The dependence of particulate Langmuir–Blodgett (LB) monolayer quality on the surface nature of the substrate was investigated by pretreating the substrates with different methods, and the optimal withdrawal speed was determined by detecting the quality of particulate monolayers deposited at different withdrawal speeds. Furthermore, the effects of stearic acid (SA) concentration on the quality of particulate monolayers were discussed. Results indicated that surface amination would favor the transfer of the floating particulate monolayer from the interface to the substrate, which would be attributed to the formation of chemical bonds between the – NH 2 groups on the substrate surface and the functional groups of – COOH and Si – OH groups on surfaces of particles floating at the interface. And the withdrawal speed of 1 mm ⋅ min -1 was appropriate for the fabrication of high-quality particulate LB monolayer because low withdrawal speed can offer sufficient time to form chemical bonds and expel the subphase from the substrate. Additionally, SEM images illustrated that the SA concentration of 0.40 mg ⋅ mL -1 was suitable for the fabrication of well-ordered particulate LB monolayers composed by the particles of 380 nm.
Jiemei Zhou,Xiang Ying,Daiwen Li,Mingjie Wei,Xiangyue Ye,Yong Wang
Nanoporous polymers are extensively coated on various substrates to deliver optical, permselective, or other functions. However, it remains desired to fast produce uniform nanoporous polymer coatings on substrates with complex surfaces. Herein, by manipulating the interactions between block copolymers and selective solvents, we prepare repairable nanoporous polymers on arbitrary substrates. This is realized by an extremely simple sequential coating process: sequential coating of block copolymers and their swelling agents on substrate surfaces. The swelling agents are comprised of two solvents that swell the constituent blocks of the copolymers to different degrees, rapidly producing polymer coatings with uniform, interconnected, sub-50 nm pores. This sequential coating process is able to conformally build nanoporous polymers on nonplanar substrates with large lateral sizes and complex surface features, and also to in situ repair defects arising during usages. We further demonstrate that the nanoporous coatings show excellent antireflective and membrane separation performances. This sequential coating process is dictated by polymer–solvent interactions, and is expected to find applications in diverse fields for its simplicity, adaptability, and the capability to produce well-defined nanoporosities.
Thin-film composite (TFC) membranes can find broad uses in desalination and wastewater treatment . However, industrialized interfacial polymerization involves many organic solvents and toxic monomers . An aqueous fabrication process can meet the standards of green and sustainable production, but fabricating defect-free thin films in a homogenous phase remains challenging. Herein, we fabricate a series of TFC nanofiltration membranes through a contra-diffusion process based on the cross-linking of metal ions and alginate . The film formation is confined at the ultrafiltration substrate surface due to the competition between reaction and restricted diffusion. Among a series of metal ion/alginate composites, the Cu 2+ /alginate composite membrane displays superior nanofiltration performance because of the strong affinity between Cu 2+ and alginate. The highly negatively charged membrane performs a high rejection to divalent anions and anionic dyes based on the Donnan effect . The effects of alginate concentration and diffusion time on membrane performance were investigated to achieve optimal fabrication conditions. The as-prepared membrane shows a rejection of 96.2% to Na 2 SO 4 with permeation flux around 50.2 L·m −2 ·h −1 under 0.6 MPa, and 99.5% to several dye molecules. Moreover, the membrane performs outstanding anti-fouling and anti-bacterial properties because of its excellent hydrophilicity and the existence of Cu 2+ .
危险品化学品经营许可证（带存储）