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The development of solventless system for modulating properties of network materials is imperative for the next generation sustainable technology. Utilization of photostimulation is important owing to its spatial and temporal locality, yet designing photoresponsive network materials exhibiting repeatable and dramatic change in their properties remains a challenge. Here, the authors report a photocleavable regenerative network (PRN) linked with photoresponsive hexaarylbiimidazoles (HABIs) synthesized from narrow dispersity star-shaped poly(dimethylsiloxane)s (PDMSs) having 2,4,5-triphenylimidazole end groups. The use of urea anion as a catalyst for ring opening polymerization (ROP) of cyclic siloxane initiated from silanols enables control of molecular weight and dispersity. The rheological measurements for the synthesized PRNs exhibit drastic changes in storage and loss moduli (G' and G″) upon photoirradiation in the solid state (G' > G″). This photocontrolled change in viscoelasticity with retaining solidity enables application of PRNs as a remotely-controlled photo-melt adhesive and photo-scissible string. The developed PRNs will enable a wide variety of applications such as industrially important next-generation sustainable adhesive, sealant, and reversibly-deformable 3D printing materials with their spatially and temporally local manipulability, solventless handleability, and excellent reversibility., (© 2021 The Authors. Advanced Science published by Wiley-VCH GmbH.)

Reduction of the insulating one-dimensional coordination polymer [Cu(abpy)PF 6 ] n , 1 a(PF 6 ), (abpy=2,2'-azobispyridine) yields the conductive, porous polymer [Cu(abpy)] n , 2 a. Pressed pellets of neutral 2 a exhibit a conductivity of 0.093 S cm -1 at room temperature and a Brunauer-Emmett-Teller (BET) surface area of 56 m 2  g -1 . Fine powders of 2 a have a BET surface area of 90 m 2  g -1 . Cyclic voltammetry shows that the reduction of 1 a(PF 6 ) to 2 a is quasi-reversible, indicative of facile charge transfer through the bulk material. The BET surface area of the reduced polymer 2 can be controlled by changing the size of the counteranion X in the cationic [Cu(abpy)X] n . Reduction of [Cu(abpy)X] n with X=Br (2 b) or BAr F (2 c; BAr F =tetrakis(3,5-bis(trifluoromethyl)phenyl)), affords [Cu(abpy)] n polymers with surface areas of 60 and 200 m 2  g -1 , respectively., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Template-free fabrication of non-spherical polymeric nanoparticles is desirable for various applications, but has had limited success owing to thermodynamic favorability of sphere formation. Herein we present a simple way to prepare cubic nanoparticles of block copolymers by self-assembly from aqueous solutions at room temperature. Nanocubes with edges of 40-200 nm are formed spontaneously on different surfaces upon water evaporation from micellar solutions of triblock copolymers containing a central poly(ethylene oxide) block and terminal trimethylene carbonate/dithiolane blocks. These polymers self-assemble into 28±5 nm micelles in water. Upon drying, micelle aggregation and a kinetically controlled crystallization of central blocks evidently induce solid cubic particle formation. An approach for preserving the structures of these cubes in water by thiol- or photo-induced crosslinking was developed. The ability to solubilize a model hydrophobic drug, curcumin, was also explored., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The activation of O2 is a key step in selective catalytic aerobic oxidation reactions mediated by transition metals. The bridging trinuclear palladium species, [(LPd(II))3(μ(3)-O)2](2+) (L=2,9-dimethylphenanthroline), was identified during the [LPd(OAc)]2(OTf)2-catalyzed aerobic oxidation of 1,2-propanediol. Independent synthesis, structural characterization, and catalytic studies of the trinuclear compound show that it is a product of oxygen activation by reduced palladium species and is a competent intermediate in the catalytic aerobic oxidation of alcohols. The formation and catalytic activity of the trinuclear Pd3O2 species illuminates a multinuclear pathway for aerobic oxidation reactions catalyzed by Pd complexes., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The synthesis of N-heterocyclic carbene (NHC) adducts by condensation of diamines with appropriately substituted benzaldehydes is described. This simplified approach provides the NHC adduct without first having to generate the carbene followed by its protection. These adducts undergo thermal deprotection to generate N-heterocyclic carbene in situ. Adduct decomposition temperatures were investigated as a function of catalyst structure by using thermal analysis and spectroscopic techniques. Importantly, unlike adducts derived from chloroform, the new pentafluorobenzene-based adducts are more readily prepared and are stable at room temperature. The utility of these adducts as organic catalyst precursors for living ring-opening polymerization (ROP) of lactide, transesterification reactions, and the synthesis of N-heterocyclic carbene ligated organometallic complexes is also described.

A small variation in the substituent R' on the metallocene catalyst employed in the copolymerization of ethene and propene leads to a highly alternating (81-83%) structure (1) rather than a statistical copolymer. Such copolymers were until recently only accessible by hydrogenation of polyisoprene or 1,4-poly(pentadiene)., (© 1998 WILEY-VCH Verlag GmbH, Weinheim, Fed. Rep. of Germany.)