Search

Integration of polycyclic aromatic hydrocarbon (PAH) units into semi-fluorinated polymers affords high thermal stability and excellent processability for potential applications in optoelectronic, gas-separation, and advanced composites.

Transparent, film-forming fluorinated arylene vinylene ether (FAVE) polymers with enchained triarylamine (TAA) moieties were prepared and characterized. Control over fluoro-olefin content within the backbone, as a function of base, was confirmed and postpolymerization dehydrofluorination was shown to increase fluoroolefin content from 5 to 31 mol %. Thermal cross-linking was found to occur approximately 100 °C lower than in traditional FAVE polymers (ca. 160 °C). Electrochemical analysis demonstrated the enchained TAA retained its established electrochemical character. The latent reactivity of the TAA was explored via electrophilic aromatic substitution and formylation reactions toward precise functionalization for specific electro-optic applications and others.

Perfluorocycohexenyl (PFCH) aromatic ether polymers were synthesized by step-growth polycondensation of polycyclic aromatic hydrocarbon (PAH) bisphenols and decafluorocyclohexene (DFCH) affording a new class of unsaturated semi-fluoropolymers containing the rigid PAH linkage. Two acenaphthenequinone and two phenanthrenedione derived PAH bisphenols underwent base-mediated step-growth vinyl addition/elimination polymerization with DFCH to give polymers with well-defined unsaturation, moderate molecular weights, and variable glass transition (Tg) and thermal decomposition (Td) temperatures based on the starting PAH bisphenol monomer. With one exception exhibiting a low degree of crystallinity, PFCH polymers with PAH bisphenols were amorphous with Tg ranging from 184 to 240 °C. The new polymers contain intact unsaturation and reactive PAH moieties amenable for selective post-polymerization functionalization and crosslinking.

This study examines perfluorocyclobutyl (PFCB) aromatic ether polymers and demonstrates, for the first time, their potential as corrosion-resistant coatings. PFCB polymers are a distinct class of semi-fluorinated polymers that are based on thermal cyclopolymerization of aromatic trifluorovinyl ethers. They combine the flexibility and thermal stability of aromatic ethers with strong fluorocarbon linkages. Electrochemical impedance spectroscopy and potentiodynamic scans reveal that PFCB coatings display protective barrier properties against corrosion attack nearly equal to that of polyvinylidene fluoride (PVDF) coatings. The PFCBs also show excellent adhesion to metal surfaces and nonstick properties comparable to that of PVDF. Combined with their high thermal resistance, PFCBs may lead to new corrosion-resistant coatings in marine, oil and gas, and other applications.

Many desirable characteristics of polymers arise from the method of polymerization and structural features of their repeat units, which typically are responsible for the polymer’s performance at the cost of processability. While linear alternatives are popular, polymers composed of cyclic repeat units across their backbones have generally been shown to exhibit higher optical transparency, lower water absorption, and higher glass transition temperatures. These specifically include polymers built with either substituted alicyclic structures or aromatic rings, or both. In this review article, we highlight two useful ring-forming polymer groups, perfluorocyclobutyl (PFCB) aryl ether polymers and ortho-diynylarene- (ODA) based thermosets, both demonstrating outstanding thermal stability, chemical resistance, mechanical integrity, and improved processability. Different synthetic routes (with emphasis on ring-forming polymerization) and properties for these polymers are discussed, followed by their relevant applications in a wide range of aspects.

Three classes of semi-fluorinated aromatic ether polymers, namely: perfluorocyclobutyl (PFCB), perfluorocycloalkenes (PFCA), and fluorinated arylene vinylene ether (FAVE), which are mostly amorphous have been reported via step-growth polymerization of fluoroalkenes. Unlike traditional fluoropolymers which have higher degree of crystallinity and are plagued by lack of solubility in common organic solvents, these uncured semi-fluorinated polymers are readily soluble in most organic solvents resulting in improved processability. In addition, all three semi-fluorinated polymers are versatile and can be custom-designed and fabricated into linear, telechelic, alternating and segmented-block, and network polymers, facilitating applications in optics, optoelectronic, photonics, proton exchange membranes, sensors, and fuel cells. Major aim of this timely review is to provide account of synthetic opportunities these semi-fluorinated offer in various applications.

Many desirable characteristics of polymers arise from the method of polymerization and structural features of their repeat units, which typically are responsible for the polymer’s performance at the cost of processability. While linear alternatives are popular, polymers composed of cyclic repeat units across their backbones have generally been shown to exhibit higher optical transparency, lower water absorption, and higher glass transition temperatures. These specifically include polymers built with either substituted alicyclic structures or aromatic rings, or both. In this review article, we highlight two useful ring-forming polymer groups, perfluorocyclobutyl (PFCB) aryl ether polymers and ortho-diynylarene- (ODA) based thermosets, both demonstrating outstanding thermal stability, chemical resistance, mechanical integrity, and improved processability. Different synthetic routes (with emphasis on ring-forming polymerization) and properties for these polymers are discussed, followed by their relevant applications in a wide range of aspects.

