Synthesis of poly(4-vinyl pyridine-b-methyl methacrylate) by MAMA-SG1 initiated sequential polymerization and formation of metal loaded block copolymer inverse micelles

Well-defined poly(4-vinylpyridine) (P4VP) was synthesised by nitroxide-mediated radical polymerization using the BlocBuilder MAMA-SG1. The controlled character of the polymerization was confirmed by kinetic measurements and linear increase of the molar mass with monomer conversion. Poly(4-vinylpyridine) terminated with SG1 was then used as macroinitiator and chain extended to form poly(4-vinylpyridine-b-methyl methacrylate) and poly(4-vinylpyridine-b-(methyl methacrylate-co-styrene)) block copolymers. These block copolymers spontaneously organized into spherical inverse micelles in THF with critical micelle concentrations of 0.1 mg/mL for poly(4VP₁₉₀-b-MMA₉₁) and 0.01 mg/mL for poly(4VP₁₉₀-b-(MMA₅₇-co-S₁₈)) and sizes of 70 and 130 nm (DLS), respectively. The inverse micelles were loaded with copper(II)acetate leading to a slight increase in micelle size. The uniform structure of the inverse micelles was confirmed by FeSEM images, while the presence of copper in the micelle core was established by energy-dispersive X-ray spectroscopy (EDX) and FTIR spectroscopy.     

Kinetics of the diazotization and azo coupling reactions of procaine in the micellar media

The kinetics of the diazotization reaction of procaine in the presence of anionic micelles of sodium dodecyl sulfate (SDS) and cationic micelles of cetyltrimethyl ammonium bromide (CTAB), dodecyltrimethyl ammonium bromide (DDTAB) and tetradecyltrimethyl ammonium bromide (TDTAB) were carried out spectrophotometrically at λ_max = 289 nm. The values of the pseudo first order rate constant were found to be linearly dependent upon the [NaNO₂] in the concentration range of 1.0 × 10⁻³ mol dm⁻³ to 12.0 × 10⁻³ mol dm⁻³ in the presence of 2.0 × 10⁻² mol dm⁻³ acetic acid. The concentration of procaine was kept constant at 6.50 × 10⁻⁵ mol dm⁻³. The addition of the cationic surfactants increased the reaction rate and gave plateau like curve. The addition of SDS micelles to the reactants initially increased the rate of reaction and gave maximum like curve. The maximum value of the rate constant was found to be 9.44 × 10⁻³ s⁻¹ at 2.00 × 10⁻³ mol dm⁻³ SDS concentration. The azo coupling of diazonium ion with β-naphthol (at λ_max = 488) nm was found to linearly dependent upon [ProcN₂⁺] in the presence of both the cationic micelles (CTAB, DDTAB and TDTAB) and anionic micelles (SDS). Both the cationic and anionic micelles inhibited the rate of reactions. The kinetic results in the presence of micelles are explained using the Berezin pseudophase model. This model was also used to determine the kinetic parameters e.g. k_m, K_s from the observed results of the variation of rate constant at different [surfactants].     

Novel amphiphilic triblock copolymer based on PPDO,PCL, and PEG: Synthesis,characterization, and aqueous dispersion

