Reactive and Functional Polymers (v.93, #C)
Editorial Board (IFC).
Synthesis and evaluation of different adsorbents based on poly(methacrylic acid–trimethylolpropane trimethacrylate) and poly(vinylimidazole–trimethylolpropane trimethacrylate) for the adsorption of tebuthiuron from aqueous medium by Raquel Justo da Fonseca; Mariana Gava Segatelli; Keyller Bastos Borges; César Ricardo Teixeira Tarley (1-9).
In the present study a new cross-linked copolymer poly(methacrylic acid–trimethylolpropane trimethacrylate) (named PMA) and poly(vinylimidazole–trimethylolpropane trimethacrylate) (named PVI) was synthesized through precipitation polymerization and applied to the adsorption of tebuthiuron. Adsorbent materials were characterized by using FT-IR, SEM, TGA, textural data, and elemental analysis. Kinetic study showed that the tebuthiuron adsorption was very quick and the equilibrium time was achieved at 20 min for both polymers. Experimental kinetic data for both polymers were very well described by the second-order kinetic model, thus indicating that tebuthiuron adsorption involves chemical adsorption in different binding sites, which could control the reaction rate. Adsorption equilibrium data were better fitted to the dual-site Langmuir–Freundlich model, which recognizes the existence of two kinds of adsorption sites on the polymer surface ascribed to the presence of carboxyl and carbonyl groups from PMA and imidazole ring and carbonyl group from PVI. The maximum adsorption capacities of PMA and PVI were found to be 186.76 and 213.89 mg g− 1, respectively, which are much higher than other adsorbents.
Keywords: Herbicide; Isotherm; Kinetic; Organic polymer; HPLC;
Optically active, magnetic microspheres: Constructed by helical substituted polyacetylene with pendent prolineamide groups and applied as catalyst for Aldol reaction by Jiexuan Song; Haiyang Zhang; Jianping Deng (10-17).
This article reports on the preparation of a novel category of optically active magnetic microspheres (OAMMPs) consisting of Fe3O4 nanoparticles and helical substituted polyacetylene bearing pendent prolineamide groups and the use of them for asymmetric direct Aldol reactions. The microspheres (200–300 μm in diameter) were prepared by using chiral acetylenic monomer and alkynyl-Fe3O4 nanoparticles via suspension polymerization approach. They were obtained in high yield (> 99%) with regular spheric morphology and exhibited noticeable optical activity, according to circular dichroism spectra and specific optical rotation measurements. The microspheres further served as chiral catalyst for performing direct Aldol reactions between acetone and p-nitrobenzaldehyde, providing the product in moderate yield (68%) and ee (75%). The magnetic microspheres can be easily recycled and reused. Mechanism for the asymmetric catalysis of Aldol reaction was further proposed.
Keywords: Helical polymers; Optically active microspheres; Fe3O4 nanoparticles; Asymmetric catalysis; Aldol reaction;
Synthesis of water-soluble wholly aromatic polyketones bearing 1,1′-binaphthyl-6,6′-diyl units by Katsuya Maeyama; Hiroaki Kumagai (18-21).
A water-soluble wholly aromatic polyketone modified with sodium carboxylate (PK-COONa) was synthesized through demethylation of the wholly aromatic polyketone bearing four methoxy groups per repeat unit (PK-OMe) followed by ethoxycarbonylmethylation and saponification. The obtained polyketones, i.e., the methyl-cleaved analogue (PK-OH), the ethoxy carbonyl group-bearing analogue (PK-COOEt), the sodium carboxylate analogue (PK-COONa), and the carboxy group-bearing analogue (PK-COOH), have varying solubilities in water and common organic solvents and thermal stabilities, depending on the functional groups.Display Omitted
Keywords: Wholly aromatic polyketone; Water-soluble; Macromolecular reaction;
Studies on uptake behavior of Hg(II) and Pb(II) by amine modified glycidyl methacrylate–styrene–N,N′-methylenebisacrylamide terpolymer by Archana Gupta; Rajeev Jain; D.C. Gupta (22-29).
