Chain transfer to solvent in BN 2-vinylnaphthalene radical polymerization

The synthesis of vinyl alcohol copolymers is limited due to the poor radical reactivity of vinyl acetate (VAc), the traditional precursor to polyvinyl alcohol (PVA). Main group monomers such as BN 2-vinylnaphthalene (BN2VN) have attracted attention as alternatives to VAc to form side chain hydroxyls via oxidation, but outstanding questions of molecular weight control remain. Herein we report systematic investigation of solvent, temperature, and initiator concentration as factors influencing BN2VN degree of polymerization. We find increased chain transfer to toluene, hypothesized to arise from differences in radical stabilization and reactivity by aromatic and BN aromatic rings. As a result of these combined efforts, high molecular weight (M_w ~ 10⁵ g mol⁻¹) BN2VN homopolymers and BN2VN-styrene copolymers were obtained.     

A Switch in the Hydrophobic/Hydrophilic Gas-Adsorption Character of Prussian Blue Analogues: An Affinity Control for Smart Gas Sorption

Porous coordination polymers are molecule-based materials presenting a high degree of tunability, which offer many advantages for targeted applications over conventional inorganic materials. This work demonstrates that the hydrophilic/hydrophobic character of Prussian blue analogues having a lipophilic feature may be tuned to optimize the gas adsorption properties. The role of the coordinatively unsaturated metal sites is emphasized through a combination of theoretical and experimental study of water, ethanol, and n-hexane adsorption.     

Macromolecular synthesis from saccharic lactones. Ring-opening polyaddition of D-glucaro- and D-mannaro-1,4:6,3-dilactones with alkylenediamines

Ring-opening polyaddition of a saccharic acid dilactone prepared from D-glucose, D-glucaro-1,4 : 6,3-dilactone, with several alkylenediamines proceeded at room temperature with no catalyst. The resulting new polyamides carrying many pendant hydroxyl groups, poly(alkylene D-glucaramide)s, were more amorphous and hydrophilic than the corresponding nylons having no hydroxyl groups, and were hydrolyzed more easily than the latter in an acidic condition. The ring-opening ability of D-mannaro-1,4:6,3-dilactone, which was another saccharic acid dilactone obtained from D-mannitol, was found to be lower than that of the D-glucaric analogue. © 1993 John Wiley & Sons, Inc.     

Ti接枝MCM-41催化剂的结构设计及化学亲和选择性研究

 用二氯化钛茂作为活性物种的来源，利用Si－MCM－41催化剂表面羟基的反应性，得到了Ti接枝MCM－41催化剂的两种结构模型．结构表征结果表明，Ti接枝MCM－41催化剂不仅长程结构好，孔径分布均一，而且催化剂表面活性中心含量高．两种结构模型催化剂上芳烃羟化反应性能表明，Ti接枝MCM－41催化剂表面的亲水／憎水性可以在较宽的范围内调变，从而可实现控制芳烃羟化的化学亲和选择性．另外，研究结果还表明，Ti接枝MCM－41催化剂具有很好的活性稳定性．     

Adsorption of n-Butanol from Aqueous Solutions on a Bi–Ga Electrode

Curves of the differential capacitance at the Bi–Ga/H₂O interface in 0.05 M Na₂SO₄ solutions with different concentrations of n-C₄H₉OH are obtained by a bridge method at 420 Hz and 32°C. Adsorption parameters of n-C₄H₉OH, determined by a regression analysis of these curves, are compared with relevant data for mercury and partially fused polycrystalline bismuth (pBi). That the adsorption behavior of organic molecules at Hg differs from that at pBi and Bi–Ga is due not to their different hydrophilicity but to a different physical interaction water–electrode. The reason for this phenomenon can be an unequal spread of electron density beyond the ionic cores of Hg and Bi. These notions are corroborated by the fact that the Bi–Ga data fit overall correlation dependence between the electronic capacitance of different electrodes in the absence of a chemisorption interaction metal–water and the adsorbability of the n-C₄H₉OH molecules on them.     

Electrical Double Layer on Liquid Sn–Ga Alloy in Aqueous Solutions

Double-layer parameters of a liquid Sn–Ga electrode in aqueous electrolyte solutions are studied. It is shown that Sn in the alloy with Ga is a surface-active component and is forced out onto a surface layer of the electrode. The double-layer parameters of an Sn–Ga electrode (8 at. % Sn), which are measured in the experimentally accessible range of charges, differ radically from the parameters of Ga electrodes and are close to those of Sn electrode. Hence, an Sn–Ga electrode containing 8 at. % Sn simulates electrochemical properties of a liquid Sn electrode. The difference between reciprocal electronic capacitances of Hg and Sn and a corrected electrochemical work function of Sn are determined. It is shown that the chemisorption interaction of an Sn–Ga electrode with water molecules is virtually absent at charges more negative than –7 C/cm². A potential drop on uncharged Sn, which is associated with water chemisorption, is –20 mV. Thus, the hydrophilicity of Sn is slightly higher than that of Hg, Bi–Ga, Pb–Ga, and Tl–Ga and significantly lower than that of In–Ga, Cd–Ga, and Ga.     

