Bicontinuous oxide heteroepitaxy with enhanced photoconductivity.

Self-assembled systems have recently attracted extensive attention because they can display a wide range of phase morphologies in nanocomposites, providing a new arena to explore novel phenomena. Among these morphologies, a bicontinuous structure is highly desirable based on its high interface-to-volume ratio and 3D interconnectivity. A bicontinuous nickel oxide (NiO) and tin dioxide (SnO2) heteroepitaxial nanocomposite is revealed here. By controlling their concentration, we fabricated tuneable self-assembled nanostructures from pillars to bicontinuous structures, as evidenced by TEM-energy-dispersive X-ray spectroscopy with a tortuous compositional distribution. The experimentally observed growth modes are consistent with predictions by first-principles calculations. Phase-field simulations are performed to understand 3D microstructure formation and extract key thermodynamic parameters for predicting microstructure morphologies in SnO2:NiO nanocomposites of other concentrations. Furthermore, we demonstrate significantly enhanced photovoltaic properties in a bicontinuous SnO2:NiO nanocomposite macroscopically and microscopically. This research shows a pathway to developing innovative solar cell and photodetector devices based on self-assembled oxides.

Quaternized Sodium Alginate-g-Ethyl-Oxazoline Copolymer Brushes and Their Supramolecular Networks via Hydrogen Bonding.

Novel copolymer brushes of quaternized sodium alginate-g-(2-ethyl-2-oxazoline)n are achieved by the grafting reaction of 2-ethyl-2-oxazoline (EOX) from benzyl bromide groups in quaternized sodium alginate (QSA). The average number of (EOX)n structural units is mediated from 1 to 5 by changing the molar ratio of the EOX monomer to benzyl bromide side groups. There exists obvious microphase separation between the QSA backbone and (EOX)n segments in the copolymer brushes due to their thermodynamic incompatibility. The strong hydrogen-bonding interaction between -OH groups in the backbone and N─C═O groups in (EOX)n segments is helpful for the construction of reversible supramolecular networks. The copolymer brushes show low cytotoxicity for HeLa cells and good antibacterial properties for Escherichia coli and Staphylococcus aureus for the contribution of hydrophilic (EOX)n segments and antibacterial activity of the quaternary ammonium. The antiprotein behavior of polymer surfaces is improved after rearrangement of (EOX)n segments by tetrahydrofuran (THF) vapor induction. These copolymer brushes have good prospects for biomedical applications.

Hemocompatible, biocompatible and antifouling Acylated dextran-g-polytetrahydrofuran graft copolymer with silver nanoparticles: Synthesis, characterization and properties.

The novel amphiphilic acylated dextran-g-polytetrahydrofuran (AcyDex-g-PTHF) graft copolymers have been successfully synthesized via combination of living cationic ring-opening polymerization of tetrahydrofuran (THF) to prepare living PTHF chains with different molecular weights (Mn, PTHF) of 800-2800 g/mol with nucleophile substitution to mediate grafting numbers (GN) of 4-25 per 1000 Dex monosaccharide. The microphase separation in the graft copolymer exists for the incompatibility of hard dextran backbone and soft PTHF branches and the confined crystallization of backbone. This copolymer behaves excellent hemocompatibility with red blood cells, good biocompatibility with HeLa cells and strong resistance to bovine serum albumin adsorption. The microspheres (~1 µm) of graft copolymers loaded with drug ibuprofen exhibit pH sensitive controlled drug release behavior. Moreover, the AcyDex-g-PTHF/Ag nanocomposites show good antibacterial property against E. coli and S. aureus. This novel hemocompatible, biocompatible and antifouling AcyDex-g-PTHF graft copolymer will have potential application in biological and medical fields.

In-situ synthesis of acylated sodium alginate-g-(tetrahydrofuran5-b-polyisobutylene) terpolymer/Ag-NPs nanocomposites.

Sodium alginate (SA) is a marine-derived biocompatible polysaccharide with huge reserves and polyisobutylene (PIB) is a saturated elastomer with gas barrier property, bio-inertness, and biocompatibility. Herein, we developed the biomass-based ASA-g-(THF5-b-PIB) graft copolymer/Ag (3-11 nm, 0.7-3.8%) nanocomposites formed in-situ via combination of transition of terminal groups in PIB chains with grafting-onto method. The above graft copolymers exhibit microphase separation by self-assembly for the difference in chemical structure from backbone and branches and annealing process as well. The crystallization morphology from backbone depends on the Mn,PIB and GN, changing from thin strip to rod-like crystal. The pH sensitivity happens in drug release behavior of ASA-g-(THF5-b-PIB) micelles, which reach 100% of drug-release within 40 h at pH = 7.4. The ASA-g-(THF5-b-PIB)/Ag composites behave good antibacterial properties to both E. coli and S. aureus and anti-protein adsorption performance. This novel graft copolymer with comprehensive properties and would have a prospect in biomedical field.

Cross-Linked Quaternized Poly(styrene-b-(ethylene-co-butylene)-b-styrene) for Anion Exchange Membrane: Synthesis, Characterization and Properties.