The removal of mercury and lead ions from aqueous solutions investigated by ethylenediamine, diethylenetriamine and tetraethylenepentamine functionalized polymeric adsorbent. The adsorbent was prepared by amination of terpolymer synthesized from glycidylmethacrylate, styrene and N,N′-methylenebisacrylamide. In the single metal species system (only mercury or lead ions are present) poly(glycidylmethacrylate–ethylenediamine) (PGMA–EDA), poly(glycidylmethacrylate–diethylenetriamine) (PGMA–DETA), and poly(glycidylmethacrylate–tetraethylenepentamine) (PGMA–TEPA) were found to adsorb lead or mercury ions with a slightly higher adsorption uptake capacity for lead than mercury ions. Among the three functionalized polymers poly(glycidylmethacrylate–diethylenetriamine) (PGMA–DETA) shows faster and higher adsorption capacity than poly(glycidylmethacrylate–ethylenediamine) (PGMA–EDA), poly(glycidylmethacrylate–tetraethylenepentamine) (PGMA–TEPA). The natural pH of both the metal ions was found to be most suitable for uptake. The uptake of Hg(II) and Pb(II) ions was investigated by using batch technique. The maximum adsorption capacities of Pb ions were predicted to be 4.74, 4.76 and 4.73 mmol/g and the maximum Hg(II) ion uptakes were found to be 4.76, 4.80 and 4.21 mmol/g respectively for PGMA–EDA, PGMA–DETA and PGMA–TEPA resins at their natural pH. The uptakes of Hg(II) and Pb(II) ions on the resins were found to follow Langmuir adsorption isotherm and pseudosecond order kinetics.
Keywords: Suspension polymerization; Amine functionalized resins; Mercury and lead ion removal; Adsorption isotherm; Kinetics study;
Preparation and characterization of antimicrobial electrospun poly(vinyl alcohol) nanofibers containing benzyl triethylammonium chloride by Jeong-Ann Park; Song-Bae Kim (30-37).
The aim of this study was to characterize antimicrobial electrospun poly(vinyl alcohol) (PVA) nanofibers containing benzyl triethylammonium chloride (BTEAC) as an antimicrobial agent. The antimicrobial BTEAC-PVA nanofibers were prepared through electrospinning at the optimal conditions of 15 kV voltage and a 1.0 mL h− 1 flow rate. Based on the minimum inhibitory concentration (MIC) test results against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli and Klebsiella pneumonia, BTEAC-PVA nanofibers containing 2.6% BTEAC were fabricated to test the antibacterial and antiviral activities. The average diameter of the BTEAC-PVA nanofibers increased from 175.7 to 464.7 nm with increasing BTEAC concentration from 0 to 2.6%. The antimicrobial activities of the BTEAC-PVA nanofibers were tested against bacteria. The antibacterial tests with 2.6% BTEAC-PVA nanofibers demonstrated that bacterial reduction in PVA nanofibers was similar to the control value, indicating that PVA had a minimal effect on bacteria death. For the BTEAC-PVA nanofibers, the bacterial reduction ratio increased with increasing contact time, demonstrating that BTEAC-PVA nanofibers successfully inhibited the growth of bacteria. In addition, the antiviral tests against viruses (bacteriophages MS2 and PhiX174) showed that the BTEAC-PVA nanofibers inactivated both MS2 and PhiX174.
Keywords: Antimicrobial agent; Antimicrobial nanofiber; Benzyl triethylammonium chloride; Electrospinning; Poly(vinyl alcohol);
Facile method towards functionalization of partially fluorinated polyarylethers via sequential post-polymerization modification by Jingbo Wu; Jau-Hung Liou; Charles Y. Shu; Yash Patel; Remya Menon; Cara Santucci; Scott T. Iacono; Dennis W. Smith; Bruce M. Novak (38-46).
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.
Keywords: Fluoropolymers; Post-functionalization; Polymer synthesis; Thermoplastic; Advanced materials;
Synthesis and characterization of poly(lactic acid) based graft copolymers by Tungabidya Maharana; Sasmita Pattanaik; Anita Routaray; Nibedita Nath; Alekha Kumar Sutar (47-67).
