Reactive and Functional Polymers (v.95, #C)
Editorial Board (IFC).
Enhanced electrokinetic, dielectric and electrorheological properties of covalently bonded nanosphere-TiO2/polypyrrole nanocomposite by Seyda Cabuk; Halil Ibrahim Unal (1-11).
Nanosphere-TiO2 was synthesized, surface functionalized with (3-aminopropyl) triethoxysilane (APTS) and then covalently bonded with polypyrrole (PPy) with bottom-up surface engineering strategy to obtain nanosphere-TiO2/PPy core/shell hybrit nanocomposite. All the materials were subjected to full chemical and morphological characterizations by using various techniques. The presence of NaCl, AlCl3, cetyltrimethyl ammonium bromide and sodium dodecylsulfate observed to cause high colloidal stabilities of the nanocomposite dispersions by reaching to zeta(ζ)-potential values of ζ > + 30 mV and ζ < − 30 mV. A series of suspensions were prepared by dispersing nanosphere-TiO2 and nanosphere-TiO2/PPy particles in insulating silicone oil (SO) and dielectric properties were determined using an LCR meter. Antisedimentation stabilities of these suspensions were determined against gravitational forces and 54% colloidal stability was achieved with the nanocomposite after 30 days. Polarizabilities of the suspended particles were observed using an optical microscope under externally applied electric field strength. Then the suspensions were subjected to electrorheological measurements by investigating the effects of shear rate, particle volume fraction, shear stress, and electric field strength. Non-Newtonian shear thinning behaviors were observed for the samples. Further, vibration damping characteristics of the materials were determined with shear stress and frequency oscillation measurements. Enhanced reversible viscoelastic deformations were observed for the dispersions from creep-recovery tests and 64% creep-recovery was obtained for nanosphere-TiO2/PPy/SO system under E = 3.5 kV/mm.
Keywords: Nanosphere titanium dioxide; Covalent bonding; Electrokinetics; Dielectrics; Electrorheology;
The separation of the pyrethroid insecticide Fastac 10 EC by cationic pullulan derivatives by Luminita Ghimici; Marieta Constantin (12-18).
Pullulan derivatives with different content of tertiary amine groups have been evaluated, as flocculants, for the separation of pesticide Fastac 10 EC from model emulsions. The flocculation performance of the cationic polysaccharide samples at different conditions (Polycation dose, pH and pesticide concentration) was followed by UV–vis spectroscopy measurements. The results show similar values for the maximum removal efficiency (around 90%), irrespective of the ionic groups content and an increase (from 80% to more than 90%) with initial pesticide concentration increase (from 0.02% to 0.04%). The optimum polycation dose decreased with increasing substitution degree and decreasing the emulsion pH. The supernatant zeta potential dependence on the cationic polysaccharide dose indicated a charge neutralization mechanism for the flocculation of pesticide particles, that was supported by particle aggregates size measurements.
Keywords: Pullulan derivative; Fastac 10 EC; Water purification, UV–vis spectroscopy; Zeta potential;
Creation of a new material stream from Japanese cedar resources to cellulose nanofibrils by Zhuqun Shi; Quanling Yang; Yuko Ono; Ryunosuke Funahashi; Tsuguyuki Saito; Akira Isogai (19-24).
Japanese cedar is one of the most abundant plantation softwoods in Japan, although it is not effectively utilized as a wood resource. Japanese cedar cellulose was isolated and subjected to one-pot catalytic oxidation and reduction with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and NaBH4, respectively. The TEMPO-oxidized and NaBH4-reduced Japanese cedar celluloses (TOCs-NaBH4) had carboxylate content of up to 1.4 mmol/g and viscosity-average degrees of polymerization from 2000 to 3000. The X-ray diffraction patterns of the TOCs-NaBH4 showed that the crystal widths were ~ 3 nm, indicating that the C6-OH groups present on the crystalline cellulose microfibril surfaces were selectively oxidized to C6-carboxylate groups. When the TOCs-NaBH4 with carboxylate content of 0.9–1.4 mmol/g were mechanically disintegrated in water, transparent TEMPO-oxidized cellulose nanofibril (TOCN) dispersions were obtained. The lengths of the TOCNs, determined from their atomic force microscopy images, varied from 800 to 1500 nm, depending on the oxidation conditions. The TOCNs prepared from Japanese cedar cellulose have an average of high aspect ratios (> 300), which is greater than that (~ 150) prepared from wood pulp and thus advantageous.Display Omitted
Keywords: Japanese cedar; Cellulose nanofibril; TEMPO-mediated oxidation; Nanofibrillation; Sugar composition;
Polymeric corrosion inhibitors for the oil and gas industry: Design principles and mechanism by Brylee David B. Tiu; Rigoberto C. Advincula (25-45).
