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High porosity and surface areas of ordered mesoporous materials provide substantial capacity for loading of guest molecules and the well-defined morphology of such materials can control their transport for controlled release. Here, the loading and release of mitoxantrone from unmodified ordered mesoporous carbon films is monitored using UV/Vis spectroscopy. Organic-organic self-assembly of Pluronic F127 with phenolic resin leads to interconnected elliptical pores (≈2 nm) in the film after carbonization. Interestingly, the total loading (2.6 ± 0.4 μg/cm(2)) and release of mitoxantrone is independent of film thickness (50–400 nm), suggesting diffusion limitations in pore filling. With alternative template, the pore size increases to ≈5 nm and the mitoxantrone loading increases to 3.5 ± 0.9 μg/cm(2), but the loading still remains thickness independent. Using phosphate buffered saline at 37 °C, less than 60 % of the loaded mitoxantrone is readily released from the mesoporous carbon films over a two-week period. The release profile includes an initial burst with a modest fraction (< 20 %) of the loaded drug released within the first day, followed by a near linear release over the subsequent 5–9 days. Interestingly, the smaller pores (ca. 2 nm) release nearly 50 % more mitoxantrone over 2 weeks than the larger pores (ca. 5 nm), despite the lower initial loading. These results illustrate potential limitations as well as opportunities for the use of highly hydrophobic porous materials for the controlled release of hydrophobic biologically active compounds as drug delivery systems.

We describe the synthesis and characterization of bicontinuous cubic poly(3,4-ethylenedioxythiophene) (PEDOT) conducting polymer gels prepared within lyotropic cubic poly(oxyethylene)10 nonylphenol ether (NP-10) templates with Ia3[combining macron]d (gyroid, GYR) symmetry. The chemical polymerization of EDOT monomer in the hydrophobic channels of the NP-10 GYR phase was initiated by AgNO3, a mild oxidant that is activated when exposed to ultraviolet (UV) radiation. The morphology and physical properties of the resulting PEDOT gels were examined as a function of temperature and frequency using optical and electron microscopy, small-angle X-ray scattering (SAXS), dynamic mechanical spectroscopy, and electrochemical impedance spectroscopy (EIS). Microscopy and SAXS results showed that the PEDOT gels remained ordered and stable after the UV-initiated chemical polymerization, confirming the successful templated-synthesis of PEDOT in bicontinuous GYR nanostructures. In comparison to unpolymerized 3,4-ethylenedioxythiophene (EDOT) gel phases, the PEDOT structures had a higher storage modulus, presumably due to the formation of semi-rigid PEDOT-rich nanochannels. Additionally, the storage modulus (G') for PEDOT gels decreased only modestly with increasing temperature, from ∼1.2 × 10(5) Pa (10 °C) to ∼7 × 10(4) Pa (40 °C), whereas G' for the NP-10 and EDOT gels decreased dramatically, from ∼5.0 × 10(4) Pa (10 °C) to ∼1.5 × 10(2) Pa (40 °C). EIS revealed that the impedance of the PEDOT gels was smaller than the impedance of EDOT gels at both high frequencies (PEDOT ∼10(2) Ω and EDOT 2-3 × 10(4) Ω at 10(5) Hz) and low frequencies (PEDOT 10(3)-10(5) Ω and EDOT ∼5 × 10(5) Ω at 10(-1) Hz). These results indicated that PEDOT gels were highly ordered, mechanically stable and electrically conductive, and thus should be of interest for applications for which such properties are important, including low impedance and compliant coatings for biomedical electrodes.

