Fabrication of High-Performance Flexible Supercapacitor Electrodes with Poly(3,4-ethylenedioxythiophene) (PEDOT) Grown on Carbon-Deposited Polyurethane Sponge

Composite porous supercapacitor electrodes were prepared by growing poly(3,4-ethylenedioxythiophene) (PEDOT) on graphite nanoplatelet- or graphene nanoplatelet-deposited open-cell polyurethane (PU) sponges via a vapor phase polymerization (VPP) method. The resulting composite supercapacitor electrodes exhibited great capacitive performance, with PEDOT acting as both the conductive binder and the active material. The chemical composition was characterized by Raman spectroscopy and the surface morphology was characterized by scanning electron microscopy (SEM). Cyclic voltammetry (CV), charge-discharge (CD) tests and electrochemical impedance spectroscopy were utilized to study the electrical performance of the composite electrodes produced in symmetrically configured supercapacitor cells. The carbon material deposited on PU substrates and the polymerization temperature of PEDOT affected significantly the PEDOT morphology and the electrical properties of the resulting composite sponges. The highest areal specific capacitance 798.2 mF cm−2 was obtained with the composite sponge fabricated by VPP of PEDOT at 110 °C with graphene nanoplatelet-deposited PU sponge substrate. The capacitance retention of this composite electrode was 101.0% after 10,000 charging–discharging cycles. The high flexibility, high areal specific capacitance, excellent long-term cycling stability and low cost make these composite sponges promising electrode materials for supercapacitors.

The Effect of Polymerization Temperature on the Properties of Polyvinyl Fluoride Polymerization in Supercritical Carbon Dioxide

The ongoing search for environmentally friendlier alternative to the organic solvents used in chemical processes has led to the development of technologies based on supercritical carbon dioxide (scCO2), which is non-flammable, non-toxic and relatively inert fluid. Polymer chemistry does not escape this trend. Fluoropolymers prepared in scCO2 have many special properties, which are different from fluoropolymers that use water as the reaction medium, this paper studies the effect of polymerization temperature on polyvinyl fluoride polymerization in supercritical carbon dioxide. The results show that as the polymerization temperature increases, the intrinsic viscosity and shear viscosity of the polymer gradually decreases; at the same time, the increasing of polymerization temperature leads to higher proportion of irregular structure of the polymer, which causes lower melting point and lower crystallinity, and the film prepared by the resin also exhibits a higher visible light transmittance. The above results show that the resin polymerized in supercritical carbon dioxide can impart better performance to conventional polymerization, which expands the potential application fields of the resin.

Polymerization of Isobutylene in a Rotating Packed Bed Reactor: Experimental and Modeling Studies

Polymerization of isobutylene (IB) for synthesizing highly reactive polyisobutylene (HRPIB) is characterized by a complicated fast intrinsic reaction rate; therefore, the features of its products exhibit a strong dependence on mixing efficiency. To provide uniform and efficient mixing, a rotating packed bed was employed as a reactor for polymerization of IB. The effects of operating parameters including polymerization temperature (T), rotating speed (N) and relative dosage of monomers and initiating systems ([M]0/[I]0) on number-average molecular weight (Mn) of HRPIB were studied. HRPIB with Mn of 2550 g·mol−1 and exo-olefin terminal content of 85 mol% were efficiently obtained at suitable conditions as T of 283 K, N of 1600 rpm and [M]0/[I]0 of 49. Moreover, the Mn can be regulated by changing T, N and [M]0/[I]0. Based on the presumptive-steady-state analysis method and the coalescence–redispersion model, a model for prediction of the Mn was developed and validated, and the calculated Mn values agreed well with experimental results, with a deviation of ±10%. The results demonstrate that RPB is a promising reactor for synthesizing HRPIB, and the given model for Mn can be applied for the design of RPB and process optimization.

Outcomes of Patients Treated With Antibiotic-Loaded Acryl Bone Cement For Periprosthetic Hip Infection, Stratified By Cement Polymerization Temperature: A Retrospective Study

Background: Two-stage revision surgery using antibiotic-loaded acryl bone cement (ALAC) is an effective treatment for periprosthetic joint infection (PJI) after hip arthroplasty. However, ALAC has been reported to release different amounts of antibacterial agents, depending on the type of bone cement used. No previous study has examined patient outcomes based on the polymerization temperature of the bone cement used. This study aimed to compare the outcomes of patients who underwent a two-stage revision surgery using ALAC for PJI, stratified by the polymerization temperature of the bone cement used.Methods: This study involved 23 joints in 23 patients treated with ALAC between 1993 and 2019. They were classified into normal (control group, n=12) and low polymerization temperature (L group, n=11) groups, respectively. Patient outcomes were compared between the groups.Results: In both groups, the infection subsiding rate was 100%. The success rate of revision surgery at the 2-year follow-up was 82.6%. There was no difference between the groups in mean age, time to infection onset, patient general condition, presence of fistulas, or methicillin-resistant Staphylococcus aureus infection. However, the infection required less time to subside, and fewer beads or spacers were used in the L group than in the control group. The success rate of revision surgery was 66.7% and 100% in the control and L groups, respectively.Conclusions: In the present study, two-stage revision surgery with ALAC in PJI was associated with a shorter infection subsidence period and fewer surgeries in the group treated with bone cement of low polymerization temperature than in the control group. The use of bone cement of low polymerization temperature in ALAC is an effective treatment option for PJI.

