A series of well-defined all-acrylic poly(hydroxyethyl acrylate)-poly(isobornyl acrylate) (PHEA-PIBOA) diblock copolymer nano-objects were prepared by photoinitiated polymerization-induced self-assembly (photo-PISA) of isobornyl acrylate in ethanol/water at 40 °C using poly(hydroxyethyl acrylate)-based macromolecular chain transfer agents (macro-CTAs). Polymerizations proceeded rapidly upon exposure to visible light irradiation (λmax = 405 nm, 0.46 mW cm−2) with high monomer conversion being achieved within 30 min. Gel permeation chromatography (GPC) demonstrated that good control was maintained throughout the photo-PISA process, and the final block copolymers exhibited relatively low polydispersities (Mw/Mn ≤ 1.55). By virtue of the high Tg value of PIBOA, a diverse set of block copolymer nano-objects having different morphologies (e.g. spheres, worms, and vesicles) were prepared and characterized by conventional transmission electron microscopy (TEM). Two phase diagrams were constructed by varying the DP of the PIBOA block or monomer concentration or the DP of the PHEA macro-CTA. Worm-like micelles were prepared by monitoring the viscosity of the reaction mixture in a proof-of-concept experiment. Finally, poly(acrylic acid) (PAA) and poly(2-(dimethylamino)ethyl acrylate) (PDMAEA) macro-CTAs were also utilized to mediate the photo-PISA process, demonstrating the versatility of this method.
Due to its high refractive index, photocatalytic activity, and photoinduced superhydrophilicity, TiO 2 has advantages in photonic crystals (PCs). However, the composite of TiO 2 and PCs needs to be calcined at high temperatures, and the structural stability of the composites is poor. In this study, photoinduced superhydrophilic TiO 2 –poly(hydroxyethyl acrylate)/polystyrene (PHEA/PS) PC composites with strong structural colors and self-cleaning are fabricated by coating triethanolamine-modified anatase TiO 2 nanoparticles-hydroxyethyl acrylate on the surface of PS PCs. The ordered arrays can be retained after the superficial layers of PS PCs are filled with TiO 2 –PHEA, and vivid blue, green, and red composites can be obtained. The water contact angles of the composites can be reduced to 3° in 0.4 s, and superhydrophilicity can be maintained for 180 days in a laboratory environment. The declining superhydrophilicity can be restored under UV irradiation. The composites can degrade the adsorbed methylene blue under UV irradiation. Photocatalytic activity and superhydrophilicity impart self-cleaning ability on the composites. The locking of PS arrays by TiO 2 –PHEA enhances the structural stability of the composites, making them resistant to water soaking and washing. Therefore, the composites show prospects for decoration, fabric coloring, and wearable electronic devices.
Peichao Zhang,Jing Gao,Haiyang Zhang,Yongzhen Wang,Zhen Liu,Sang Yup Lee,Xiangzhao Mao
Zosteric acid (ZA) is a Zostera species-derived, sulfated phenolic acid compound with antifouling activity and has gained much attention due to its nontoxic and biodegradable characteristics. However, the yield of Zostera species available for ZA extraction is limited by natural factors, such as season, latitude, light, and temperature. Here we report the development of metabolically engineered Escherichia coli strains capable of producing ZA from glucose and glycerol. First, intracellular availability of the sulfur donor 3′-phosphoadenosine-5′-phosphosulfate (PAPS) was enhanced by knocking out the cysH gene responsible for PAPS consumption and overexpressing the genes required for PAPS biosynthesis . Co-overexpression of the genes encoding tyrosine ammonia-lyase, sulfotransferase 1A1, ATP sulfurylase, and adenosine 5′-phosphosulfate kinase constructed ZA producing strain with enhanced PAPS supply. Second, the feedback-resistant forms of aroG and tyrA genes (encoding 3-deoxy- d -arabinoheptulosonate 7-phosphate synthase and chorismate mutase , respectively) were overexpressed to relieve the feedback regulation of L- tyrosine biosynthesis. Third, the pykA gene involved in phosphoenolpyruvate-consuming reaction, the regulator gene tyrR , the competing pathway gene pheA , and the ptsHIcrr genes essential for the PEP:carbohydrate phosphotransferase system were deleted. Moreover, all genes involved in the shikimate pathway and the talA , tktA , and tktB genes in the pentose phosphate pathway were examined for ZA production. The PTS-independent glucose uptake system, the expression vector system, and the carbon source were also optimized. As a result, the best-performing strain successfully produced 1.52 g L −1 ZA and 1.30 g L −1 p -hydroxycinnamic acid from glucose and glycerol in a 700 mL fed-batch bioreactor .
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