To increase electrode cycling performance in batteries, most researchers generally focus their work on the active material optimisation. Here we show that the polymeric binder of the composite electrode may have an important role on the electrode performance. We describe a new tailored polymeric binder combination with controlled polymer-filler (carbon black) interactions that allows the preparation of new and more efficient electrode architecture. Using this polymeric binder, composite electrodes based on Li1.2V3O8 display a room-temperature cycling capacity of 280 mAh/g (C/5 rate, 3.3–2 V) instead of 150 mAh/g using a standard-type (PVdF-HFP binder) composite electrode. We have coupled SEM observations, galvanostatic cycling and electronic conductivity measurements in order to define and understand the impact of the microstructure of the composite electrode on its electrochemical performance.

We performed Brownian Dynamics simulations of multiblock copolymers of A and B polymers in a solvent selective for the A block at a volume fraction of 20%. Tri-, penta- and heptabocks were simulated. Fourier transformation reveals micellar clusters arranged in a BCC lattice, in agreement with scattering experiments. The clusters were analyzed using a percolation approach and we observed larger clusters when the outermost block was in the poor solvent condition. The ratio of number of loops to bridges decreases as the number of blocks in the copolymer increases, as does the polydispersity. Increased penalty of looping as the number of blocks increases leads to a larger number of smaller clusters with more bridges.

PVDF-based electroactive polymers (EAP) exhibit high electromechanical performance that is attractive for developing high performance actuators and sensors. In an effort to develop very inexpensive electroactive polymers, P(VDF-TrFE)/P(VDF-CTFE) copolymer blends are studied and reported. The structure, morphology, thermal transition and miscibility of the blend system were investigated by DSC and X-ray diffraction. It is found that the phase transition behavior of the blends can be significantly modified using thermal and mechanical treatmentss. The modified film exhibits high polarization response and low remanent polarization. More importantly, a high electrostrictive strain of 5% was observed in the treated blends. Combined with Young's modulus, the results show that the copolymer blends have a electromechanical coupling factor and energy density comparable or even higher than the irradiated P(VDF-TrFE) copolymers.

The main objective of this study is to determine the effects of short glass fiber (SGF) content and extrusion conditions such as screw speed and barrel temperature, on the mechanical properties and morphologies of structural composites produced by compounding SGFs with poly (acrylonitrile-butadiene-styrene) (ABS). It was also aimed to determine the effects of adhesion at the fiber/matrix interface, which was promoted by incorporation of polyamide-6 (PA6) to the ABS/SGF composite. Results showed that increasing screw speed during extrusion decreased the average fiber length; therefore mechanical properties of the composites affected negatively. The increasing extrusion temperature decreased the fiber length degradation and higher tensile strength and modulus values were obtained. The use of PA6 in composites increased the interfacial adhesion, which was supported by SEM microphotographs; therefore, improved mechanical properties were obtained.

Morphology development of crystallizable polymer blends has been investigated using optical microscopy, thermal analysis, and vibrational spectroscopy. The blends studied involve crystallizable polyesters of poly(hexamethylene adipate) (PHMA) and poly(hexamethylene sebacate) (PHMS) and non-crystallizable poly(propylene glycol) (PPG). Although these polyesters possess similar chemical structure, they exhibit different phase behavior. Ternary blends including a high glass transition temperature (T g ) component were also studied. Crystallization kinetics in these blends was obtained utilizing Fourier transform infrared spectroscopy. Micro-Raman spectroscopy capable of achieving high spatial resolution (1 μm2) revealed detailed morphological differences in the phase-separated structures. This technique made possible for the first time characterization of the chemical composition of the blends and distribution of crystallites. The role of the third relative immobile component significantly changed both chemical distribution and the degree of crystallinity.