Amphiphilic triblock copolymer, poly(p-dioxanone-co-caprolactone)-block-poly(ethylene oxide)-block-poly(p-dioxanone-co-caprolactone) (PPDO-co-PCL-b-PEO-b-PPDO-co-PCL) was synthesized by ring opening polymerization (ROP) of p-dioxanone and ɛ-caprolactone initiated through the hydroxyl end of poly(ethylene glycol) (PEG) in the presence of stannous 2-ethyl hexanoate [Sn(oct)₂] as a catalyst. Polymerization and structural features of the polymers were analyzed by different physicochemical techniques (GPC, ¹H NMR, ¹³C NMR, FT-IR, DSC and TGA). The splitting of ¹H NMR resonance at δ 2.3 and δ 4.1 ppm reveals the random copolymerization. Polymeric nanoparticles were prepared in phosphate buffer (pH 7.4) by co-solvent evaporation technique at room temperature (25 °C). Existence of hydrophobic domains as cores of the micelles were characterized by ¹H NMR spectroscopy and further confirmed with fluorescence technique using pyrene as a probe. Critical micelle concentration (CMC) of the polymer in phosphate buffer (pH. 7.4) was decreased from 2.3 × 10⁻³ to 7.6 × 10⁻⁴ g/L with the fraction of PCL. Polymeric nanoparticles observed by atomic force microscopy (AFM) were uniform and spherical, with smooth textured of around 50–30 nm diameter. Dynamic light scattering (DLS) and electrophoretic light scattering (ELS) measurements showed a monodisperse size distribution of around 113–90 nm hydrodynamic diameters and negative zeta (ζ) potential (−4 to −14 mV), respectively. The investigations for the polymeric nanoparticles in aqueous medium showed that the composition of the hydrophobic segment of amphiphilic block copolymer makes a significant influence on its physicochemical characteristics.     

TEMPO addition into pre-irradiated fluoropolymers and living-radical graft polymerization of styrene for preparation of polymer electrolyte membranes

We prepared proton exchange membranes (PEMs) by 2,2,6,6-tetramethylpiperidinyl-1-oxy (TEMPO)-mediated living-radical graft polymerization (LRGP) of styrene into fluoropolymer films and subsequent sulfonation. Poly(vinylidene fluoride) (PVDF) and poly(ethylene-co-tetrafluoroethylene) (ETFE) films were first irradiated and then treated with TEMPO solutions in various solvents. TEMPO addition was confirmed by the test of styrene grafting into TEMPO-treated films at 60 °C, at which the LRGP never proceeds. This test enabled us to differentiate the LRGP from the conventional graft polymerization. In order to gain a deep insight about TEMPO-addition reaction, the TEMPO-penetration behavior into the base polymer films was examined by a permeation experiment and computer simulation. Xylene and dioxane were appropriate solvents for the complete introduction of TEMPO into PVDF and ETFE films, respectively. Then, the LRGP of styrene was performed based on the fully TEMPO-capped films at 125 °C with various solvents. By using an alcoholic solvent, the degree of grafting was enhanced and it reached a maximum of 38%. This grafted film was sulfonated to prepare a PEM showing an ion exchange capacity of 2.2 meq/g and proton conductivity of 1.6×10^?1 S/cm.     

Fabrication of polymeric micelles with core–shell–corona structure for applications in controlled drug release

Thermo-responsive polymeric micelles of poly (ethylene glycol)-b-poly(2-hydroxyethyl methacrylate-g-lactide)-b-poly(N-isopropylacrylamide) (PEG-P(HEMA-PLA)-PNIPAM) with core–shell–corona structure were fabricated for applications in controlled drug release. The graft copolymer of PEG-P(HEMA-PLA)-PNIPAM was self-assembled into core–shell micelles with a densely PLA core and mixed PEG/PNIPAM shells at 25 °C in aqueous media. By increasing the temperature above the lower critical solution temperature of PNIPAM, these core–shell micelles could be converted into core–shell–corona micelles because of the collapse of PNIPAM block on the PLA core as the inner shell and the soluble PEG block stretching outside as the outer corona. Anticancer drug doxorubicin (DOX) was loaded in the polymeric micelles as a model drug. Compared with polymeric micelles formed by liner PEG-b-PLA-b-PNIPAM triblock copolymer, these polymeric micelles exhibited higher loading capacity, and release of DOX from the polymeric micelles with core–shell–corona structure was well-controlled.     

