Ion conduction and phase morphology in sulfonate copolymer ionomers based on ionic liquid–sodium cation mixtures

A series of sulfonate based copolymer ionomers based on a combination of ionic liquid and sodium cations have been prepared in different ratios. This system was designed to improve the ionic conductivity of ionomers by partially replacing sodium cations with bulky cations that are less associated with anion centres on the polymer backbone. This provides more conduction sites for sodium to ‘hop’ to in the ionomers. Characterization showed the glass transition and 15N chemical shift of the ionomers did not vary significantly as the amount of Na+ varied, while the ionic conductivity increased with decreasing Na+ content, indicating conductivity is increasingly decoupled from Tg. Optical microscope images showed phase separation in all compositions, which indicated the samples were inhomogeneous. The introduction of low molecular weight plasticizer (PEG) reduced the Tg and increased the ionic conductivity significantly. The inclusion of PEG also led to a more homogeneous material.

Decoupled ion conduction in poly(2-acrylamido-2-methyl-1-propane-sulfonic acid) homopolymers

As the focus on developing new polymer electrolytes continues to intensify in the area of alternative energy conversion and storage devices, the rational design of polyelectrolytes with high single ion transport rates has emerged as a primary strategy for enhancing device performance. Previously, we reported a series of sulfonate based copolymer ionomers based on using mixed bulky quaternary ammonium cations and sodium cations as the ionomer counterions. This led to improvements in the ionic conductivity and an apparent decoupling from the Tg of the ionomer. In this article, we have prepared a new series of ionomers based on the homopolymer of poly(2-acrylamido-2-methyl-1-propane-sulfonic acid) using differing sizes of the ammonium counter-cations. We observe a decreasing Tg with increasing the bulkiness of the quaternary ammonium cation, and an increasing degree of decoupling from Tg within these systems. Somewhat surprisingly, phase separation is observed in this homopolymer system, as evidenced from multiple impedance arcs, Raman mapping and SEM. The thermal properties, morphology and the effect of plasticizer on the transport properties in these ionomers are also presented. The addition of 10 wt% plasticizer increased the ionic conductivity between two and three orders of magnitudes leading to materials that may have applications in sodium based devices. This journal is

The surface finish of thermally aged carbon fibre reinforced composites using E-glass as a surface barrier

This work investigated the effect of woven E-glass mass (25 g/m2, 50 g/m2, 85 g/m2, 135 g/m2) on the painted surface finish of various thermoset (EPIKOTETM RIM935, EPIKOTETM 04434, Ultratec LpTM ES300, Ultratec LpTM SPV6035) carbon fibre composite laminates, before and after aging at 95 °C for 168 h. The as-moulded laminate surfaces were evaluated using surface profilometry techniques and the painted and aged surfaces were evaluated using a wave-scan distinctness of image (DOI) instrument. It was found that the 25 g/m2 E-glass surface layer assisted with reducing the roughness of the as-moulded surfaces and the long-term waviness of the painted surfaces due to the increase in resin-richness at the surface. The EPIKOTETM 04434 resin system that contained diglycidyl ether of bisphenol F (DGEBF) epoxy had the least change in long-term waviness with thermal aging due to the rigid fluorene-based backbone in comparison to the diglycidyl ether of bisphenol A (DGEBA) systems.

Zwitterion effect in polyelectrolyte gels based on lithium methacrylate-N,N-dimethyl acrylamide copolymer

Zwitterionic compounds such as those based on 1-butylimidazolium-3-(n-butanesulfonate) have previously been shown to have positive effects on the transport properties of polyelectrolytes. The addition of the zwitterion has been found to, in some cases, increase the dissociation of the lithium ion and enhance the conductivity by almost an order of magnitude. In this work, we report the effects of adding the above-mentioned zwitterion into the polyelectrolyte gel system poly(lithium methacrylate-co-N,N-dimethyl acrylamide); the anionic group being a stronger base leads to different behaviour for this copolymer compared to previous work. Polyelectrolyte gels based on dimethyl sulfoxide and polyether solvents were investigated to determine the breadth of applicability of the zwitterion in improving lithium ion transport. Impedance spectroscopy and pulse field gradient-NMR diffusion indicate an increase in the number of available charge carriers with zwitterion addition in some gel systems, however, the effect is not universal.