Epoxy resins are one of the most widely used thermosetting materials in industrial and practical applications because they exhibit excellent mechanical, thermal, and dielectric performance at commodity volume and cost. In particular, multifunctional epoxies—dense and cross-linked structured resins—are used as molding compounds, sealants, and protective coatings for many barrier-related applications. In this work, we used a tetrafunctional epoxy-amine resin as a coating for mild steel and used electrochemical impedance spectroscopy (EIS) to investigate its protection performance in a 3.5 wt % NaCl solution. The results indicate that the coating was able to resist corrosion and maintain a very high impedance modulus for more than 30 d of continuous exposure to the NaCl solution. Different resistance behaviors, as indicated by EIS, were observed for the coatings with artificially introduced damage. The coating also showed high thermal resistance and good adhesion to mild steel surfaces. This tetrafunctional epoxy-amine resin could effectively function as a high performance and corrosion resistant coating material for semiconductor, aerospace, and marine applications.

Many organic corrosion inhibitors are complex and may include complicated chemical structures, mixture of different species, or require numerous and tedious preparation steps. In this study, we demonstrate inhibition by triazole- and imidazole-based compounds, which are synthesized in a one-step method and possess austere chemical structures. The inhibition effect was studied on the corrosion of mild steel in 1.0 M HCl solution at 40 °C by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, and weight loss. Results from electrochemical measurements showed that the aromatic compounds were effective in inhibiting corrosion in acidic medium, such that the inhibition efficiency increased with increasing inhibitor concentration. The triazole-based compound had the best inhibitive performance (efficiency >90%), followed by the imidazole-based (~85%), at a concentration of 850 μM. These results were supported by analyses obtained from scanning electron and atomic force microscopy, which showed improved mild steel topology and decrease in surface roughness by up to a factor of five, and x-ray diffraction, which revealed the extent of oxide layer formation. In addition, the adsorption of a protective inhibitor layer on the metal surface was confirmed by Raman spectroscopy, while the underlying mode and mechanism were postulated based on a Langmuir adsorption isotherm and computational studies, which showed good correlation between the inhibitive ability and the electron donating and accepting capability of the compounds.

Semi-fluorinated arylene vinylene ether (FAVE) telechelomers and their chain extended PFCB polymers were synthesized via base catalyzed step-growth polymerization of polycyclic aromatic hydrocarbon (PAH) bisphenols and commercially available 4,4ꞌ-bis(4-trifluorovinyloxy)biphenyl (TFVE-BP) monomer. Soluble polymers were obtained in good yield, gave transparent free-standing films, and were characterized by 19F NMR, TGA, DSC, GPC, water contact angle and AFM. Thermal analysis by differential scanning calorimetry (DSC) revealed Tg values ranging from 150 to 168 °C. The new polycyclic aromatic FAVE polymers possess intact trifluorovinyl ether (TFVE) end groups susceptible to thermal chain extension leading to perfluorocyclobutyl (PFCB) aryl ether polymers with Tg ranging from 149 to 174 °C. Semi-fluorinated telechelic polymers with controlled terminal and enchained unsaturation with latent crosslinking ability may find use in specialty applications such as photonics or gas separation technologies.

The effects of compounded hydrogenated–fluorinated surfaces formed by perfluorocyclobutane (PFCB)-containing polymers on the alignment of 4,4′-octylcycanobiphenyl (8CB), a liquid crystal that exhibits both nematic and smectic phases, were investigated. The inherent segregation between fluorine- and hydrogen-rich segments produced structured interfaces with fluorinated and protonated nano domains. The morphologies of the interfaces and their corresponding surface energies were probed by AFM and the alignment of 8CB was investigated by polarized optical microscopy. We found that varying the fluorine content controlled both the structure and the interfacial morphology. The 8CB layer orientation was strongly affected by the interracial energies. With increasing fluorine content the homeotropic alignment temperature range of 8CB in the nematic phase was increased and that of the smectic phase was hardly affected. The impact observed was attributed to competition between anchoring effects and elasticity of the LC layers.