Synthesis and laser application of the dithiolene nickel complex compounds

A series of dithiolene nickel complex compounds with a general formula (RCSCSR′)₂Ni that have an intense absorption band in near-IR region were successfully synthesized and the maximum IR absorption wavelengths of these dyes vary from 875 to 1495 nm in different solvents. Their characteristics of Q-switching and mode-locking for different lasers were investigated. Q-switched 1064 and 1079 nm laser with a polymer film or organic solution work satisfactorily and the pulse widths are 4–10 ns. The dyes in a variety of solutions show excellent properties in mode-locking the 1079 nm laser, particularly in mode-locking the 1340 nm laser. The pulse widths are 90–120 ps. The experimental results show that the choice of different ring substitutes and solvents will greatly influence the corresponding dye laser properties. It is also implied that BDN16 and BDN17 as the mode-locking dyes for the 1500 nm laser are satisfactory.     

Design of a bioelectrocatalytic electrode interface for oxygen reduction in biofuel cells based on a specifically adapted Os-complex containing redox polymer with entrapped Trametes hirsuta laccase

The design of the coordination shell of an Os-complex and its integration within an electrodeposition polymer enables fast electron transfer between an electrode and a polymer entrapped high-potential laccase from the basidiomycete Trametes hirsuta. The redox potential of the Os^3+/2+-centre tethered to the polymer backbone (+ 720 mV vs. NHE) is perfectly matching the potential of the enzyme (+ 780 mV vs. NHE at pH 6.5). The laccase and the Os-complex modified anodic electrodeposition polymer were simultaneously precipitated on the surface of a glassy carbon electrode by means of a pH-shift to 2.5. The modified electrode was investigated with respect to biocatalytic O₂ reduction to H₂O. The proposed modified electrode has potential applications as biofuel cell cathode.     

The Ti@MoOx nanorod array as a three dimensional film electrode for micro-supercapacitors

Ti@MoO_x core–shell nanorod arrays with diameters within 100 nm were fabricated by electrodepositing MoO_x on a Ti nanorod array prepared by oblique angle deposition. A high areal capacitance of 27 mF cm^− 2 and satisfactory cycling stability were obtained. After post-annealing, MoO₂ grains were introduced to enhance the rate capability, suggesting a potential pseudocapacitive micro-electrode.     

Temperature-responsive photoluminescence of quinoline-labeled poly(N-isopropylacrylamide) in aqueous solution

The pH- and temperature-responsive optical properties of a quinoline-labeled poly(N-isopropylacrylamide) copolymer are explored in aqueous solution and compared to the respective behavior of a similar quinoline-labeled poly(N,N-dimethylacrylamide) copolymer. These copolymers, P(NIPAM-co-SDPQ) and P(DMAM-co-SDPQ), were prepared through free radical copolymerization of 2,4-diphenyl-6-(4-vinylphenyl)quinoline (SDPQ) with the thermosensitive N-isopropylacrylamide (NIPAM) and the hydrophilic N,N-dimethylacrylamide (DMAM), respectively. Both copolymers exhibit the well-known pH-controlled optical response of quinoline unit in aqueous solution and the emitted color changes from blue to green upon decreasing pH. Nevertheless, a ～20 nm emission shift is observed upon heating the aqueous P(NIPAM-co-SDPQ) solution, regardless of pH, due to the formation of hydrophobic microdomains (Nile Red probing), as a consequence of the Lower Critical Solution Temperature (LCST) behavior of this copolymer in water. Interestingly, this LCST behavior also imposes the partial deprotonation of the otherwise protonated SDPQ unit at pH = 2 and the emission of the basic form appears upon increasing temperature, suggesting that the acid/base equilibrium of the quinoline unit is significantly temperature-controlled, when introduced in the thermosensitive poly(N-isopropylacrylamide) chain.     