Poly(styrene-b-(ethylene-co-butylene)-b-styrene) triblock copolymer (SEBS) was selected for functionalization and cross-linking reaction to prepare the anion exchange membrane. The cross-linked quaternized SEBS (QSEBS-Cn) membranes were synthesized by simultaneous of quaternization and cross-linking of chloromethylated SEBS with α,ω-difunctional tertiary amines. The spacer groups of (-CH2-)n in diamines did affect the functionalization, micromorphology and properties of the resulting QSEBS-Cn membranes. The ionic conductivity of QSEBS-Cn membranes greatly increased and methanol resistance slightly decreased with increasing the length of spacer groups in the cross-linked structures from -(CH2)- to -(CH2)6-. Compared to the un-cross-linked QSEBS, the QSEBS-Cn membranes behaved much higher mechanical property, service temperature, chemical stability and thermal stability. Moreover, the hybrid composite membrane of QSEBS-C6 with 0.5% of graphene oxide could also be in situ prepared. This hybrid membrane had both relatively high ionic conductivity of 2.0 × 10(-2) S·cm(-1) and high selectivity of 7.6 × 10(4) S·s·cm(-3) at 60 °C due to its low methanol permeability.

Ethylene/propylene copolymerization catalyzed by vanadium complexes containing N-heterocyclic carbenes.

Various vanadium complexes containing N-heterocyclic carbenes, VOCl3[1,3-R2(NCH=)2C:] (V1, R = 2,6-Me2C6H3; V2, R = 2,6-Et2C6H3; V3, R = 2,6-(i)Pr2C6H3; V4, R = 2,4,6-Me3C6H2), have been synthesized and employed as catalyst precursors for ethylene/propylene copolymerization after activation by Et3Al2Cl3. Complex V4 showed higher catalytic activity of ca. 38 kg copolymer per (mol of V) per h and an ethylene/propylene copolymer with random monomer distribution could be prepared. Complex V3 consumed more cocatalyst than its analogues to reach higher catalytic activity. The obtained copolymers exhibit relatively narrow polydispersity and contain more randomly distributed monomer units than that the copolymers prepared by using the traditional vanadium catalytic system.

ABA type liquid crystalline triblock copolymers by combination of living cationic polymerizaition and ATRP: synthesis and self-assembly.

Lamellar and hexagonal-coil-cylinder self-assembled structures of ABA type triblock copolymers containing mesogen-jacketed liquid crystalline polymer (MJLCP) as the rod block, and polyisobutylene (PIB) as the coil middle block were discovered. PIB was synthesized by living cationic polymerization of isobutylene initiated by 1,4-bis(2-chloro-2-propyl)benzene (p-DCC), and then a small amount of styrene was introduced at the end of the PIB chains to form the difunctional PIB macroinitiator with -CH2CH(C6H5)Cl end groups for further atom transfer radical polymerization (ATRP). 2,5-Bis[(4-methoxyphenyl)oxycarbonyl]styrene (MPCS) was block-copolymerized from the difunctional PIB macroinitiators at 110 °C. The molecular characterization of the triblock copolymers was performed with 1H NMR, 13C NMR, gel permeation chromatography (GPC), and thermogravimetric analysis (TGA). Their phase structures and transitions were investigated by differential scanning calorimetry (DSC), small angle X-ray scattering (SAXS), and polarized optical microscopy experiments. It was demonstrated that the triblock copolymers formed lamellar structures at moderate rod fractions and hexagonal coil cylinders in the rod matrix at high rod fractions. The d-spacing of the microphase-separated structures was influenced by the liquid crystalline phase of rod-like PMPCS blocks.

[Relationship between left ventricular diastolic function and plasma brain natriuretic peptide concentration during severe pregnancy-induced hypertension syndrome].

OBJECTIVE: To evaluate the relationship between the left ventricular diastolic function and plasma level of plasma brain natriuretic peptide (BNP) among patients with pregnancy-induced hypertension (PIH) syndrome. METHODS: The left ventricular diastolic function was evaluated by Doppler echocardiography, and plasma BNP level was tested by radioimmunoassay among 36 pregnant women with severe PIH, 32 normal pregnant women, and 21 normal non-pregnant women of childbearing age. RESULTS: The parameters such as peak mitral flow velocity in early diastole (E), E-wave velocity-time integral (EVTI), the ratio of peak mitral flow velocity in early diastole and peak A-wave velocity in late diastole (E/A), peak pulmonary venous diastolic forward flow velocity (D) and D-wave velocity-time integral (DVTI) of the 36 severe PIH patients were significantly lower than those of the 32 normal pregnant women and those of the 21 normal non-pregnant women of child-bearing age. But the parameters such as A, A-wave velocity integral (AVTI), and peak pulmonary venous diastolic forward flow velocity (AR) were significantly higher than those of the normal pregnant women and those of the normal non-pregnant women of child-bearing age. E/A ratio, D and DVTI of the normal pregnant women were significantly lower than those of the normal non-pregnant women of child-bearing age, however, A, AVTI, S/D, and AR were significantly higher than those of the normal non-pregnant women of child-bearing age. The BNP concentration of the normal pregnant women was significantly higher than that of the normal non-pregnant women of childbearing age, but significantly lower than that of the severe PIH patients. There were significant correlations between left ventricular diastolic function variables (E/A ratio and AR) and BNP concentration in normal pregnant women and in PIH patients. CONCLUSION: The left ventricular diastolic function is slightly damaged in normal pregnant women and significantly damaged in patients with severe PIH. The plasma BNP level of pregnant women can become an excellent index to predict their left ventricular diastolic function.