Suzuki polycondensation (SPC) as an alternative strategy has been utilized for the first time to readily yield functional perfluorocyclobutyl (PFCB) aryl ether polymers, which are difficult to obtain via the traditional [2+2] thermal cyclopolymerization strategy. Using two reactive PFCB aryl ether molecules as monomers, the biphenyl PFCB aryl ether polymer without any functionality was first prepared and exhibited good thermal stability, up to 450 °C at 8% weight loss (N2). By choosing appropriate functional monomers, aldehyde-functionalized PFCB aryl ether polymer precursor was also successfully prepared. Post-polymerization modification of this polymer precursor via Knoevenagel condensation yielded three distinct PFCB aryl ether polymers containing thermally stable triarylamine-based electro-optic chromophores.

A novel partially fluorinated arylene vinylene ether (FAVE) polymer containing ester groups was synthesized, which was used to prepare three reactive FAVE polymers containing carboxylic acid groups, alcohol groups, and acid chloride groups, respectively. Post-polymerization modifications of the FAVE polymer's carboxylic acid groups (via a DCC coupling procedure with the desired alcohol), alcohol groups (via DCC coupling or an acid chloride esterification procedure with the desired carboxylic acid or acid chloride), and acid chloride groups (via an optimized nucleophilic substitution reaction with the desired alcohol or amine) were successfully performed. Several examples have been successfully prepared to demonstrate the versatility of these developed modification methods. FAVE polymers have been prepared with NHS active ester groups, Disperse Red 1 chromophores, benzyl bromide groups, aryl trifluorovinyl ether groups, ATRP initiator groups, vinyl groups, propargyl groups, Disperse Orange 3 chromophores, and benzaldehyde groups. In most cases, analytical data are consistent with a quantitative conversion of the reactive or functional groups. It is demonstrated that no degradation of the FAVE polymer matrix occurs after multistep post-polymerization modification reactions.

Here the microscopic mechanism that leads to the surprising formation of a nanopattern upon methanol reacting with a H-terminated Si(111) surface [Michalak et al., Nat. Mater. 2010, 9, 266–271] is reinvestigated from both theory and experiment. First-principles calculations determine the fully OCH3-terminated Si(111) surface as the thermodynamic ground state in the presence of methanol, seemingly in contrast to the experimentally found nanopattern. At 65 °C the presence of H2 initiates desorption of the methoxy groups and thereby leads to a dynamic equilibrium of the reaction of methanol with the H-terminated Si(111) surface, which is a 1/3 OCH3-terminated and 2/3 H-terminated Si(111) surface, with all OCH3 groups standing as NNNs, corresponding to the nanopattern observed earlier. Investigating fluorine group termination of Si(111) as a test system the present study demonstrates that the combination of theoretical and experimental techniques used here is in fact sufficiently sensitive to resolve complex ...

A series of biphenyl per fluorocyclobutyl (BP-PFCB) polyethylene glycol (PEG) copolymers were prepared by nucleophilic addition the hydroxyl end groups of PEG to trifluorovinyl ether (TFVE) end groups of biphenyl perfluorocyclobutyl (BP-PFCB) oligomers. Upon addition, copolymers are linked through a new fluorinated arylene vinylene ether (FAVE) bond. Resulting copolymers were characterized by ATR-FTIR, 1H, and 19F NMR analysis. Gel permeation chromatography (GPC) showed a number-average molecular weights (M n s) of polymers from 9000 to 16,000. A moderated increase in M n s was observed compared to corresponding oligomers. Differential scanning calorimetry (DSC) thermograms revealed glass transition temperatures (T gs) from −25 to 127 °C. All copolymers showed one copolymer-specific T g. All T gs were compared to the theoretical values calculated from the Fox equation. Comparisons showed T gs became more agreeable at the lowest and highest PEG weight fractions. Thermal gravimetric analysis (TGA) studies showed a two-stage degradation in nitrogen and air that corresponded to copolymer weight percent. The onsets of degradations were from 343 to 360 °C for copolymers in air and from 333 to 343 °C for copolymers in nitrogen.

Background:Parents represent a key ecological component in influencing their child’s physical activity. The aim of this exploratory study was to assess the relationship between maternal acculturation and physical activity in Hispanic children.Methods:102 Hispanic mothers (mean age 36.2 yrs; +SD 7.3 yrs) and their children (mean age 10.0 yrs, +SD 0.8 yrs) participated. Most of the mothers (74%) were foreign-born, with 62% classified as low acculturated and 38% high acculturated. Demographic, acculturation, and anthropometric measures were completed by mothers and children. Physical activity was measured using accelerometers. Relationships between maternal acculturation and demographic variables and children’s physical activity were examined using chi-square, Analysis of Variance, and simple regression.Results:Children had higher physical activity levels than their mothers (t(49) = −7.87, P < .0001). Significant correlations between maternal and child’s physical activity levels were observed in moderate (r2 = 0.13, P = .001), vigorous (r2 = 0.08, P = .05), and moderate-to-vigorous physical activity (r2 = 0.17, P = .002). Low acculturated mothers were more likely to have active children compared with high acculturated mothers. Maternal BMI and other demographic characteristics were not significantly associated with child’s physical activity.Conclusions:Findings from this study revealed an association among maternal acculturation, role modeling, and child’s physical activity.