The dynamic structure factor S(q, t) of ultra-high molecular mass diblock copolymers BC in a common solvent was systematically investigated by photon correlation spectroscopy in different regimes of the phase diagram. Through proper probing of the composition fluctuations in symmetric and asymmetric BC the different relaxation mechanisms were identified and the influence of the disorder to order (ODT) transition was assessed. In the disordered regime, S(q, t) sensitively depends on the composition polydispersity of BC and the proximity to ODT complementing the real phase morphology of BC. The dynamic response of BC is therefore predictable.

The addition of small molecule fluorosurfactants to perfluorosulfonate ionomers has been found to have a profound effect on the morphology and mechanical properties of solution processed membranes. Perfluorooctane sulfonates neutralized with both alkali metal and alkylammonium counterions have been incorporated into solution processed Nafion® membranes. Sodium neutralized fluorosurfactants were found to crystallize during membrane casting leading to the formation of a surface layer of crystalline material.

Tetramethylammonium neutralized surfactants behave in a similar fashion with crystallization of the surfactant occurring during casting. The use of large tetrabutylammonium counterions is found to prevent crystallization of the surfactant and create a highly plasticized membrane.

Using large scale particle dynamics simulations, we investigated the effect of nanoscale rods on the dynamics of phase separation dynamics of two-component fluids in three dimensions. We found that when the nanoparticles interact more attractively with one of the two segregating component, they lead to a reduction of the rate of domain growth, and that this decrease is intensified as the nanoparticles volume fraction is increased. Furthermore, our results show that nanorods are much more effective in slowing down the kinetics than nanosphres. The dramatic effect of nanorods on the dynamics of phase separation of multi-component fluids, as opposed to nanospheres, implies that they may be used as an efficacious emulsifying agent of multi-component polymer blends.

Nanoporous polymer films have been prepared using immiscible blends of polyetherimide (PEI) and poly(caprolactone diol) (PCLD). The films were prepared by spin-coating from a common solvent — dichloromethane (DCM). To create the nanoporous films, PCLD was removed by immersing the films in acetone, which dissolves PCLD only. Field emission scanning electron microscopy was used to study the porous structure. The pore structure of the films was affected by many factors such as composition of the blend, molecular weight, and various processing parameters. The formation of nanometer size pores was mainly due to the fast phase separation process during spin-coating. The pore size and pore size distribution was found to depend on the blend composition.

In this work, we found that by performing photo-polymerization of the mesogenic monomer RM257 in liquid crystals, well organized polymer walls were formed through out the cell by self-assembly of the polymer within the anisotropic host – the liquid crystal. The polymerization conditions, which were parameterized as UV intensity, photo-reactivity (characterized by photo initiator concentration), curing temperature, monomer concentration and mesophase of the liquid crystal host, were systematically varied. Different liquid crystal host also raised some difference in polymer network. We believe this kind of morphology comes from spinodal decomposition and the anisotropic elastic property of the liquid crystal host. It is found that for RM257 and low molecular weight nematic liquid crystals a monomer concentration of 5% is sufficient to use liquid crystal hosts to work as templates for well structured polymer walls.

Spectroscopic studies on a series of rod-coil block copolymers with terfluorene as the rigid segment demonstrate that the main cause of color instability in fluorene oligomers and polymers is aggregate and/or excimer formation and not the presence of keto defects alone (fluorenone formation) along the molecular chain. Keto defects when are present contribute to the appearance of the undesirable ‘green’ emission band but are not the leading cause of color instability. Thus, the synthesis of materials where aggregation and/or inter-chain, inter-segment interactions are inhibited is the key approach for the production of stable polymeric light-emitting devices (PLED's). The potential of this method is verified by the synthesis of photo-oxidative stable fluorene/styrene diblock copolymer blue emitters.

The conductivity and mechanical stiffness of ethylene-oxide based Li+ conducting solid polymer electrolytes (SPE) were measured and compared for a variety of single- and two-phase systems. Our objective was to determine whether there are simple correlations between these two properties despite the fact that these systems are truly complex. Results show that molecular architecture dominates both transport and mechanical behavior of single phase systems, thereby eliminating broad correlations. Conductivity was additionally found to require not only facile local chain dynamics but also a sufficient concentration of vacancies, as per the site hopping model. Two phase systems also show complex behaviors, but offer a broader range of both conductivity and stiffness values, and good conductivity/stiffness correlations.