The production chemical industry currently lacks a comprehensive fundamental understanding of how polymeric oilfield water clarifiers work at the molecular level and which polymer components are most important for increasing field performance. The existing method for choosing a water clarifier involves a brute force approach, bottle testing as many products as possible, and includes a significant amount of trial and error. The study herein describes an approach in which a statistical library of acrylic polymers was used to develop a predictive model of performance for clarifiers in an Alkaline Surfactant Polymer (ASP) flooded reservoir in order to develop a customized polymer. A library of 50 acrylic polymers was synthesized and characterized with Asymmetric Flow Field Flow Fractionation (A4F). The polymers were evaluated for performance in three wells in an ASP flooded field by measuring the oil and grease remaining in the produced water after treatment. A three-step approach was taken to extract structure-property relationships. Principle Component Analysis was employed to reduce the dimensionality of the characterization properties. The principle components were then modeled using the polymer recipes in JMP/SAS. Finally, a model was developed to understand the field performance results in terms of the principle components. In the ASP Flood, the performance model indicated that the molecular weight of the acrylic polymers was the most important parameter for water clarifier performance in the three wells tested. The three evaluated wells showed significant variation in sensitivity to molecular weight, which emphasizes the importance of testing polymers in a representative sample of the wells within a reservoir when choosing a product. Importantly, our method of measuring residual oil and grease levels after treatment to evaluate performance was found to have a strong correlation with the ranking system employed by the field bottle testers. This study is one of the first examples of the determination of quantitative structure-property relationships for polymeric oilfield water clarifiers. By using this approach, one can identify the most important parameters for performance in a given field. Using the resulting predictive model, a customized water clarifier can be built for the field to give optimal performance.

Ion-conducting block copolymers (BCPs) have attracted significant interest as conducting materials in solid-state lithium batteries. BCP self-assembly offers promise for designing ordered materials with nanoscale domains. Such nanostructures provide a facile method for introducing sufficient mechanical stability into polymer electrolyte membranes, while maintaining the ionic conductivity at levels similar to corresponding solvent-free homopolymer electrolytes. This ability to simultaneously control conductivity and mechanical integrity provides opportunities for the fabrication of sturdy, yet easily processable, solid-state lithium batteries. In this review, we first introduce several fundamental studies of ion conduction in homopolymers for the understanding of ion transport in the conducting domain of BCP systems. Then, we summarize recent experimental studies of BCP electrolytes with respect to the effects of salt-doping and morphology on ionic conductivity. Finally, we present some remaining challenges for BCP electrolytes and highlight several important areas for future research. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 1–16

The controlled placement of gold nanoparticles (AuNPs) in poly(styrene-b-isoprene-b-styrene) [SIS] triblock copolymer thin films was achieved by tuning the surface chemistry of the AuNPs. Facile th...

We explored the relationship between ionic conductivities and morphology in a lithium perchlorate-doped poly(styrene-b-ethylene oxide) (PS–PEO) system using ac impedance spectroscopy, in situ small...

Soft templated mesoporous carbon films (ca. 60 nm thick) are fabricated by the cooperative assembly of poly(styrene-block-ethylene oxide) (PS-b-PEO) with phenolic resin, where the pore sizes are tuned by the addition of polystyrene oligomers (hPS) to this self-assembling system. Significant differences in the morphology and pore expansion are found for the thin films in comparison to previously reported bulk powders using a similar system. The film porosity is nearly independent of swelling agent content for addition of up to 10 wt % hPS; this limited effect is attributed to surface segregation of the hPS on the basis of wetting considerations, which decreases the effective concentration of hPS in the hydrophobic domains. The templated synthesis yields a relatively narrow pore size distribution for 10 wt % hPS. Elliptical pores are formed due to the uniaxial contraction that occurs during carbonization...