Novel core–shell SDC/amorphous Na2CO3 nanocomposite electrolyte for low-temperature SOFCs

Novel core–shell SDC (Ce_0.8Sm_0.2O_1.9)/amorphous Na₂CO₃ nanocomposite was prepared for the first time. The core–shell nanocomposite particles are smaller than 100 nm with amorphous Na₂CO₃ shell of 4–6 nm in thickness. The nanocomposite electrolyte shows superionic conductivity above 300 °C, where the conductivity reaches over 0.1 S cm⁻¹. Such high conductive nanocomposite has been applied in low-temperature solid oxide fuel cells (LTSOFCs) with an excellent performance of 0.8 W cm⁻² at 550 °C. A new potential approach of designing and developing superionic conductors for LTSOFCs was presented to develop interface as ‘superionic highway’ in two-phase materials based on coated SDC.     

Influence of chromophore dipole moments in parameterts of organic light emitting devices based on phenyl and methyl modified pyrazoloquinoline

Absorption, photo- and electroluminescence spectra of some trityl substituted 1H-pyrazolo[3,4-b]quinolines derivatives (methyl- and phenyl substituted) and fabrication of the single layered organic light emitting diodes are reported. The bulky trityl substituent was introduced to prevent aggregation and crystallization of the dopant in polymer matrix. Role of ground state dipole moments in the observed red Stokes shift, electroluminescent features and photocarrier transport is explored. The maximally achieved brightness about 50 Cd/m² is observed in the spectral range extending from 443 nm up to 462 nm. The voltage threshold was varied from 7.8 V up to 10 V. The brightness-current dependences show an existence of at least two types of carrier injections.     

A capillary water retention effect to improve medium-temperature fuel cell performance

We demonstrate that small and narrow hydrophilic conducting domain morphology in sulfonated aromatic membranes leads to much better fuel cell performance at medium temperature and low humidity conditions than those with larger hydrophilic domains. A comparison of three types of sulfonated poly(arylene ether sulfone)s (SPAES) with random, block, and graft architecture indicates that small hydrophilic domain sizes (< 5 nm) appear to be important in supporting water retention under low relative humidity (RH) conditions intended for medium temperature (> 100 °C) fuel cell applications. The graft copolymer outperformed both a random copolymer and multiblock copolymer at 120 °C and 35% RH fuel cell operating conditions due to capillary condensation of water within the 3–5 nm hydrophilic domains.     

Trace gas detection of benzene,toluene, p-, m- and o-xylene with a compact measurement system using cantilever enhanced photoacoustic spectroscopy and optical parametric oscillator

A compact measurement system based on a novel combination of cantilever enhanced photoacoustic spectroscopy (CEPAS) and optical parametric oscillator (OPO) was applied to the gas phase measurement of benzene, toluene, and o-, m- and p-xylene (BTX) traces. The OPO had a band width (FWHM) of 1.3 nm, was tuned from 3237 to 3296 nm in steps of 0.1 nm and so spectra of BTX at different concentrations were recorded. The power emitted by the OPO increased from 88 mW at 3237 nm to 103 mW at 3296 nm. The univariate detection limits (3σ, 0.951 s) for benzene, toluene, p-, m- and o-xylene at 3288 nm were 12.0, 9.8, 13.2, 10.1 and 16.0 ppb, respectively. Multivariate data analysis using science-based calibration was used to resolve the interference of the analytes. The multivariate detection limits (3σ, 3237–3296 nm, 591 spectral points each 0.951 s) for benzene, toluene, p-, m- and o-xylene in the multi-compound sample, where all other analytes and water interfere were 4.3, 7.4, 11.0, 12.5 and 6.2 ppb, respectively. Without interferents, the multivariate detection limits varied between 0.5 and 0.6 ppb. The sum of the cross-selectivities (3237–3296 nm, 591 spectral points, each 0.951 s) per analyte were below 0.05 ppb/ppb, with an average of 0.038 ppb/ppb. The cross-selectivity of water to the analytes was on average 1.22 × 10⁻⁴ ppb/ppb. The OPO is small in size (L × W × H 125 × 70 × 45 mm), commercially available, and easy to operate and integrate to setups. The combination with sensitive CEPAS enables compact measurement systems for industrial as well as environmental trace gas monitoring.     