Sodium Polyacrylate as a Super Absorbent

This work is devoted to the study of synthesis, properties and practical Applications of class of acrylic-based sodium Polyacrylate superabsorbent polymers. The techniques of solution, emulsion/gel polymerization were used for synthesis. Each absorbent was mainly characterized by its equilibrium capacity of water absorption and by the rate of absorption. The swelling characteristics of the polymers were evaluated in terms of change in polymerization variables which include, type and amount of cross linker, monomer composition, and process of polymerization, temperature, initiator concentration, monomer concentration, Rate of agitation and particle size of the product. The swelling dependency on salinity, ionic strength and PH was also examined. The rapid growing nanotechnology has led to more explorations of SAPs and SAPCs for applications in biomedical, biotechnology and advanced technologies. Examples of research work of SAPs and SAPCs published in refereed, reviewed articles are referred.

Hafnium vs. Zirconium, the Perpetual Battle for Supremacy in Catalytic Olefin Polymerization: A Simple Matter of Electrophilicity?

The performance of C2-symmetric ansa-hafnocene catalysts for isotactic polypropylene typically deteriorates at increasing temperature much faster than that of their zirconium analogues. Herein, we analyze in detail a set of five Hf/Zr metallocene pairs—including some of the latest generation catalysts—at medium- to high-polymerization temperature. Quantitative structure–activity relationship (QSAR) models for stereoselectivity, the ratio allyl/vinyl chain ends, and 2,1/3,1 misinsertions in the polymer indicate a strong dependence of polymerization performance on electrophilicity of the catalyst, which is a function of the ligand framework and the metal center. Based on this insight, the stronger performance decline of hafnocenes is ascribed to electrophilicity-dependent stabilization effects.

Inkjet Printing of Polypyrrole Electroconductive Layers Based on Direct Inks Freezing and Their Use in Textile Solid-State Supercapacitors

In this work, we propose a novel method for the preparation of polypyrrole (PPy) layers on textile fabrics using a reactive inkjet printing technique with direct freezing of inks under varying temperature up to −16 °C. It was found that the surface resistance of PPy layers on polypropylene (PP) fabric, used as a standard support, linearly decreased from 6335 Ω/sq. to 792 Ω/sq. with the decrease of polymerization temperature from 23 °C to 0 °C. The lowest surface resistance (584 Ω/sq.) of PPy layer was obtained at −12 °C. The spectroscopic studies showed that the degree of the PPy oxidation as well as its conformation is practically independent of the polymerization temperature. Thus, observed tendences in electrical conductivity were assigned to change in PPy layer morphology, as it is significantly influenced by the reaction temperature: the lower the polymerization temperature the smoother the surface of PPy layer. The as-coated PPy layers on PP textile substrates were further assembled as the electrodes in symmetric all-solid-state supercapacitor devices to access their electrochemical performance. The electrochemical results demonstrate that the symmetric supercapacitor device made with the PPy prepared at −12 °C, showed the highest specific capacitance of 72.3 F/g at a current density of 0.6 A/g, and delivers an energy density of 6.12 Wh/kg with a corresponding power density of 139 W/kg.

Red Mud-Based Polyaluminum Ferric Chloride Flocculant: Preparation, Characterization and Flocculation Performance

In this work, red mud was used as raw material to extract Al and Fe with hydrochloric acid. The high-efficiency polyaluminum iron chloride (PAFC) flocculant was prepared via adjusting the pH of the leaching solution, the molar ratio of aluminum and iron, and the polymerization temperature. The effect of synthesis and flocculation conditions on the flocculation performance of aged landfill leachate was investigated. The results confirmed that the PAFC prepared at the polymerization pH of 2.5, the Al/Fe molar ratio of 8, and the polymerization temperature of 70 °C had the optimum flocculation effect. The flocculation consequences of PAFC and commercial polyaluminum iron chloride flocculant (CPAFC) under different flocculation conditions were compared. The chemical oxygen demand (COD), UV254, chroma and settlement height of PAFC at flocculant concentration of 60 g/L and solution pH of 6 were 72.2%, 79.2%, 82.9% and 9.5 cm (within 90 min), respectively. PAFC has excellent flocculation performance and can be used as a simple, potentially low-cost wastewater treatment agent in industrial applications.

Ring opening polymerization of ε-caprolactone initiated by titanium and vanadium complexes of ONO-type schiff base ligand

A phenoxy-imine proligand with the additional OH donor group, 4,6-tBu2-2-(2-CH2(OH)-C6H4N = CH)C6H3OH (LH2), was synthesized and used to prepare group 4 and 5 complexes by reacting with Ti(OiPr)4 (LTi) and VO(OiPr)3 (LV). All new compounds were characterized by the FTIR, 1H and 13C NMR spectroscopy and LTi by the single-crystal X-ray diffraction analysis. The complexes were used as catalysts in the ring opening polymerization of ε-caprolactone. The influence of monomer/transition metal molar ratio, reaction time, polymerization temperature as well as complex type was investigated in detail. The complexes showed high (LTi) and moderate (LV) activity in ε-caprolactone polymerization and the resultant polycaprolactones exhibited Mn and Mw/Mn values ranging from 4.0 · 103 to 18.7 · 103 g/mol and from 1.4 to 2.5, respectively.

Propargylamine: An Attractive Amino Source for Designing High-Performance Benzoxazine Resins with Low Polymerization Temperatures

Aniline is a very common amino source for benzoxazine synthesis, but generally resulting in relatively high ring-opening polymerization temperatures. The exploration of alternative amine sources to lower the polymerization temperature...