This work provides an overview of the most common polymeric corrosion inhibitors for the oil and gas industry. Exploration, production and transportation of petroleum and natural gas products constantly deal with highly corrosive environments due to oxygen, acid stimulation, CO2 and H2S contamination. Therefore, versatile materials are required in order to keep corrosion rates in control. Unlike small molecule corrosion inhibitors, polymers possess multi-functionality and better film-forming capabilities, which could significantly improve protective barrier properties. In this article, polymeric architectures tested in relevant oil and gas media are compiled in order to highlight certain moieties capable of complex formation with the metal surface or chelation on corrosive agents resulting to improved corrosion inhibition.
Keywords: Polymer; Inhibitor; Oil; Gas; Corrosion;
Synthesis and characterization of dual-stimuli-responsive micelles based on poly(N-isopropylacrylamide) and polycarbonate with photocleavable moieties by Jia-You Fang; Yin-Ku Lin; Shiu-Wei Wang; You-Chen Li; Ren-Shen Lee (46-54).
Dual-sensitive block copolymers, PNiPAAm-b-PNBTMC, were synthesized via the ring-opening polymerization of 3-methyl-3-nitrobenzyl-trimethylene carbonate (NBTMC) bearing numerous 2-nitro-benzoxycarbonyl photolabile groups with a PNiPAAm macroinitiator in the presence of an organocatalyst, 1,5,7-triazobicyclo-[4.4.0]dec-5-ene (TBD). When the polymer solutions were exposed to ultraviolet (UV) irradiation, we observed significant changes in the structure and morphology of the particles. Fluorescence spectroscopy studies revealed that the copolymers underwent micellization or dissociation transitions in water in response to temperature changes and UV irradiation. No significant toxicity of these nanoparticles was found at concentrations up to 300 μg mL− 1.
Keywords: Thermo-sensitive; Photocleavable; Poly(N-isopropylamide); Polycarbonate; Micelle;
Cationic polymer chain tethered on the pore-wall of 3-D ordered macroporous resin for the removal of hexavalent chromium from aqueous solution by Xiaomei Wang; Cuihong Wu; Lei Tian; Guohui Li; Xu Zhang; Feng Lei; Jiayan Qu; Pange Liu (55-61).
A novel 3-D ordered macroporous (3DOM) adsorbent with a cationic polymer chain (poly(N,N-dimethylaminoethyl methacrylate), PDMAEMA) tethered on the pore wall was prepared by surface-initiated atom transfer radical polymerization (SI-ATRP) for the removal of toxic Cr(VI) ions from aqueous solution. In comparison with recently reported adsorbents, the adsorbent remarkably stands out owing to large adsorption capacity, relatively fast kinetics, and high stability in the regeneration process. The adsorption capacity significantly depended on the solution pH and there was a wide working pH range that is much convenient in practical application. Kinetics of Cr(VI) adsorption by the 3DOM adsorbent was studied in batch experiments, in the temperature range 298–318 K. The equilibriums were arrived within 120–130 min and a pseudo-second order model can be described well. In the adsorption isotherm study, experimental data followed the Langmuir adsorption model. The maximum adsorption capacity increased with the increase of temperature, and reached the high value of 431.0 mg/g at 308 K. Thermodynamic parameters revealed spontaneous and endothermic adsorption processes. Furthermore, the 3DOM adsorbent remained high adsorption capacity (above 90% of the original Cr(VI) loading capacity) after 15 adsorption–desorption cycles by simply using sodium hydroxide solution as the desorption liquid, which ensured the reusability of 3DOM adsorbent.
Keywords: 3-D ordered macroporous adsorbent; Grafted polymerization; Adsorption; Hexavalent chromium; Reusability;
Effective regeneration of an adsorbent for the removal of organic contaminants developed based on UV radiation and toxicity evaluation by Soonjae Lee; Jae-Sang Lee; Mi-Kyung Song; Jae-Chun Ryu; Byungryul An; Chang-Gu Lee; Chanhyuk Park; Sang-Hyup Lee; Jae-Woo Choi (62-70).