Synthesis and electropolymerization of 1,2-bis(thiophen-3-ylmethoxy)benzene and its electrochromic properties and electrochromic device application

A new thiophene-based monomer; 1,2-bis(thiophen-3-ylmethoxy)benzene (BTMB) has been synthesized and chemical structure of the monomer was characterized. Polymerization of BTMB and characterization of the resulting polymer P(BTMB) were performed. Spectroelectrochemical analysis of the P(BTMB) reflected electronic transitions at 400 nm, 520 nm and ～720 nm, corresponding to π–π* transition, polaron and bipolaron band formation respectively. Switching ability was evaluated by a kinetic study via measuring the transmittance (%T) at the maximum contrast. Dual type all polymer electrochromic device (ECD) based on P(BTMB) and poly(ethylene dioxythiophene) (PEDOT) was constructed. Spectroelectrochemistry and switching ability of the devices were investigated by UV–vis spectroscopy.     

Robust polyazobenzene microcapsules with photoresponsive pore channels and tunable release profiles

Monodisperse silica particles coated with azobenzene polymer (PAzo) shell were synthesized through distillation precipitation polymerization. Robust PAzo microcapsules were obtained after selective removal of the silica templates by hydrofluoric acid (HF) etching. These PAzo microcapsules, confirmed by transmission electron microscopy (TEM) investigation, had excellent reversible photoisomerization with transformation between trans and cis isomers under ultraviolet (UV) and visible lights. Due to their compatibility with PAzo, acetonitrile would be trapped in the network of the shell during polymerization. Pore channels in the shell, confirmed by nitrogen adsorption–desorption test, would be produced after acetonitrile evaporation. Loading and release of rhodamine B (RhB) molecules in PAzo microcapsules were carried out and indicated that cis azobenzene showed larger pore diameter (named as “open switch”) under UV light which favored permeation of RhB molecules, while trans structure (named as “closed switch”) under visible light slowed down the process. In addition, both release profiles obeyed pure Fickian diffusion with a power law of t^0.42. Diffusion coefficient of RhB from PAzo microcapsules under visible light (1.47 × 10^?12 cm²/s) was lower than that under UV light (2.12 × 10^?12 cm²/s).     

Multidimensional system enabling deglycosylation of proteins using a capillary reactor with peptide-N-glycosidase F immobilized on a porous polymer monolith and hydrophilic interaction liquid chromatography–mass spectrometry of glycans

A reactor with immobilized peptide-N-glycosidase F on a monolithic polymer support in a capillary has been developed that allows fast and efficient release of N-linked glycans from immunoglobulin G molecules. Two different monolithic scaffolds based on poly(glycidyl methacrylate-co-ethylene dimethacrylate) and poly(butyl methacrylate-co-ethylene dimethacrylate) were prepared. A multistep photografting process was used to reduce non-specific adsorption of proteins and to obtain support containing reactive azlactone functionalities enabling the preparation of highly active immobilized peptide-N-glycosidase F. Performance of these reactors was determined through glycan release from several glycoproteins including ribonuclease B, chicken albumin, and human immunoglobulin G and their detection by matrix-assisted laser desorption-ionization/time-of-flight mass spectrometry. The optimized reactor was integrated into a multidimensional system comprising on-line glycan release and their separation via hydrophilic interaction liquid chromatography followed by electrospray ionization/time-of-flight mass spectrometry detection. Using the optimized monolithic reactor with immobilized peptide-N-glycosidase F, human immunoglobulin G was deglycosylated at room temperature in 5.5 min to an extent similar to that achieved with soluble enzyme after 24 h at 37 °C.     

Ordered nanopore boring in silicon: Metal-assisted etching using a self-aligned block copolymer Au nanoparticle template and gravity accelerated etching

Metal-assisted etching into Si (1 0 0) surfaces can be performed in a highly defined and regular arrangement using self-organized patterns of single-size gold catalyst particles that are block polymer templated on Si surfaces. We show that small size catalyst particles (diameter ≈10 nm) can be forced to maintain straight etch tracks perpendicular to the surface using adequate centrifugal gravity force. This allows the creation of highly ordered uniform and synchronized pore boring into the substrate with single pore diameters in the 10 nm range.     