Polyoxometalate-based hybrid organogels prepared from a triblock copolymer via charge-driven assembly

We report a novel approach for the preparation of polyoxometalate-based hybrid organogels from a triblock copolymer via charge-induced assembly. The triblock copolymer used is poly(4-vinyl pyridine)-block-poly(ethylene glycol)-block-poly(4-vinyl pyridine) (4VPm-EGn-4VP m), and polyoxometalate (POM) is phosphotungstic acid (HPW). The ionic interaction between the pyridine groups of the 4VPm-EG n-4VPm and HPW drives the assembly of the triblock copolymer to form solvophobic cores. The PEG middle blocks connect and stabilize the different cores to form hybrid organogels. The structures of POM remain unchanged in these hybrid organogels, and the properties of POMs can be preserved, which has been confirmed by the existence of photo-reduction properties of POM in the hybrid organogels. © 2014 the Partner Organisations.

An anti-biodegradable hydrophobic sulfonate-based acrylamide copolymer containing 2,4-dichlorophenoxy for enhanced oil recovery

We report here a novel anti-biodegradable hydrophobic acrylamide copolymer that was prepared from acrylamide, acrylic acid, sodium 3-(allyloxy)-2-hydroxypropane-1-sulfonate and N-allyl-2-(2,4-dichlorophenoxy) acetamide using the 2,2'-azobis(2-methylpropionamide) dihydrochloride initiation system. Subsequently, the copolymer was characterized by FT-IR, 1H NMR, TG-DTG and water-solubility. And the biodegradability test indicated that the copolymer was not deemed to be readily biodegradable via a closed bottle test established by the Organization for Economic Co-operation and Development (OECD 301 D). Meanwhile the copolymer could significantly enhance the viscosity of the aqueous solution in comparison with partially hydrolyzed polyacrylamide. A viscosity retention of 51.9% indicated the result of a dramatic improvement of temperature tolerance. And then the excellent salt resistance, shear resistance, viscoelasticity, long-term stability of the copolymer could be obtained, which provides a good theoretical foundation for the application in enhanced oil recovery. In addition, this copolymer exerted stronger mobility control ability with a resistance factor of 22.1 and a residual resistance factor of 5.0, and superior ability for enhanced oil recovery of 12.9%. Hence, the copolymer has potential application for enhanced oil recovery in high-temperature and high-salinity reservoirs.

A novel α-aminophosphonic acid-modified acrylamide-based hydrophobic associating copolymer with superb water solubility for enhanced oil recovery

As a non-renewable resource, the rational exploitation of oil has attracted a large amount of attention. Among many methods for enhanced oil recovery, polymer flooding is the most suitable method of chemical flooding for non-marine reservoirs and therefore various modified acrylamide-based copolymers have been studied. In this study, a novel α-aminophosphonic acid-modified hydrophobic associating copolymer was successfully synthesized by copolymerization of acrylamide, acrylic acid, N-allyldodecanamide and 1-(dimethylamino)allylphosphonic acid. The copolymer was characterized by FT-IR, 1H NMR and thermogravimetry and exhibited superior water solubility and thickening capability. Subsequently, the shear resistance, temperature resistance and salt tolerance of the copolymer solution were investigated. The value of apparent viscosity retention of a 2000 mg L-1 copolymer solution was as high as 58.55 mPa s at a shear rate of 170 s-1 and remained at 40.20 mPa s at 120 °C. The values of apparent viscosity retention of 55.41 mPa s, 59.95 mPa s and 52.97 mPa s were observed in solutions of 10000 mg L-1 NaCl, 1200 mg L-1 MgCl2, and 1200 mg L-1 CaCl2, respectively. These were better than those of partially hydrolyzed polyacrylamide under the same conditions. In addition, an increase of up to 14.52% in the oil recovery rate compared with that for water flooding could be achieved in a core flooding test using a 2000 mg L-1 copolymer solution at 65 °C.