A method for the preparation of AB-type monomers with complimentary fluoro-olefin and phenol functionalities is described. The three-step process is amenable to commercial scale up and uses widely-available, commercial reagents including bisphenols and perfluorocycloalkene (PFCA) compounds. Title compounds and intermediates were characterized via multi-nuclear NMR and FT-IR spectroscopy providing structural and mechanistic elucidation of PFCA step-growth polymerizations. The formation of vinyl and allyl substituted products were quantified and shown to be dependent on PFCA ring size and reaction medium. Nearly equal amounts of vinyl- and allyl-substituted products were observed with perfluorocyclohexene (PFCH) while 2–11% allyl-substitution was observed with perfluorocyclopentene (PFCP), depending on reaction medium polarity. Previous PFCA research and characterization of title compounds suggests that fluoride-catalyzed rearrangement is primarily responsible the formation of two substitution products. Polymerization of an AB-type monomer derived from bisphenol A is demonstrated and was shown to reproducibly result in film-forming polymers with higher molecular weights than previously described methods.

The fluorination of graphite/graphite oxide (GO) and their derivatives has been widely investigated for how fluorine interacts with sp2/sp3 carbon; however, the mechanism of this interaction has not yet been elucidated. Fluorination of GO (FGO) at either 10 or 15 psi for 24 h, produced two new absorption bands at ∼743 cm−1 and 482 cm−1, and are attributed to the presence of out-of-plane surface fluorine bonds in FGO (absent in fluorographite – FG). IR studies confirmed the stability of the formed C–F bonds and defect formation due to the introduction of oxyfluorinated species into the graphitic carbon through fluorination of epoxides. Fluorination of GO resulted in ∼4–5 times more fluorine incorporation in bulk as compared to FG. (4.57 vs. 0.8 at.% and 6.64 vs. 1.4 at.% at 10 and 15 psi, respectively). PXRD analyses also showed that the interlayer spacing of FGO expanded in the presence of intercalated C–F species and a defect formation was observed with the evidence of increase of the ID/IG ratio from Raman spectra. To this end, understanding the origin of surface C–F bonds and structural changes in FGO therefore leads to new applications such as implementation of FGO for sensing, nano-electronics and energy storage.

A variety of perfluorocycloalkenyl (PFCA) aryl ether monomers and polymers with enchained triarylamine units were successfully synthesized, characterized and reported here. These polymers are highly thermally stable and show variable thermal properties. Successful conversion of the newly synthesized TAA enchained perfluorocyclopentenyl (PFCP) aryl ether polymers via formylation and EAS demonstrates the synthetic versatility of TAA moiety and provides an excellent option for application specific post polymerization reactions. The cross-linking behavior of PFCP aryl ether polymers was studied under different reaction conditions. The combination of processability, thermal stabilities, and tailorability makes these polymers suitable for a wide variety of applications including electro-optics, proton exchange membranes and super-hydrophobic applications.

Platinum catalysts for electrochemical oxygen reduction were prepared on mesoporous carbon supports, some of which included embedded zirconia nanoparticles, by borohydride reduction of hexachloroplatinic acid in ethylene glycol solution. The resulting materials are approximately 20 percent platinum by weight and consist of platinum particles having diameters in the 2-3 nm range, evenly distributed throughout the support structure. Electrochemical surface areas for platinum were measured by hydrogen adsorption/desorption and carbon monoxide stripping and were found to be lower for platinum on carbon containing zirconia than for carbon without zirconia. This finding is thought to reflect a slightly larger platinum particle size and also a higher degree of particle aggregation for platinum on the carbon support containing zirconia, possibly caused by localized patches of positive charge on zirconia particles under the acidic conditions used to deposit platinum. Zirconia-containing carbon supports that had been treated with platinum were subsequently treated with polymer electrolytes having terminal aryl phosphonate groups that can covalently bind to exposed zirconia sites, thereby producing composite materials having intimately integrated platinum catalysts and polymer electrolytes immobilized within a mesoporous carbon support structure. Electrochemical ORR activity of these materials as thin-film electrodes was assessed using rotating disk electrode voltammetry in aqueous sulfuric acid solutions. Activity for platinum on a mesoporous carbon support without zirconia is comparable to that of benchmark materials, e.g., platinum on Vulcan carbon XC-72, but is diminished on the mesoporous carbon support containing zirconia. Remarkably, the platinum ORR activity is fully recovered and slightly enhanced on zirconia-containing supports following treatment with polymer electrolyte. Possible reasons for the recovery of the platinum ORR activity upon polymer electrolyte treatment, and implications for possible application in polyelectrolyte membrane fuel-cell technology, are discussed.