This review summarizes recent developments in the preparation and characterization of grafting of poly(lactic acid) or polylactide (PLA). PLA is the most expansively researched and utilized biodegradable, biocompatible, compostable, recyclable and renewable thermoplastic polyester. The graft copolymers of PLA have been synthesized and characterized by different spectroscopic techniques, including FTIR spectra and NMR data. The graft copolymers of PLA have been analyzed critically by taking different monomers/polymers; such as chitosan, cellulose, starch, polyethylene glycol, vinyl based polymers, lignin, dextran, methyl methacrylate, maleic anhydride and graphene oxide. In the first part of this review, the grafting of PLA and applications of grafted PLA has been discussed briefly. The second part, the major objective of this paper, focuses on the synthesis and characterization of different PLA based graft copolymers. For few cases, where useful properties, such as high molecular weight, narrow PDI, or stereocontrol, have been observed, a more detailed examination of the graft copolymers is provided.
Keywords: Polymerization; Grafting; Poly(lactic acid); Chitosan; Cellulose;
pH-responsive superabsorbent polymers: A pathway to self-healing of mortar by Arn Mignon; Didier Snoeck; David Schaubroeck; Nathalie Luickx; Peter Dubruel; Sandra Van Vlierberghe; Nele De Belie (68-76).
Cracks are concrete's worst problem. External, passive treatments are expensive and time consuming. pH-responsive superabsorbent polymers (SAPs) offer an internal active solution. When cracks occur, the SAPs can swell, fill the crack (self-sealing) and assist in the formation of healing products (self-healing). In previous work, a range of (superabsorbent) polymers have been synthesized and characterized. Based on these results, the two best performing SAPs were chosen for further characterization. The results indicate that the SAPs developed do not show degradation in cement filtrate solutions. Upon addition of SAPs, a decrease in mortar strength occurred, yet a positive effect on self-sealing was observed since the water permeability decreased. Furthermore, the formation of products became apparent at the sealed cracks of the mortar samples containing 1 m% SAPs. Identification using scanning electron microscopy, infrared spectroscopy and thermogravimetric analysis indicated that the products mainly consisted of healing products (more specifically CaCO3) which is illustrative for self-healing.
Keywords: Superabsorbent polymer; Self-sealing; Self-healing; Water permeability; Compression strength;
Tyramine modified alginates via periodate oxidation for peroxidase induced hydrogel formation and immobilization by Olivera Prodanovic; Dragica Spasojevic; Milos Prokopijevic; Ksenija Radotic; Nevena Markovic; Marija Blazic; Radivoje Prodanovic (77-83).
Phenol and amino groups were introduced into alginate to different degrees via oxidation with 2.5, 5, 10, 15 and 20 mol% of periodate and reductive amination by tyramine. Modification of alginate with tyramine was confirmed by FTIR spectroscopy and UV–VIS spectroscopy, while concentration of phenol and ionizable groups was determined using absorbance at 275 nm and acid–base titration. All tyramine-alginates were able to form hydrogels after cross-linking with horse radish peroxidase (HRP) and hydrogen peroxide. Tyramine-alginates oxidized with up to 10 mol% of periodate were also capable of forming hydrogels with calcium ions. Tyramine-alginates were tested for HRP immobilization within micro-beads obtained by peroxidase catalyzed droplet polymerization using internal delivery of hydrogen peroxide via glucose oxidase and glucose. Highest activity of immobilized peroxidase was obtained with 20% (w/v) tyramine-alginate obtained via 20 mol% periodate oxidation. Immobilized enzyme was not leaking from the micro-beads and was further kinetically characterized for pyrogallol oxidation. Km for pyrogallol was increased after immobilization from 1.93 mM for soluble HRP to 7.34 mM for immobilized HRP. The optimum pH was also increased from pH 7.0 to 8.0. Temperature and organic solvent stability improved significantly after immobilization, so that half-life at 70 °C increased around four times, while half-life in 80% (v/v) dioxane increased 22 times. After repeated use of 6 times in batch reactor for pyrogallol oxidation immobilized HRP retained 45% of original activity.