Nanostructures and nanoporosity in thermoset epoxy blends with an amphiphilic polyisoprene-block-poly(4-vinyl pyridine) reactive diblock copolymer

Nanostructured thermoset blends were prepared based on a bisphenol A-type epoxy resin and an amphiphilic reactive diblock copolymer, namely polyisoprene-block-poly(4-vinyl pyridine) (PI-P4VP). Infrared spectra revealed that the P4VP block of the diblock copolymer reacted with the epoxy monomer. However, the non-reactive hydrophobic PI block of the diblock copolymer formed a separate microphase on the nanoscale. Ozone treatment was used to create nanoporosity in nanostructured epoxy/PI-P4VP blends via selective removal of the PI microphase and lead to nanoporous epoxy thermosets; disordered nanopores with the average diameter of about 60 nm were uniformly distributed in the blend with 50 wt% PI-P4VP. Multi-scale phase separation with a distinctly different morphology was observed at the air/sample interface due to the interfacial effects, whereas only uniform microphase separated morphology at the nanoscale was found in the bulk of the blend.

Ion and solvent dynamics in gel electrolytes based on ethylene oxide grafted acrylate polymers

Multinuclear pulsed field gradient NMR measurements and rheological viscosity measurements were performed on three series of polymer gel electrolytes. The gels were based on a lithium salt electrolyte swollen into a copolymer matrix comprising an acrylate backbone and ethylene oxide side chains. In each series the side chains differed in length and number, but the acrylate-to-ethylene oxide ratio was kept constant. It was found that the self-diffusion coefficient of the cations was much lower than that of the anions, and that it decreased rapidly when the side chains got longer. In contrast, the self-diffusion coefficient of the anions was found to be independent of chain length. In the gel electrolytes, the diffusion coefficients of the solvent molecules are relatively constant despite an increased viscosity with increasing length of the side chains. However, in salt-free gels made for comparison, the diffusion coefficients of the solvent molecules decreased with increasing length of the side chains, which is consistent with an increased viscosity.

Microphase separation through competitive hydrogen bonding in double crystalline diblock copolymer/homopolymer blends

Microphase separation induced by competitive hydrogen bonding interactions in double crystalline diblock copolymer/homopolymer blends was studied for the first time. Poly(ethylene oxide)- block-poly(e-caprolactone) (PEO-b-PCL)/poly(4-vinylphenol) (PVPh) blends were prepared in tetrahydrofuran. The diblock copolymer PEO-b-PCL consists of two immiscible crystallizable blocks wherein bothPEO and PCL blocks can form hydrogen bonds with PVPh. In these A-b-B/C diblock copolymer homopolymer blends, microphase separation takes place due to the disparity in intermolecular interactions; specifically, PVPh and PEO block interact strongly whereas PVPh and PCL block interact weakly. The TEM and SAXS results show that the cubic PEO-b-PCL diblock copolymer changes into ordered hexagonal cylindrical morphology upon addition of 20 wt % PVPh followed by disordered bicontinuous phase in the blend with 40 wt % PVPh and then to homogeneous phase at 60 wt % PVPh and above blends. Up to 40 wt % PVPh there is only weak interaction between PVPh and PCL due to the selective hydrogen bonding between PVPh and PEO. However, with higher PVPh concentration, the blends become homogeneous since a sufficient amount of PVPh is available to form hydrogen bonds with both PEO and PCL. A structural model was proposed to explain the self-assembly and microphase morphology of these blends based on the experimental results obtained. The formation of nanostructures and changes in morphologies depend on the relative strength of hydrogen bonding interaction between each block of the block copolymer and the homopolymer.

Novel biorenewable plastics based on natural resources using ionic liquids

We report biorenewable plastics developed from natural resources such as cellulose, wool and microorganismsynthesized poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) copolymer [1-3]. Novel materials were prepared by blending these natural polymers in an ionic liquid green solvent, 1-butyl-3-methylimidazolium chloride. Cellulose /PHBV blend materials were successfully prepared in this way. The ionic liquid was completely recycled with high yield and purity after the processing. The blend materials can be processed into different solid forms such as films, noodle-like fibers and bulk blocks. It was found that there exists hydrogen bonding interaction between the components which facilities the mixing of these polymers. The cellulose/PHBV blend materials all show phase-separated structure as revealed by micro ATR-FTIR imaging (Figure 1) and scanning electron microscopy (SEM). The PHBV domains of 6 - 8 µm are distributed in a cellulose matrix at high concentrations of cellulose while the blend materials with high PHBV concentrations exhibit multiphase morphologies, including beadlike PHBV microdomains in the range of 300-400 nm. The dispersion of PHBV in cellulose leads to significant improvement in hydrophobicity due to its beadlike structure. The blend materials represent a class of degradable plastics from natural bioresources using the ionic liquid green solvent.