Objective To assess the frequency and risk factors for return to the primary acute care service among patients with lymphoma undergoing inpatient rehabilitation. Design Retrospective study. Setting Tertiary referral-based cancer center. Patients All patients with a history of lymphoma admitted to an inpatient rehabilitation between October 1, 2003, and January 30, 2013. Main Outcome Measures Items analyzed from patient records included return to the primary acute care service with demographic information, lymphoma characteristics, medications, hospital admission characteristics, and laboratory values. Results A total of 143 unique patient admissions were analyzed, and 54 of these 143 lymphoma inpatient rehabilitation admissions (38%) returned to the primary acute care service. However, 16 of 54 (30%) returned because they needed additional chemotherapy. Excluding patients who returned to the primary acute care service for chemotherapy, statistically significant or approaching statistically significant factors ( P P = .0002), male gender ( P = .001), history of hematopoietic stem cell transplantation ( P = .0355), and presence of an intravenous antifungal agent ( P = .0717). Of the patients transferred back to the primary acute care service, 13 of 38 (34%) were discharged directly home, 10 of 38 (26%) died in the hospital, 7 of 38 (18%) were transferred to a subacute rehabilitation facility, and 4 of 38 (11%) were transferred to inpatient rehabilitation. Conclusions When excluding patients who returned for chemotherapy, patients with lymphoma who were male, had undergone hematopoietic stem cell transplantation, and had a creatinine level ≥1.3 mg/dL demonstrated increased risk for return to the primary acute care service.

A series of N-alkyl/aryl carbazole 3,6-substituted arylene trifluorovinyl ether (TFVE) monomers were synthesized in high purity and yield from a concise four-step synthesis using carbazole as a starting material. Condensate-free, step-growth chain extension of the monomers afforded perfluorocyclobutyl (PFCB) arylene ether homo- and copolymers as solution processable, optically transparent blue-light emissive materials. Arylene TFVE monomers and conversion to PFCB arylene ether polymers were structurally elucidated and purity confirmed by high resolution mass spectroscopy, NMR (1H, 13C, and 19F) spectroscopy, gel permeation chromatography, and attenuated total reflectance Fourier transform infrared analysis. Thermal analysis by differential scanning calorimetry and thermogravimetric analysis revealed glass transition temperatures >150 °C and onset of decomposition in nitrogen >410 °C with 40 wt % char yield up to 900 °C. Optical and electrochemical studies included solution (tetrahydrofuran) and solid state (spin cast thin film) UV–vis/fluorescence spectroscopy and cyclic voltammetry which showed structure dependence of these blue emissive systems on the nature of the N-alkyl/aryl carbazole substitution in either homo- or copolymer configurations. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 552–560

A novel class of semifluorinated perfluorocyclohexenyl (PFCH) aryl ether homo/copolymers was successfully synthesized with high yield through the step-growth polymerization of commercially available bisphenols and decafluorocyclohexene in the presence of a triethylamine base. The synthesized polymers exhibit variable thermal properties depending on the functional spacer group (R). PFCH aryl ether copolymers with random and alternating architectures were also prepared from versatile bis-perfluorocyclohexenyl aryl ether monomers. The PFCH polymers show high thermal stabilities with a 5% decomposition temperature ranging from 359 to 444 °C in air and nitrogen atmosphere. These semifluorinated PFCH aromatic ether polymers contain intact enchained PFCH olefin moieties, making further reactions such as crosslinking and application specific functionalization possible. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 232–238

Several distinctive factors support the argument for developmentally appropriate youth tobacco cessation programs, including the science of adolescents’ evolving brains, as well as the incidence and risks of adolescent tobacco use, and its endemic nature in adolescent milieus and culture. This paper utilizes these factors and insights from the Youth Tobacco Awareness Program (YTAP), a cognitive-behavioral adolescent tobacco cessation program, to support 5 opportunities for developmentally and ecological-based tobacco cessation programs for youth. These opportunities include the continuing need for tobacco cessation, adolescents’ desire to quit tobacco, the need for effective youth tobacco cessation strategies amid broader-based community efforts, and the support of scientific research for program effectiveness. In our experience, the conundrum of youth tobacco use has presented these opportunities for debate, research, and development of enhanced, appropriate, and more effective models of cessation delivery.

