An ideal stimuli‐responsive controlled/living radical polymerization should have the ability to manipulate the reaction through spatiotemporal “on/off” controls, achieving the polymerization under fully open conditions and allowing for precise control over macromolecular architecture with defined molecular weights and monomer sequence. In this contribution, the photo (sunlight)‐induced electron transfer atom transfer radical‐polymerization (PET‐ATRP) can be realized to be reversibly activated and deactivated under fully open conditions utilizing one‐component copper(II) thioxanthone carboxylate as multifunctional photocatalyst and oxygen scavenger. The polymerization behaviors are investigated, presenting controlled features with first‐order kinetics and linear relationships between molecular weights and monomer conversions. More importantly, “CuAAC&ATRP” concurrent reaction combining PET‐ATRP, photodriven deoxygenation, and photoactivated CuAAC click reaction is successfully employed to synthesize the sequence‐defined multiblock functional copolymers, in which the iterative monomer additions can be easily manipulated under fully open conditions. 相似文献
This study investigated the dependence of the anticorrosion performance of a poly(γ‐glycidoxypropyltrimethoxysilane) (poly(γ‐GPTMS)) sol‐gel coating on AA2024‐T3 aluminum alloy surface state. Two different AA2024‐T3 surface pretreatment procedures were tested: a degreasing with acetone and a chemical multistep etching process (industrial chemical etching pretreatment). Poly(γ‐GPTMS) coatings were deposited onto both pretreated surfaces using the dip‐coating technique. Surfaces were characterized principally by scanning electron microscopy, X‐ray photoelectron spectroscopy, Fourier transform infrared attenuated total reflectance, contact angles, and roughness measurements. Moreover, for the coated AA2024‐T3 surfaces, a pull‐off test was used to evaluate the poly(γ‐GPTMS) adhesion to the pretreated surface. Bare surface properties depended on the applied pretreatment. The chemically etched surface was the roughest and the most concentrated in hydroxyl groups. In addition, comparatively to the degreased surface, it has a more hydrophobic character. Poly(γ‐GPTMS) coating revealed an uneven nature and a poor adhesion once it was deposited onto the degreased surface. Coatings anticorrosion performances were evaluated using electrochemical impedance spectroscopy measurements (EIS). Electrochemical impedance spectroscopy data proved that the sol‐gel coating applied onto the chemically etched surface had better anticorrosion performance. 相似文献
The synthesis of poly(ionic liquid) (PIL) nanoparticles grafted with a poly(N‐isopropyl acrylamide) (PNIPAM) brush shell is reported, which shows responsiveness to temperature and ionic strength in an aqueous solution. The PIL nanoparticles are first prepared via aqueous dispersion polymerization of a vinyl imidazolium‐based ionic liquid monomer, which is purposely designed to bear a distal atom transfer radical polymerization (ATRP) initiating group attached to the long alkyl chain via esterification reaction. The size of the PIL nanoparticles can be readily tuned from 25 to 120 nm by polymerization at different monomer concentrations. PNIPAM brushes are successfully grafted from the surface of the poly(ionic liquid) nanoparticles via ATRP. The stimuli‐responsive behavior of the poly(ionic liquid) nanoparticles grafted with PNIPAM brushes (NP‐g‐PNIPAM) in aqueous phase is studied in detail. Enhanced colloidal stability of the NP‐g‐PNIPAM brush particles at high ionic strength compared to pure PIL nanoparticles at room temperature is achieved. Above the lower critical solution temperature (LCST) of PNIPAM, the brush particles remain stable, but a decrease in hydrodynamic radius due to the collapse of the PNIPAM brush onto the PIL nanoparticle surface is observed.
We fabricate a novel cellulose acetate (CA) ultrafiltration membrane modified by block copolymer F127‐b‐ PDMAEMA, which is synthesized using F127 and DMAEMA via the ARGET ATRP method. Compared to conventional ultrafiltration membranes, the incorporation of both F127 and PDMAEMA can not only readily increase the hydrophilicity of the membrane, but also exhibit stimuli‐responsiveness to temperature and pH. Fourier transform infrared spectroscopy (FT‐IR), nuclear magnetic resonance spectroscopy (NMR), and gel permeation chromatography (GPC) are employed to analyze the structure of the F127‐b‐PDMAEMA. The membrane properties are evaluated via scanning electron microscope (SEM) imaging, porosity test, automatic target recognition Fourier transform infrared spectroscopy (ATR‐FTIR), water contact angle test and permeation test. The results indicate that the F127‐b‐PDMAEMA is an excellent pore agent, which contributes to an enhancement of the membrane in sensitivity to temperature and pH. The modified membrane also exhibits lower water contact angle (64.5°), which is attributed to the good anti‐fouling performance and high water permeation. 相似文献
This review documents the advances in stimuli‐responsive water‐soluble fullerene (C60) polymeric systems. Stimuli‐responsive polymers, when grafted onto C60 impart “smart” and “responsive” characteristics, and these novel materials adopt various morphologies when subjected to external stimuli, such as pH, temperature, and salt. Various synthetic approaches for producing C60‐polymers are outlined and discussed. The responsive behavior, water solubility, and self‐assembly characteristics of these C60‐polymers make them attractive for applications such as drug delivery, temperature sensors, and personal care. 相似文献
Poly(glycidylmethacrylate) (PGMA) brushes were grafted from chloromethylated polysulfone (CMPSF) membrane surface by surface‐initiated atom transfer radical polymerization (SI‐ATRP), and the grafting was followed by hydrolysis of epoxy groups in the grafting chains to improve the membrane's hydrophilic property. Fourier transform infrared spectroscopy (FT‐IR) and X‐ray photoelectron spectroscopy (XPS) measurements confirmed the successful grafting and hydrolysis of PGMA. The grafting degree of the monomer, measured by periodic acid titration and gravimetric analysis, increased linearly with the polymerization time, while the static water contact angle of the membrane grafted with PGMA or hydrolyzed PGMA linearly decreased. In comparison with the PGMA‐grafted membranes, the hydrolyzed PGMA‐grafted membranes possess stronger hydrophilicity as indicated by their contact angle and hydration capacity, and as a result they have an improved antifouling property. Therefore, the control of the hydrophilicity of PSF membrane could be realized through adjusting the polymerization time and transforming the functional groups in the grafting chain. 相似文献