Ti(III)Cp2Cl-catalyzed radical ring opening (RRO) of epoxides or single electron transfer (SET) reduction of aldehydes generates Ti alkoxides and carbon centered radicals which add to styrene, initiating a radical polymerization. This polymerization is mediate in a living fashion by the reversible termination of growing chains with the TiCp2Cl metalloradical. In addition, polymers or monomers containing pendant epoxide groups (glycidyl methacrylate) can be used as substrates for radical grafting or branching reactions by self condensing vinyl polymerization. In addition, Ti alkoxides generated in situ by both epoxide RRO and aldehyde SET initiate the living ring opening polymerization of ε-caprolactone. Thus, new initiators and catalysts are introduced for the synthesis of complex polymer architectures.

Molecular dynamics and Grand Canonical Monte Carlo simulations have been used to obtain the glass transition temperatures and the water uptake for polyimides synthesized from Naphthalene-1, 4, 5, 8-tetracaboxylic dianhydride (NTDA), 2, 2'-benzidinedisulfonic acid (BDSA), 4, 4'-diaminodiphenylether-2, 2'-disulfonic acid (ODADS), and non-sulfonated diamine monomers. The glass transition temperature T gs of these polyimide copolymers have been determined from plots of specific volumes versus temperatures above and below T gs. The simulation results suggest that the ODADS-based polyimide membranes have lower T gs and better mechanical properties than the BDSA-based polyimides, which can be attributed to high mobility of the backbones of ODADS as supported by the vectorial autocorrelation function (VACF) results of this study. In addition, comparisons of the simulated T gs for ODADS-based polyimides of various degrees of hydration show that water content in polyimides may enhance their mechanical properties by lowering the T gs. In the case of water uptake of these polyimide copolymers, the GCMC simulation results indicate better water solubility for more sulfonated polymers.

This paper describes mechanical properties of polymer-clay nanocomposites with platelet and fibrous like nanoparticles evaluated on a of nano, meso and micro length scale. Platelet reinforced materials were found to display a mixed morphology consisting of intercalated and exfoliated regions. A better dispersion was obtained for fibrous clay nanocomposites where homogeneous distribution of single particles was achieved. The deformation behavior was investigated by in-situ XRD and SEM experiments during drawing; the macro-mechanical characteristics were extracted from tensile tests. The stiffness was found to increase in both platelet and fibrous clay nanocomposites. The presence of intercalated stacks in the latter resulted in a significant reduction in drawability, the better homogeneity of the fibrous clay systems allowed a reasonably high extensions.

We model a novel process for obtaining controlled morphologies in polymer blends. Particles of one type of polymer are allowed to dissolve in a matrix of a dissimilar polymer. Prior to complete dissolution the blend is quenched into the two phase region, such that phase separation takes place. The combination of the incomplete dissolution and the wavelength selection process associated with phase separation results in particles that during the ‘intermediate’ stages have a core that is significantly rich in the matrix material. The concept is extended to consider the effect of phase separation on an inhomogeneous surface chemically patterned with regions which are more attractive to one component of the blend.

Complex phase transformation between the hexagonal cylinder (Hex) and double gyroid (G) phases in a polystyrene-block-poly(ethylene oxide) (PS-b-PEO) diblock copolymer was investigated using two-dimensional (2D) synchrotron small-angle X-ray scattering (SAXS), and transmission electron microscope (TEM). The PS-b-PEO sample contained a small population of another bicontinuous cubic phase having an Im 3 m symmetry. These two bicontinuous cubic phases (G and Im 3 m) had the same unit cell dimensions. Under a large-amplitude reciprocating shear, the bicontinuous cubic phases transformed into a “single-crystal”-like Hex phase. When annealed at 150 °C for 40 min, the Hex phase partially transformed into well-oriented twinned structures of the G and Im 3 m phases without significant loss of orientation in 2D SAXS measurements. Epitaxial phase transformation relationships between the Hex/G and Hex/ Im 3 m phases were identified. The mechanism of the Hex → G transformation was examined by TEM.

