Novel copolymers based on acrylamide （AM） and complex pseudorotaxane monomer N＇-（3-vinylbenzyl）-l,4- diaminobutane dihydrochloride with cucurbit[6]uril （CB[6]） （3VBCB） were prepared via free-radical polymerization in aqueous solution, and characterized by XH-NMR, FT-IR, elemental analysis and static light scattering. The compositions of the copolymers （PAM3VBCB） with pseudorotaxane units were determined by 1H-NMR and elemental analysis. Thermal properties of the copolymers were studied by TGA, and the effects of the copolymer concentration and pH on the average hydrodynamic radius （Rh） of the copolymer molecules were studied by dynamic light scattering （DLS）. The experiment data show that CB[6] beads are localized on 1,4-diaminobutane units in side chains of the copolymers. TGA results show that thermal stability of the copolymer increases with increasing the content of pseudorotaxane unit because of the enhanced rigidity and the bulky steric hindrance of 3VBCB in side chains of PAM3VBCB. DLS data show that the average hydrodynamic radius of copolymer molecules increases with the increase in the copolymer concentration, and both the pH and electrical conductivity of PAM3VBCB solutions demonstrate an acute change with addition of NaOH because of CB[6] dethreading from the side chains of PAM3VBCB. CB[6] threading and dethreading of PAM3VBCB could be controlled by addition of BaC12 and Na2SO4.
Sodium sulfate as an electrolyte additive was studied via electrochemical methods including linear sweep voltammetry（LSV）, cyclic voltammetry（CV） and electrochemical impedance spectroscopy（EIS） to deeply understand its effect on the hydrogen evolution current and overpotential as well as the formation and structure of anodic passi- vation films on lead surface during the redox processes. The results achieved will be valuable to improve the cycle life and maintenance-free properties of lead-acid batteries.
YU Jin-yu QIAN Zhao-hong ZHAO Meng WANG Yu-jie NIU Lin
A new pH-responsive block copolymer, methoxy poly（ethylene glycol）-b-poly[5-methacrylamido- pentylamine hydrochloride]（mPEG-b-PMAAPA） was synthesized and characterized in this paper. The monomer 5-methacrylamido-pentylamine hydrochloride（MAAPA） and the macroinitiator（mPEG-ACVA） were synthesized, re- spectively, and mPEG-b-PMAAPA was then obtained by free radical polymerization. The structure and molecular weight of mPEG-b-PMAAPA were cont]rmed by hydrogen nuclear magnetic resonance（~H NMR） spectroscopy and gel permeation chromatography with multiangle laser light scattering（GPC-MALLS） measurements. At a low pH, it is hydrophilic due to the protonation of the primary amine groups. With increasing pH value, deprotonation occurs and the hydrophobicity of PMAAPA block increases. This molecular feature leads to interesting aggregation behavior of mPEG-b-PMAAPA in aqueous solutions at different pH values as revealed by dynamic light scattering（DLS） measurements, transmission electron microscopy（TEM） observations and resonance light scattering（RLS） measure- ments.
WANG HongZHU Yue-junREN Xiao-naZHANG HongTAN Ye-bang
Novel dual-responsive superhydrophobic hybrid materials,ZnO/SAMs(self-assembled monolayers)of ionic liquids(ILs)with different counter-anions(I-,BF4-,PF6-and Tf2N-),were synthesized and characterized.ZnO nanoparticles were first deposited on glass surfaces to produce roughness.Next,SAMs of fluorinated-alkyl-3-(3-triethoxysilylpropyl)-4,5-dihydro-imidazoliumiodide(abb.[C8Ftespim]I)were grafted onto these surfaces via-Si-O-covalent bonds using self-assembly technique.The Iion could be subsequently exchanged with BF4-,PF6-or Tf2N-through a simple aqueous anion-exchange reaction.The ZnO/ILs hybrid layers were characterized by atomic-force microscopy(AFM),scanning-electron microscopy(SEM)and X-ray photoelectron spectroscopy(XPS).Their wettability was estimated through the measurements of static and dynamic contact angles(CAs).Compared to corresponding films of ZnO/[C8Ftespim]I with CAs 140.7°±2.0°,films of ZnO/[C8Ftespim]PF6 and ZnO/[C8Ftespim]Tf2N showed CAs with 154.0°±2.0°and 152.0°±2.0°,respectively that remained for a long time.This result suggests that anion-exchange can afford superhydrophobic materials.In addition,the wettability of ZnO/[C8Ftespim]X hybrid layers can be reversibly switched by altering ultraviolet(UV)irradiation and dark storage,which shows a photo-induced reversible switch of wettability.The synergistic action of ZnO nanoparticles and SAMs of ILs produced light-anion dual-responsive superhydrophobic materials with ideal stability.
A fluorescent pyrene derivate, N-allyl-l-pyrenemethylammonium hydrochloride （APA＊）, was reported to form a stable host-guest complex with cucurbit[8]uril （CB[8]）, and this property can be utilized to determinate the purity of CB[8] via emission titration. Moreover, the 1：1 complex of APA and CB[8] can further bind methyl viologen （MV^2＋）, which is the main ingredient of a widely used herbicide, providing a good method to detect MV^2＋, especially at low concentrations.
We report layer-by-layer (LbL) assembly of TiO2 and H4 SiW12 O40 (SiW 12 ) multilayer film on silicon wafers and glass slides for photocatalytic degradation of methyl orange (MO). The photocatalytic efficiency of the obtained multilayer film increases along with the decrease of pH and salt concentration of the incubation solution. The results show that MO can be almost removed in pH2.0 solution without salt addition in the first 60 min incubation when MO concentration is lower than 15 mg/L. Different salts show an apparent inhibitory effect on photocatalytic degradation of MO with the order of ZnCl2 >KCl> NaCl>LiCl. The TiO2 /SiW12 multilayer film maintains photocatalytic activity even after five degradation cycles. The reaction of MO photodegradation accords with an apparent first-order dynamics.