Composites of powdered activated carbon and/or titanium dioxide were investigated as a photo-regenerable adsorbent for use in the removal of 2,4,6-trichlorophenol from aqueous solution. Seven types of adsorbents were prepared for organic contaminant adsorption tests. Lab-scale tests were conducted to investigate the removal efficiencies of 2,4,6-trichlorophenol and the potential for regenerating the adsorbents using UV irradiation. Among these adsorbents, the ultrasonic irradiated alginate bead-impregnated powdered activated carbon and titanium dioxide-dry type 1 (PTAB-D-Sonic 1) exhibited the greatest adsorption capacity for 2,4,6-trichlorophenol (12.38 mg g− 1); in addition, the removal efficiency was consistent approximately 11 mg g− 1, notwithstanding repetitive regeneration by UV irradiation. The characteristics of each adsorbent were confirmed using Brunauer–Emmett–Teller (BET), field-emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray (EDX) analysis. In addition, a cytotoxicity experiment was conducted on the developed material, and the results showed that all seven materials had low cytotoxic effects on human cells. This research provides promising results for the application of a photo-regenerable adsorbent, e.g., PTAB-D-Sonic 1, for the removal of various organic contaminants from sewage and wastewater.
Keywords: Regeneration; Photocatalyst; 2,4,6-Trichlorophenol; Toxicity evaluation; Remote oxidation;
Plasma treatment of the surface of poly(hydroxybutyrate) foil and non-woven fabric and assessment of the biological properties by P. Slepička; Z. Malá; S. Rimpelová; N. Slepičková Kasálková; V. Švorčík (71-79).
This paper deals with the poly(hydroxybutyrate) (PHB, foil and fabric) surface modification, characterization and the view of its possible application. The influence of Ar plasma treatment on surface polarity was studied. The changes of the surface parameters were determined immediately after treatment and after annealing related to plasma power, treatment time and heating. These surface-induced differences were studied by different analytic methods: polarity (wettability) was studied by contact angle measurement and surface energy calculation, the surface morphology analysis was done by atomic force microscopy and for determination of chemical composition of surface layer the XPS analysis was used. It was found that after plasma treatment the surface energy of both PHB foil and non-woven fabric significantly increased. PHB non-woven fabric exhibited almost immeasurable contact angle after the plasma treatment. The wettability of both types of PHB substrates after heating was completely inversed. The significant change in roughness of PHB foil was found. After the plasma treatment, the material ablation was determined, which was also connected with surface chemical changes, thus the surface was found to be corrugated. The heating procedure induced “little” crystallites on the surface. Positive effect of PHB foil modifications on surface biocompatibility was confirmed. The biocompatibility was also preserved when thermal stress was applied. Silver nanolayer sputtered on PHB fabric surface induced strong anti-microbial properties.
Keywords: Biopolymers; Functionalization; Plasma treatment; Nanostructuring; Biological properties;
Effect of HNTs modification in nanocomposite membrane enhancement for bacterial removal by cross-flow ultrafiltration system by A. Moslehyani; M. Mobaraki; A.F. Ismail; T. Matsuura; S.A. Hashemifard; M.H.D. Othman; A. Mayahi; M. Rezaei DashtArzhandi; M. Soheilmoghaddam; E. Shamsaei (80-87).
This study investigated the potential of silver lactate (SL)-holloysite nanotube clay (HNTs) nano-filler embedded into the polyvinylidene fluoride (PVDF) polymer matrix as an antibacterial separator. Three different nanocomposite membranes were fabricated via phase inversion technique aimed to enhance the permeation flux and fouling resistance with complete bacterial rejection. HNT has been modified by N-β-(aminoethyl)-ɣ-aminopropyltrimethoxy silane (AEAPTMS) aiming for immobilization of SL on the surface HNT during dope preparation. Salmonella and Enterobacter aerogenes (E. aerogenes) were considered as two types of bacteria to be removed from contaminated water in this experimental work. Nanocomposite membranes were characterized and analyzed by thermal gravimetric analysis (TGA), Fourier transform infrared (FTIR), field emission scanning electron microscopy (FESEM) combined with energy dispersive X-ray (EDX), X-ray photoelectron spectroscope (XPS), atomic force microscopy (AFM), contact angle, molecular weight cut-off (MWCO) and tensile strength. Potential silver ion loss was assessed by measuring the silver content in the coagulation bath and in the UF permeate using inductive-coupled plasma mass spectrometer (ICP-MS). Moreover, antibacterial effect of the membrane was examined in terms of removal of microorganisms by filtration, Log Reduction Value (LRV) and thickness of inhibition zone. From the experimental results, the prepared nanocomposite membranes have shown more than 99% bacterial rejection, LRV of more than 3 and broad inhibition zones in the agar plate. In particular, the nanocomposite membrane consisting M-HNTs/SL/PVDF showed significant improvement in permeation flux and flux declination among all the tested membranes. It was also found that modification of HNTs resulted in reduction of silver leaching by uniform distributing of SL, which contributed to significant inhibition for both types of growth bacteria within 24 h of incubation.
Keywords: Nanocomposite; Membrane; UF; SL; HNTs; PVDF; Antibacterial;