A unique class of perfluorocycloalkenyl (PFCA) aryl ether monomers was synthesized from commercially available perfluorocycloalkenes (PFCAs) and bisphenols in good yields. This facile one pot reaction of perfluorocycloalkenes, namely, octafluorocyclopentene (OFCP), and decafluorocyclohexene (DFCH), with bisphenols occurs at room temperature via an addition–elimination reaction in the presence of a base. The synthesis of PFCA monomers and their condensation with bisphenols lead to perfluorocycloalkenyl (PFCA) aryl ether homopolymers and copolymers with random and/or alternating polymer architectures.

Commercially available recycled ground rubber tire (GRT) particles, found to contain persistent mechano-free radicals confirmed by electron paramagnetic spectroscopy for the first time self-initiates free radical polymerization of acrylic acid (AA). The poly acrylic acid (PAA) grafted GRT (PAA-g-GRT) was confirmed by Attenuated Total Reflection Fourier Transform Infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis (TGA). Epoxy composites using the PAA-g-GRT as filler were prepared and their mechanical properties were studied. The PAA-g-GRT/epoxy composite showed higher mechanical properties with an increase of modulus up to 180% as compared with the neat GRT/epoxy composite. Surface morphology of GRT, neat GRT/epoxy, and PAA-g-GRT/epoxy composites were analyzed by scanning electron microscopy. This technology introduces a new concept to functional and reactive recycling and the cost effective utilization of renewable resource green materials. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers

Objective To assess the frequency and reasons for return to the primary acute care service among leukemia patients undergoing inpatient rehabilitation.

The curing behavior of diglycidyl ether of bisphenol A (DGEBA) epoxy and specially ground mechanochemical devulcanized ground rubber tire system (GRT) in the presence of polyoxyalkyleneamine curing agent was investigated by non-isothermal differential scanning calorimetry technique at different heating rates. Scanning electron microscopic-energy dispersive X-ray spectroscopy, and attenuated total reflection infrared spectroscopy were used to characterize the GRT particles. The kinetic parameters of curing process were determined by isoconversional method given by Malek. The average activation energy E a was found to be 52.3–60.7 and 45–59.2 kJ/mol for neat epoxy amine (Epo am 31) and epoxy/amine with GRT (5 Epo am 31) systems, respectively. It was observed that the presence of GRT in epoxy/amine promotes the curing. A two parameter (m, n) autocatalytic model (SB equation) was found to be the most adequate to describe the cure kinetics of the studied epoxy/GRT system. A dominant catalyzing effect of GRT on the curing reaction was observed which is attributed to the complexity of the reaction at later stages of curing, therefore, it was not possible to model the reaction over the whole range of degree of conversion.

A new class of partially fluorinated alternating aryl/alkyl vinylene ether (FAVE) polymers were prepared from addition polymerization of aryl trifluorovinyl ethers (TFVEs) with 1,4-butanediol or 4-hydroxybenzyl alcohol. Monodisperse FAVE telechelic polymers were also prepared possessing latent thermal reactivity which afforded chain-extended perfluorocyclobutyl (PFCB) aryl ethers via step-growth [2 + 2] cyclodimerization of the aryl TFVEs. Both linear and PFCB chain-extended FAVE polymers produced thermally robust, optically transparent, flexible spin-cast films. The FAVE polymers and their telechelic polymers were characterized using 19F NMR and 1H NMR complemented with molecular weight analysis using gel permeation chromatography and thermal analysis employing differential scanning calorimetry and thermogravimetry. © 2013 Society of Chemical Industry

Objective To evaluate the effectiveness of an educational intervention designed to reduce traumatic brain injury (TBI)–related misconceptions among blacks and Latinos with complicated mild to severe TBI. Design Randomized controlled trial with masked 1-month follow-up. Setting Community. Participants Persons (N=52) with complicated mild to severe TBI (mean best day 1 Glasgow Coma Scale score, 11.27±3.89) were randomly recruited from 141 eligible participants (mean age, 37.71±13.88y; age range, 19–66y; mean months postinjury, 24.69±11.50); 25 participants (48.1%) of participants were black and 27 (51.9%) were Hispanic/Latino. Of the Hispanic/Latino participants, 18 (66.7%) were non-U.S. born and 12 (44.4%) spoke Spanish as their primary language. Twenty-seven individuals were randomized to the educational intervention group and 25 were randomized to the wait-list control group. Interventions Single-session educational intervention with written materials provided in English or Spanish. Main Outcome Measures Forty-item Common Misconceptions about Traumatic Brain Injury Questionnaire administered at baseline and 1-month follow-up. Results After controlling for ethnic and language differences, a significant between-group main effect ( P =.010) and a significant time-group interaction for the Common Misconceptions about Traumatic Brain Injury Questionnaire were noted (Wilks Λ =.89; F 1,46 =6.00; P =.02). The intervention group showed a decrease in TBI misconception percentages, whereas the wait-list control group maintained similar percentages. At 1-month follow-up, the wait-list control group reported more misconceptions than did the intervention group ( P =.019). Conclusions An educational intervention developed to address the recovery process, common symptoms, and ways to handle the symptoms provides promise as a tool to decrease TBI misconceptions among persons from ethnically and educationally diverse backgrounds. The effects of therapist characteristics and the client-therapist relation on outcomes should be further explored.