Self-assembly and competitive hydrogen bonding interactions of double crystalline diblock copolymer/homopolymer blends

In the present work, nanostructured blends were prepared from double crystalline diblock copolymer poly(ɛ-caprolactone)-block-poly(ethylene oxide) and homopolymer poly(4-vinyl phenol) (PVPh). The diblock copolymer PEO-b-PCL consists of two immiscible crystallizable blocks wherein both PEO and PCL blocks can form hydrogen bonds with PVPh. In these A-b-B/C diblock copolymer/homopolymer blends, microphase separation takes place due to the disparity in intermolecular interactions; specifically, PVPh and PEO block interact strongly whereas PVPh and PCL block interact weakly. The TEM and SAXS results show that the cubic PEO-b-PCL diblock copolymer changes into ordered hexagonal cylindrical morphology upon addition of 20 wt % PVPh followed by disordered bicontinuous phase in the blend with 40 wt % PVPh and then to homogeneous phase at 60 wt % PVPh and above blends. Up to 40 wt % PVPh there is only weak interaction between PVPh and PCL due to the selective hydrogen bonding between PVPh and PEO. However, with higher PVPh concentration, the blends become homogeneous since a sufficient amount of PVPh is available to form hydrogen bonds with both PEO and PCL. A structural model was proposed to explain the self-assembly and microphase morphology of these blends based on the experimental results obtained. The formation of nanostructures and changes in morphologies depend on the relative strength of hydrogen bonding interaction between each block of the block copolymer and the homopolymer.

Self-assembly and morphology in double crystalline diblock copolymer/homopolymer blends with competitive hydrogen bonding

Block copolymers are of particular interest due to their ability to form a rich variety of nanostructures via self-assembly [1]. The self-assembly via competitive hydrogen bonding is a novel concept which is based on the competition between different blocks of the block copolymer to form more than one kind of intermolecular interaction with the complimentary polymer in the system. Recently, Guo and co-workers have proven that careful selection of the polymers specifically the block copolymer, and the experimental conditions can lead to self-assembled structures in blends and complexes exhibiting competitive hydrogen bonding [2-5].

Microphase separation induced by competitive hydrogen bonding interactions in semicrystalline triblock copolymer/homopolymer complexes

Microphase separation through competitive hydrogen bonding interactions in ABC/D triblock copolymer/ homopolymer complexes is studied for the first time. This study investigated self-assembled nanostructures that are obtained in the bulk, by the complexation of a semicrystalline polystyrene-block-poly(4-vinylpyridine)-block-poly(ethylene oxide) (SVPEO) triblock copolymer with a poly(4-vinyl phenol) (PVPh) homopolymer in tetrahydrofuran (THF). In these complexes, microphase separation takes place due to the disparity in intermolecular interactions among PVPh/P4VP and PVPh/PEO pairs. At low PVPh concentrations, PEO interacts relatively weakly with PVPh, whereas in the complexes containing more than 30 wt% PVPh, the PEO block interacts considerably with PVPh, leading to the formation of composition-dependent nanostructures. SAXS and TEM results indicate that the cylindrical morphology of a neat SVPEO triblock copolymer changes into lamellae structures at 20 wt% of PVPh then to disordered lamellae with 40 wt% PVPh. Wormlike structures are obtained in the complex with 50 wt%PVPh, followed by disordered spherical microdomains with size in the order of 40–50 nm in the complexes with 60–80 wt% PVPh. Moreover, when the content of PVPh increases to 80 wt%, the complexes show a completely homogenous phase of PVPh/P4VP and PVPh/PEO with phase separated spherical PS domains. The fractional crystallization behavior in SVPEO and complexes at lower PVPh content was also examined. A structural model was proposed to explain the microphase separation and self-assembled morphologies of these complexes based on the experimental results obtained. The formation of nanostructures and changes in morphologies depend on the relative strength of hydrogen bonding interactions between each component block of the copolymer and the homopolymer.

Cellulose-based biodegradable blends and composites regenerated from ionic liquids

This thesis presents the fabrication of biodegradable polymer blends and composites with the assistance of ionic liquids. The work included preparation and characterization of cellulose/PCL blend films, cellulose/ PCL-PDMS-PCL blend films, cellulose/ PVAL blend films and cellulose/clay composite films. An efficient and feasible approach of reducing plastic pollution was developed.