Keywords: Hydrogel; Tyramine; Polymerization; Emulsion; Peroxide;
Polymeric anion exchanger supported hydrated Zr(IV) oxide nanoparticles: A reusable hybrid sorbent for selective trace arsenic removal by Surapol Padungthon; Michael German; Surases Wiriyathamcharoen; Arup K. SenGupta (84-94).
Natural groundwater contamination by arsenic puts over 100 million people at-risk throughout the world. If arsenic is the primary concern, the most ideal treatment solution would be a regenerable fixed-bed adsorbent: minimal energy requirement, simple operation and low cost. Such an adsorbent should have high arsenic capacity, high physical/chemical durability and high regenerability for several cycles of reuse. Hybrid anion exchange resins impregnated with hydrous zirconium oxide nanoparticles (HAIX–Zr) combine the physical durability and high anion diffusivity of anion exchanger resins with the high arsenic capacity and high chemical durability of zirconium oxides. HAIX–Zr was synthesized using non-hazardous and easy-to-transport pre-calcined zirconium oxide and was tested to be an effective As(V) and As(III) adsorbent over several cycles of exhaustion–regeneration in the presence of high concentrations of competing anions; at high concentrations, phosphate and silica show competition with arsenic. The high regenerability of HAIX–Zr (> 90%) makes it more sustainable to regenerate and reuse the HAIX–Zr for numerous cycles to reduce the volume of arsenic-laden waste. Unlike other iron- or aluminum-based adsorbents, HAIX–Zr is chemically stable at landfill conditions where it could be safely disposed without leaching arsenic.
Keywords: Arsenic; Zirconium oxide; Nanoparticles; Adsorption; Hybrid ion exchange resins;
Renewable epoxy networks by photoinitiated copolymerization of poly(3-hydroxyalkanoate)s and isosorbide derivatives by C. Lorenzini; D.L. Versace; E. Renard; V. Langlois (95-100).
New biodegradable epoxy networks derived from poly(3-hydroxyalkanoate)s and isosorbide were synthesized by photoinitiated cationic ring opening polymerization in the presence of diaryl iodonium salt (I 250). Bis-epoxidized terminated PHA oligomers, PHA-diepoxy, were first prepared in three steps, microwave assisted alcoholysis in the presence of ethylene glycol, condensation with allyl isocyanate and epoxidation of alkene terminal groups. Moreover, isosorbide diglycidyl ether (DGEDAS) was prepared by epoxidation of allylic derivative. The photoinitiated polymerization is a straightforward way applied at room temperature in a very short reaction time (i.e. 300 s) to obtain renewable crosslinked networks that remain partially biodegradable by lipase. Higher degradability was observed by increasing the content of PHA.
Keywords: Poly(3-hydroxyalkanoate)s; Biopolyesters; Isosorbide; Epoxy network; Photochemistry;
New fluorescent hyperbranched polymeric sensors as probes for monitoring photopolymerization reactions by Sandra Medel; Paula Bosch (101-110).
Two polychromophoric dansyl hyperbranched fluorescent probes (HBPs) have been used as fluorescent sensors to follow photopolymerization reactions of acrylic monomers through fluorescence monitoring. Simultaneously, photo-DSC measurements were conducted. The combined data obtained by both techniques allowed to measure precise and adequately the kinetics of the systems. Differences are found depending on the composition of the formulation, but no depending on the probe inserted in the systems. The behavior and sensitivity of the functional HBP's have been compared with their low molecular weight monochromophoric reference compounds. Hyperbranched polychromophoric probes showed the same sensitivity towards the process than the monochromophoric probes, confirming the high sensitivity of the hyperbranched probes. Also, the data obtained by fluorescence allow distinguishing the different steps involved in the mechanism of a radical crosslinking polymerization, which could not be observed only with calorimetric measurements. The advantages of the functional HBP fluorescent probes towards their low molecular weight homologues are discussed.Display Omitted
Keywords: Hyperbranched polymers; Photopolymerization kinetics; Fluorescent sensors; Photopolymerization mechanism;
An investigation on the effect of phenylboronic acid on the processibilities and thermal properties of bis-benzoxazine resins by Shujuan Wang; Qinxiang Jia; Yuhong Liu; Xinli Jing (111-119).