Background Pancytopenia, immunosuppression, and other factors may place patients with multiple myeloma at risk for medical complications. These patients often require inpatient rehabilitation. No previous studies have looked at risk factors for return to the primary acute care service of this patient population. Objective To determine the percentage of and factors associated with return to the primary acute care service of multiple myeloma rehabilitation inpatients. Design Retrospective review. Setting Acute inpatient rehabilitation unit within a National Cancer Institute Comprehensive Cancer Center. Participants All patients with multiple myeloma admitted to the inpatient rehabilitation unit between March 1, 2004, and February 28, 2015. Main outcome measures Return to the primary acute care service was analyzed with demographic information, multiple myeloma characteristics, medications, laboratory values, and hospital admission characteristics. Results One hundred forty-three inpatient rehabilitation admissions were found during the study period. After we removed multiple admissions of the same patients and planned transfers to the primary acute care service, 122 admissions were analyzed. Thirty-two (26%) patients transferred back to the primary acute care service for unplanned reasons. Multivariate analysis revealed male gender and thrombocytopenia as significantly associated with return to the primary acute care service. The median survival of patients who transferred back to the inpatient primary acute care service was 180 days versus 550 days for those who did not (P Conclusion Because of their medical fragility, clinicians caring for rehabilitation inpatients with multiple myeloma should maintain close contact with the primary oncology service. Factors associated with an increased risk of transfer back to the primary acute care service include male gender and thrombocytopenia. Level of evidence IV.

Aim: To determine whether symptom burden at the time of admission to inpatient rehabilitation is predictive of functional improvement in cancer rehabilitation inpatients. Methods: Retrospective review of medical records at a tertiary referral-based cancer centre of all patients admitted to an inpatient rehabilitation unit between 1 March 2013 and 20 May 2013. The medical records for 71 unique cancer rehabilitation inpatients were analysed. Outcome measures included the Edmonton Symptom Assessment System and Functional Independence Measure. Results: Statistical analysis of total admission Edmonton Symptom Assessment System scores and total change in Functional Independence Measure scores found no significant relationships. The symptom burden of patients was mild. Patients demonstrated statistically significant improvements in symptoms and function during inpatient rehabilitation. The mean change in total Edmonton Symptom Assessment System and total Functional Independence Measure scores was a decrease of 7.41 and an increase of 19.20, respectively. Statistically significant changes occurred in fatigue, sleep, pain and anxiety. Conclusions: Both symptom and functional scores improved significantly during inpatient rehabilitation. However, no significant relationships were found between symptoms at admission and improvements in Functional Independence Measure score.

Carbon nanofibers were prepared using electrospinning and thermal treatment of a new precursor, poly(acrylonitrile-co-vinylimidazole). Raman spectroscopy confirmed carbonization. Steam activation resulted in high surface area of 1120 m2/g. Coin cells were assembled using ethylmethylimidazolium bis(trifluoromethylsulfonyl) imide (EMITFSI) as the electrolyte. Cyclic voltammetry showed classic box-like behavior of electrochemical double layer capacitors with specific capacitances ranging between 122 F/g (10 mV/s) and 86 F/g (300 mV/s). From Ragone plots, the maximum energy and power densities were 47.4 Wh/kg (0.5 A/g) and 7.2 kW/kg (5 A/g), respectively. Keywords: Carbon nanofibers, Supercapacitors, Copolymers, Electrospinning

Surface modification of ground rubber tire (GRT) was performed by bulk polymerization of acrylic acid (AA) without using any initiator. Two different sizes of GRT were used for this project: 40 mesh (often used in Asphalt Industry), and 300 mesh which is used in other industries. The concentration of the monomer (acrylic acid), reaction temperature and the reaction time (1 and 3 h) are important factors on the grafting degree – especially because our goal was not to use any initiator during the reaction (there are well known procedures for grafting of polymers by using different type of initiators). Our effort was towards simplifying the grafting process and to make it much faster and less expensive (more acceptable by the industry). The microstructural and morphological changes of the GRT particles were characterized by Attenuated Total Reflectance Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), viscosity test of the modified asphalt binder [PG 64-22 asphalt binder with virgin GRT particles (40 and 300 mesh), and PG 64-asphalt binder with AA treated GRT particles of the same size]. Dynamic shear rheometer (DSR) test of the modified asphalt binder was also performed. Thermal gravimetric analysis (TGA) was investigated on untreated and AA treated 300 mesh GRT particles. Results showed that with the addition of surface modified GRT particles increased the viscosity and failure temperature values of asphalt binder regardless of binder source and grade.

