Hierarchically porous carbon is synthesized from PET using ZnCl2/NaCl, exhibiting a high evaporation rate (1.68 kg m−2 h−1) and energy conversion efficiency (97%).
Amphiphilic block copolymers containing polypeptides can self-assemble into a variety of nonspherical structures arising from strong interactions between peptide units. Here, we report the synthesis of a pH-responsive poly(ethyl glycol)-block-poly(l-glutamic acid)-block-poly(N-octylglycine) (PEG-b-PGA-b-PNOG) triblock copolymers by sequential ring-opening polymerization using amine-terminated poly(ethyl glycol) as the macroinitiator followed by selective deprotection of the benzyl protecting group. The obtained triblock copolymer can be directly dispersed in aqueous solution with hydrophilic PEG, pH-responsive PGA block, and hydrophobic PNOG. We present a systematic study of the influence of pH, molar fraction, and molecular weight on the self-assemblies. It was found that the PEG-b-PGA-b-PNOG triblock tends to form two-dimensional nanodisks and nanosheet-like assemblies. The nanodisk-to-nanosheet transition is highly dependent on the pH and molar fraction despite the different molecular weights. We demonstrate that the dominant driving force of the nanodisks and nanosheets is the hydrophobicity of the PNOG blocks. The obtained bioinspired 2D nanostructures are potential candidates for applications in nanoscience and biomedicine.
Ice templating is a versatile strategy for structural engineering of hydrophilic polymers and composites, yet the removal of ice templates requires lengthy lyophilization, and the prepared materials need further crosslinking for use in water. This study introduces an ice-dissolving-complexation (IDC) method to prepare ice templating monolith in an hour without the need for ice sublimation under a vacuum. The aqueous solution of sodium carboxymethyl cellulose (CMCNa) is frozen, immersed in ethanol/Cu 2+ bath (−20 °C). Ice templates dissolved in ethanol, whereby the CMC-Cu 2+ complexation occurred simultaneously to stabilize CMC microstructures. The IDC method enables the preparation and stabilization of CMC monolith with pores and/or aligned channels in one step that is 30-50 times more efficient than lyophilization in terms of the time consumed for ice removal. The IDC method is applicable to various polyelectrolytes and hybrids for straightforward use in water, as exemplified by a proof-of-concept CMC-Cu 2+ -carbon nanotubes monolith, which exhibits high performance solar-steaming under one sun irradiation.
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