Nanoscale self-assembly of block copolymer thin films has garnered significant research interest for nanotemplate design and membrane applications. To fulfill these roles, control of thin film morphology and orientation is critical. Solvent vapor annealing (SVA) treatments can be used to kinetically trap morphologies in thin films not achievable by traditional thermal treatments, but many variables affect the outcome of SVA, including solvent choice, total solvent concentration/swollen film thickness, and solvent removal rate. In this work, we systematically examined the effect of solvent removal rate on the final thin film morphology of a cylinder-forming ABA triblock copolymer. By kinetically trapping the film morphologies at key points during the solvent removal process and then using successive ultraviolet ozone (UVO) etching steps followed by atomic force microscopy (AFM) imaging to examine the through-film morphologies of the films, we determined that the mechanism for cylinder reorientation from substrate-parallel to substrate-perpendicular involved the propagation of changes at the free surface through the film toward the substrate as a front. The degree of reorientation increased with successively slower solvent removal rates. Furthermore, the AFM/UVO etching scheme permitted facile real-space analysis of the thin film internal structure in comparison to cross-sectional transmission electron microscopy.

We demonstrate a simple, yet effective, mixed-salt method to increase the room temperature ionic conductivity of lithium-doped block copolymer electrolyte membranes by suppressing the crystalline phases in the conducting block. We examined a mixed-salt system of LiClO4 and LiN(SO2CF3)2 (LiTFSI) doped into a lamellae-forming poly(styrene-b-ethylene oxide) (PS–PEO) diblock copolymer. The domain spacings, morphologies, thermal behavior, and crystalline phases of salt-doped PS–PEO samples were characterized, and the ionic conductivities of block copolymer electrolytes were obtained through ac impedance measurements. Comparing the ionic conductivity profiles of salt-doped PS–PEO samples at different mixed-salt ratios and total salt concentrations, we found that the ionic conductivity at room temperature can be improved by more than an order of magnitude when coinhibition of crystallite growth is promoted by the concerted behavior of the PEO:LiClO4 and PEO:LiTFSI phases. Additionally, we examined the influence ...

We report the formation of a double-gyroid network morphology in normal-tapered poly(isoprene-b-isoprene/styrene-b-styrene) [P(I-IS-S)] and inverse-tapered poly(isoprene-b- styrene/isoprene-b-styrene) [P(I-SI-S)] diblock copolymers. Our tapered diblock copolymers with overall poly(styrene) volume fractions of 0.65 (normal-tapered) and 0.67 (inverse-tapered), and tapered regions comprising 30 volume percent of the total polymer, were shown to self-assemble into the double-gyroid network morphology through a combination of small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). The block copolymers were synthesized by anionic polymerization, where the tapered region between the pure poly(isoprene) and poly(styrene) blocks was generated using a semi-batch feed with programmed syringe pumps. The overall composition of these tapered copolymers lies within the expected network-forming region for conventional poly(isoprene-b-styrene) [P(I-S)] diblock copolymers. Dynamic mechanical analysis (DMA) clearly demonstrated that the order-disorder transition temperatures (T(ODT)'s) of the network-forming tapered block copolymers were depressed when compared to the T(ODT) of their non-tapered counterpart, with the P(I-SI-S) showing the greater drop in T(ODT). These results indicate that it is possible to manipulate the copolymer composition profile between blocks in a diblock copolymer, allowing significant control over the T(ODT), while maintaining the ability to form complex network structures.

The phase behavior of lithium salt-doped poly(styrene-b-ethylene oxide) (PS−PEO) was studied as a function of salt concentration, lithium (Li) counterion (X), and annealing temperature. Three LiX salts were employed in this work: LiClO4, LiCF3SO3, and LiAsF6. Increasing the salt doping ratio ([EO]:[Li]) from 48:1 to 3:1 led to morphological changes from hexagonally packed cylinders to lamellar morphologies; however, comparison between the small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) results shows that the location of these morphological changes are altered by the different counterions. We interpret our SAXS, TEM, and differential scanning calorimetry data using strong segregation theory to estimate an effective interaction parameter (χeff) for our salt-doped copolymers. This χeff varies linearly with salt concentration for a single PS-PEO:LiX material; however, the slope for each χeff,PS−PEO:LiX is influenced by the nature of the counterion. We rationalize these effects b...