Nitric oxide (NO) plays an important role in physiological functions in the body, naturally synthesized by nitric oxide synthase. NO was discovered as the endothelium-derived relaxing factor, allowing for vasodilation to occur in blood vessels, thus preventing platelet aggregation. It is also known as an antimicrobial agent. As it has been shown to enhance wound healing, recent efforts have been made to incorporate NO into thromboresistant polymers for medical devices. In this work, an acrylonitrile-co-1-vinylimidazole (AN/VIM) copolymer was melt-spun to produce a surgical suture type material with high durability and tensile strength which can store and release NO. The acrylonitrile (AN) comonomers are stabilized in the melt-spinning process, allowing for the formation of the NO molecular donor group, a diazeniumdiolate or NONOate. When AN/VIM is reacted with NO, the NONOate will form on AN segments. Each NONOate releases two molar equivalents of NO upon reaction with a proton source. The fiber mechanica...

A statically non-wetting, electrospun surface of non volatile room temperature ionic liquid (RTIL), 1-butyl-3-methylimidazolium hexafluorophosphate, (BMIM-PF 6 ), hosted in a solution-processable, semi-fluorinated perfluorocyclobutyl (BP-PFCB) aryl ether polymer was successfully prepared by electrospinning and compared with a surface prepared by spin casting. The surface properties of undoped and BMIM-PF 6 doped systems were analyzed by water contact angle (WCA) and atomic force microscopy (AFM). BMIM-PF 6 doped BP-PFCB surfaces prepared by spin casting showed a WCA of 90° while non-woven electrospun surfaces with the same BMIM-PF 6 concentration showed high degree of hydrophobicity with a WCA greater than 150°. Morphologies of the electrospun surfaces were characterized by scanning electron microscopy (SEM). The surface composition was analyzed by energy-dispersive X-ray spectroscopy (EDXS) and attenuated total reflectance infrared spectroscopy (ATR-IR). Thermal analysis of the electrospun, non-woven surfaces of the doped and the undoped system of BP-PFCB were done by TGA.

A new method for the surface modification of used tire rubber (UTR) is being developed. The method involves hydrosilylation of ground UTR particles with trichlorosilane (TCS) under various reaction conditions. The reaction has been carried out with and without solvents and catalysts (Karsted's/Pt catalyst). TCS treated UTR particles are then hydrolyzed to obtain silanol functionalized hydrosilylated rubber powder. Attenuated total reflection–Fourier transform infrared, solid-state 13C NMR spectroscopy, and thermogravimetric analysis are provided as evidence of hydrosilylation onto rubber particles.

A unique class of aromatic ether polymers containing perfluorocyclopentenyl (PFCP) enchainment was prepared from the simple step growth polycondensation of commercial bisphenols and octafluorocyclopentene (OFCP) in the presence of triethylamine. Model studies indicate that the second addition/elimination on OFCP is fast and polycondensation results in linear homopolymers and copolymers without side products. The synthesis of bis(heptafluorocyclopentenyl) aryl ether monomers and their condensation with bisphenols further led to PFCP copolymers with alternating structures. This new class of semifluorinated polymers exhibit surprisingly high crystallinity in some cases and excellent thermal stability.

Fluorinated arylene vinylene ether (FAVE) polymers were prepared from the base-promoted addition of commercial 2,2-bis(4-hydroxyphenyl)hexafluoropropane (6F bisphenol A) to aryl trifluorovinyl ether (TFVE), 2,2′-bis(4-trifluorovinyloxybiphenyl)-1,1,1,3,3,3-hexafluoropropane. The step-growth polymerization kinetics by using stoichiometric NaH and catalytic Cs2CO3 were investigated by monitoring the 19F NMR signals of the aryl TFVEs. The nth order kinetic model was used to determine rate constants over a series of programmed temperatures. Polymerization using stoichiometric NaH resulted in second-order kinetics with an activation energy of 59 kJ/mol. This model kinetic study provided insight into the mechanistic pathways of the FAVE polymer system that has recently shown a lot of interest in many areas of materials science. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011