Vapour pressure osmometry determination of water activity of binary and ternary aqueous (polymer + polymer) solutions

Precise water activity measurements at T = 308.15 K were carried out on several binary (water + polymer) and ternary {water + polymer (1) + polymer (2)} systems using the vapour pressure osmometry (VPO) technique. Polymers were polyethylene glycol 400 (PEG400), polyethylene glycol 6000 (PEG6000), polypropylene glycol 400 (PPG400), polyvinylpyrrolidone (PVP) and dextran (DEX). The water activity results obtained were used to calculate the vapour pressure of solutions as a function of concentration and the segment-based local composition models, NRTL and Wilson, were used to correlate the experimental water activity values. It was found that, for the polymer concentration range studied here, the values of the water activity obtained for the binary (water + polymer) solutions decrease in the order DEX > PVP > PEG6000 > PPG400 > PEG400. Furthermore, water activities of solutions of each polymer in the aqueous solutions of (5, 10, 15 and 20)% (w/w) other polymers investigated were also measured at T = 308.15 K. The ability of polymer (1) in decreasing the water activity of binary {water + polymer (2)} solutions was discussed on the basis of the (polymer + water) and {polymer (1) + polymer (2)} interactions.     

Intercalation of melamine into layered zirconium phosphates and their adsorption properties of formaldehyde in gas and solution phase

The intercalations of melamine into α- and γ-zirconium phosphates (α- and γ-ZrP) were investigated. Melamine-intercalated α-ZrP afforded two phases with different interlayer distances (d = 1.30 and 1.55 nm). The phase with d = 1.30 nm was obtained as the mixture with original α-ZrP at 30 min reaction by batch method, whereas the single phase with d = 1.55 nm was obtained by decantation method in saturated melamine aqueous solution. Contrary to this, for γ-ZrP a phase with d = 1.78 nm was obtained by both batch and decantation methods in saturated melamine aqueous solution. And new phase with d = 1.48 nm was formed in batch method at low pH or lower concentration of melamine aqueous solution. In these phases the arrangement of melamine changed from a monolayer structure to a bilayer structure with the increase of interlayer distance. Furthermore, melamine-intercalated α- and γ-ZrP adsorbed formaldehyde gas and formaldehyde in formalin solution by interacting with melamine molecule in the interlayer region. In melamine-intercalated γ-ZrP with d = 1.48 nm, the expansion of interlayer distance to around 1.6 nm was observed after the adsorption of formaldehyde gas and formaldehyde in formalin solution. The adsorption of formaldehyde in formalin solution was accompanied with the release of melamine in the interlayer region with increasing the concentration of formaldehyde at 65 °C.     

Solid state electrochromic device applications of N-(2-(thiophen-3-yl)methylcarbonyloxyethyl) maleimide

Homopolymer and copolymer of N-(2-(thiophen-3-yl)methylcarbonyloxyethyl) maleimide (NMThi) with thiophene [P(NMThi-co-Th)] were synthesized electrochemically in acetonitrile/borontrifluoride ethylether solvent mixture (1:1, v/v). Spectroelectrochemical analysis of the resulting copolymer reflected electronic transitions at 488 and 718 nm revealing π to π¹ transition and polaron formation, respectively. Switching ability was evaluated by a kinetic study via measuring the transmittance (%T) at the maximum contrast. Dual-type polymer electrochromic devices (ECDs) based on homopolymer (P(NMThi) and copolymer P(NMThi-co-Th) were constructed with poly(3,4-ethylenedioxythiophene) (PEDOT). Spectroelectrochemistry and switching ability of the devices were investigated by UV–vis spectroscopy and cyclic voltammetry.