhibited thermotropic smectic liquid crystalline characteristics with a tendency toward higher ordered smectic LC phases with increased branching. The hyperbranched polymers exhibited lamellar organization even in the as-solvent precipitated powder sample indicating higher extent of nanosegregation. Their potential application as fast switching photochromic materials was highlighted by carrying out isothermal photoswitching experiments in the LC state. Reversible isothermal smectic-isotropic phase transition could be achieved by UV irradiation in <1 s in the multipod monomers, while it required >2 s UV irradiation in the case of the hyperbranched polymers.