This study was conducted to investigate the effects of component concentrations and addition order of the components, on the final properties of ternary nanocomposites composed of poly(ethylene terephthalate), organoclay, and an ethylene/methyl acrylate/glycidyl methacrylate (E-MA-GMA) terpolymer acting as an impact modifier for PET. Among the investigated addition orders, the best sequence of component addition (PI-C i.e. PET, Impact Modifier-Clay) was the one in which poly (ethylene terephthalate) was first compounded with E-MA-GMA. Later, this mixture was compounded with the organoclay in the subsequent run. In X-ray diffraction analysis, extensive layer separation associated with delamination of the original clay structure was observed in PI-C and (CI-P i.e. Clay, Impact Modifier-PET) sequences with both 1 and 3 wt. % clay contents. X-ray diffraction patterns showed that, at these conditions, exfoliated structures were obtained.

This paper describes the effects of structures on the glass transition of glassy polymers blended with a semi-crystalline polymer. Immiscible blends of PS/PP and PS/HDPE were prepared from commercially available polymers using melt processing and extrusion without additives. The weight fractions of the components were varied from 0 to 1. SEM analysis of the blends showed a range of morphologies over the composition range from small inclusions at low volume concentrations through intertwined co-continuous structures at specific intermediate compositions, and a reversal of this configuration at high volume fractions. The glass transition of the glassy polymer was measured with differential scanning calorimetry using the sensitive and high resolution modulated DSC method. A systematic change in glass transition of glassy polymers is observed as a function of composition in various immiscible polymer blends. Results show that the glass transition of polystyrene increases with a reduction in volume fraction, by approximately 5.4°C in polypropylene and 6.5°C in polyethylene. Probable models which might explain this effect are mentioned.

Several high temperature methods of processing Nafion® have been developed using various alkylammonium ion forms of the ionomer, and the choice of counterion has been shown to have a significant effect on the thermal and mechanical properties of this material. In particular, it has been shown that neutralization gives rises to two high-temperature mechanical relaxations as observed in dynamic mechanical analysis (DMA). While several studies in the literature have attempted to explain the molecular origins of these mechanical relaxations, the assignments were based primarily on limited DMA results and have at times been contradictory. The study presented here is a fundamental investigation into the molecular origins of the thermally induced morphological relaxations and dynamics of alkylammonium forms of Nafion® membranes as studied by variable temperature small-angle x-ray scattering (SAXS) and solid-state 19F NMR spectroscopy. The intensity of the small-angle ionomer peak at ca. q = 2 nm–1 was monitored as a function of temperature for each alkylammonium neutralized sample in unoriented and oriented states. In the case of the oriented samples, the degree of anisotropic scattering from the oriented ionomer morphology was quantified using the Hermann's orientation function and monitored as a function of temperature. Changes in intensity of the ionomer peak and the Hermann's parameter as a function of temperature were shown to correlate well with relaxations observed in DMA. Several variable temperature solid-state 19F NMR techniques (including spin diffusion, side-band analysis and T1ρ experiments) were used to investigate the dynamics of the Nafion® chains. Side band analysis indicated that the side-chain is more mobile than the main chain and that the mobility is greatly affected by the size of the counterion. Changes in side-band intensity as a function of temperature were shown to correlate well with DMA data. Results from T1ρ experiments show strong counterion dependence and suggest coupled main- and side-chain motions. A two-component relaxation process was also observed for the main-chain fluorines. The results of the NMR investigations, along with the SAXS data, have led to the development of a more detailed description of the dynamics of Nafion® and the molecular origins of the mechanical relaxations. With this information, the continuing goal to determine how the strength of the electrostatic interactions in perfluorosulfonate ionomers affects the chain dynamics and developing morphology may be realized for the purpose of controlling the morphology to create more efficient ionomeric membrane materials.