Some Aspects of the Mobility and Distribution of Toxic Heavy Metal Contaminants Insoil Profiles and River Sediments

Abstract

Investigations of the distribution and mobility of Pb, Ni, Cd and Hg have shown that Pb is strongly associated with humic substances in the top layer of soils and in river sediments, and that Pb shows the highest organophilicity. Ni is very organophilic, and Cd, somewhat less so. The hydrophilicity of Hg highly influences its movement in soil profiles and river sediments. The risk of contamination by these metals is characterized through the environment protection capacity (EPC_G) values which combine humus content and the quality and thickness of the humus layer in one parameter. The risk of contamination is highest at low EPC_G values. Increase of EPC_G decreases the risk of environmental contamination through binding of heavy metals to humic substances, decreasing their mobility.     

Effect of pH on Poly(acrylic acid) Solution Polymerization

The free-radical redox-initiated aqueous solution polymerization of fully and partially neutralized acrylic acid was carried out at room temperature under full exposure to air. The effect of neutralization degree on the polymerization rate and product properties was studied. Increasing neutralization of the reaction mixture with sodium hydroxide resulted in greater conversion of acrylic acid to sodium acrylate. The rate of polymerization, determined from a gravimetric off-line water removal technique, was shown to decrease significantly with decreasing degree of neutralization. Molecular weight also decreased with decreasing degree of neutralization. The glass transition temperature and hydrophilicity of the polymer product decreased with increasing degree of neutralization. In-line infrared monitoring was also used to monitor the reaction progress and was shown to be an effective tool for this purpose.     

Dual pH‐ and Temperature‐Responsive Metallosupramolecular Block Copolymers with Tunable Critical Micelle Temperature by Modulation of the Self‐Assembly of NIR‐Emissive Alkynylplatinum(II) Complexes Induced by Changes in Hydrophilicity and Electrostatic Effects

Terpyridylplatinum(II)‐based metallosupramolecular triblock copolymers with hydrophilic alkynyl ligands have been synthesised and characterised. As a result of the intrinsic properties of Pluronics, reversible temperature‐induced micellisation occurred at high temperature leading to aggregation of the platinum(II) complex moieties through Pt???Pt and π–π interactions, resulting in significant UV/Vis absorption and near‐infrared (NIR) emission spectral changes. The critical micelle temperatures of the complexes were found to vary from 21 to 30 °C due to differences in the hydrophilicity of the alkynyl ligands and the electrostatic repulsions between the positively charged platinum(II) complex moieties. One of the complexes with pH‐responsive CH₂NMe₂ groups on the alkynyl ligand was found to show NIR emission that is sensitive to both pH and temperature. Such dual‐responsive behaviour has been ascribed to the modulation of the self‐assembly of the complex moieties by temperature‐induced micellisation and the changes in the hydrophilicity as well as electrostatic interactions upon protonation/deprotonation of the CH₂NMe₂ groups on the alkynyl ligand.     

Effects of mussel-inspired co-deposition of 2-hydroxymethyl methacrylate and poly (2-methoxyethyl acrylate) on the hydrophilicity and binding tendency of common hemodialysis membranes: Molecular dynamics simulations and molecular docking studies

Despite advances in the field, hemoincompatibility remains a critical issue for hemodialysis (HD) as interactions between various human blood constituents and the polymeric structure of HD membranes results in complications such as activation of immune system cascades. Adding hydrophilic polymer structures to the membranes is one modification approach that can decrease the extent of protein adsorption. This study conducted molecular dynamics (MD) simulations to understand the interactions between three human serum proteins (fibrinogen [FB], human serum albumin, and transferrin) and common HD membranes in untreated and modified forms. Poly(aryl ether sulfone) (PAES) and cellulose triacetate were used as the common dialyzer polymers, and membrane modifications were performed with 2-hydroxymethyl methacrylate (HEMA) and poly (2-methoxyethyl acrylate) (PMEA), using polydopamine-assisted co-deposition. The MD simulations were used as the framework for binding energy simulations, and molecular docking simulations were also performed to conduct molecular-level investigations between the two modifying polymers (HEMA and PMEA) and FB. Each of the three proteins acted differently with the membranes due to their unique nature and surface chemistry. The simulations show PMEA binds less intensively to FB with a higher number of hydrogen bonds, which reflects PMEA's superior performance compared to HEMA. The simulations suggest PAES membranes could be used in modified forms for blood-contact applications as they reflect the lowest binding energy to blood proteins.