One-Pot, High-Yielding, Oxidative Cyclodehydrogenation Route for N‑Doped Nanographene Synthesis

An intramolecular oxidative cyclodehydrogenation via a one-pot process is described, which induces selective C–C bond formation and bromine functionalization. The application of this new route gives rise to a novel family of partially fused, selectively brominated N-doped pyrimidine graphenes

Design of statistical copolypeptides as multipurpose hydrogel resins in 3D printing

Hydrogels possess desirable properties for the additive manufacturing of 3D objects, but a significant challenge is to expand the range of hydrogel feedstocks with defined molecular structure and functionality while retaining mechanical properties. To this end, the design of photopolymerizable copolypeptides, derived from linear or star-shaped architectures which can be tailored to provide control over mechanical properties and associated 3D printing performance, are reported. Based on hydroxy ethyl-L-glutamine and vinylbenzyl-L-cysteine residues, physical crosslinking via β-motif assembly is shown to afford hydrogels with viscoelastic properties that allow their use as resins for direct ink writing (DIW) and/or direct laser writing (DLW). The strategic incorporation of vinyl benzyl units permits rapid photocrosslinking of the self-assembled hydrogels leading to mechanically robust 3D objects. Significantly, copolypeptide architecture directly influences hydrogel resin viscosity, which affords materials with tailorable characteristics for different 3D printing techniques, highlighting the intrinsic versatility of these systems. </p

Design of statistical copolypeptides as multipurpose hydrogel resins in 3D printing

Hydrogels possess desirable properties for the additive manufacturing of 3D objects, but a significant challenge is to expand the range of hydrogel feedstocks with defined molecular structure and functionality while retaining mechanical properties. To this end, the design of photopolymerizable copolypeptides, derived from linear or star-shaped architectures which can be tailored to provide control over mechanical properties and associated 3D printing performance, are reported. Based on hydroxy ethyl-L-glutamine and vinylbenzyl-L-cysteine residues, physical crosslinking via β-motif assembly is shown to afford hydrogels with viscoelastic properties that allow their use as resins for direct ink writing (DIW) and/or direct laser writing (DLW). The strategic incorporation of vinyl benzyl units permits rapid photocrosslinking of the self-assembled hydrogels leading to mechanically robust 3D objects. Significantly, copolypeptide architecture directly influences hydrogel resin viscosity, which affords materials with tailorable characteristics for different 3D printing techniques, highlighting the intrinsic versatility of these systems. </p

Photoswitchable Layer-by-Layer Coatings Based on Photochromic Polynorbornenes Bearing Spiropyran Side Groups

Herein, we present the synthesis of linear photochromic norbornene polymers bearing spiropyran side groups (poly­(SP-R)) and their assembly into layer-by-layer (LbL) films on glass substrates when converted to poly­(MC-R) under UV irradiation. The LbL films were composed of bilayers of poly­(allylamine hydrochloride) (PAH) and poly­(MC-R), forming (PAH/poly­(MC-R))_<i>n</i> coatings. The merocyanine (MC) form presents a significant absorption band in the visible spectral region, which allowed tracking of the LbL deposition process by UV–vis spectroscopy, which showed a linear increase of the characteristic MC absorbance band with increasing number of bilayers. The thickness and morphology of the (PAH/poly­(MC-R))_<i>n</i> films were characterized by ellipsometry and scanning electron microscopy, respectively, with a height of ∼27.5 nm for the first bilayer and an overall height of ∼165 nm for the (PAH/poly­(MC-R))₅ multilayer film. Prolonged white light irradiation (22 h) resulted in a gradual decrease of the MC band by 90.4 ± 2.9% relative to the baseline, indicating the potential application of these films as coatings for photocontrolled delivery systems