Benzoxazine resins (BZs) as a novel type of phenolic resin are high-performance matrix resin for advanced composites. Yet there still exist some deficiencies when used as ablative material in aerospace applications, such as high curing temperature and poor thermal stability. In the present study, the phenylboronic acid (PBA) modified BZs (PBBZs) exhibiting excellent processibilities and thermal properties were prepared by incorporating PBA into BZ. The viscosity, gel time and curing behaviors were examined to demonstrate that PBBZs possessed better processibilities than the BZ, representing the catalytic effect of PBA in this case. The incorporation of PBA accelerated the ring-opening polymerization of BZ, leading to the lower curing temperature. TGA results reveal that the cured PBBZs exhibit excellent thermal properties, where the char yield at 800 °C (nitrogen atmosphere) reaches 63.7% and is increased by 14.1 percentage points than that of BZ. The formed phenylboronates during curing act as additional cross-linking points and increase the cross-linking density of the cured resin, which results in the enhancement of the glass transition temperature of BZ ranging from 165 °C to 219 °C. This study provides a new vision for the preparation of high-performance matrix resin for ablative materials by introducing aryl-boron backbone.Display Omitted
Keywords: Benzoxazine resin; Thermal property; Char yield; Processibility; Phenylboronate;
Aspartic acid in a new role: Synthesis and application of a pH-responsive cyclopolymer containing residues of the amino acid by Zakariyah A. Jamiu; Hasan A. Al-Muallem; Shaikh A. Ali (120-129).
The reaction between diallylamine and dimethyl maleate afforded the Michael addition product dimethyl N,N-diallylaspartate [(CH2 ＝CH–CH2)2NCH(CO2Me)CH2CO2Me] I , which upon treatment with dry HCl and ester hydrolysis with aqueous HCl gave its hydrochloride salt [(CH2 ＝CH–CH2)2NH+CH(CO2Me)CH2CO2Me Cl−] II and N,N-diallylaspartic acid hydrochloride [(CH2 ＝CH–CH2)2NH+CH(CO2H)CH2CO2H Cl−] III, respectively. The new monomers II and III underwent cyclopolymerization to give, respectively, cationic polyelectrolytes (CPEs) poly(II ) and poly(III). Under the influence of pH, triprotic acid (+) poly(III) was equilibrated to water-insoluble diprotic polyzwitterionic acid (±) IV, water-soluble monoprotic poly(zwitterion–anion) (± −) V, and its conjugate base polydianion (=) VI. The protonation constants of the carboxyl group and trivalent nitrogen in VI have been determined. A 20-ppm concentration of IV is effective in inhibiting the precipitation of CaSO4 from its supersaturated solution with an ≈ 100% scale inhibition efficiency for a duration of 50 h at 40 °C. The aqueous two-phase systems (ATPSs) of VI and polyoxyethylene have been studied. The transformation of water-soluble VI to insoluble IV makes it a recycling ATPS as it can be recycled by precipitation at a lower pH.
Keywords: pH-responsive polymers; Cyclopolymerization; Aqueous two-phase system; Aspartic acid; Phase diagram;
Synthesis and chemosensory properties of terpyridine-containing diblock polycarbazole through RAFT polymerization by Ruey-Shin Juang; Po-Chih Yang; Hua-Wen Wen; Cheng-Yi Lin; Sih-Ciao Lee; Ting-Wei Chang (130-137).
This paper describes the synthesis of a terpyridine-containing diblock copolymer, poly(N-vinylcarbazole)-block-poly[4′-((4-vinylphenyl) phenyl)-2,2′:6′,2″- terpyridine] (poly(VK15-b-TPY4)), using the macro-chain transfer agent VK macro-CTA, and employing two-step reverse addition-fragmentation transfer (RAFT) polymerization. We examined the effect of terpyridine units on sensory characteristics of fluorescent chemosensors. VK macro-CTA and diblock copolymer poly(VK15-b-TPY4) both exhibited moderate thermal stability, with thermal decomposition temperatures of 5% weight losses at approximately 307 °C and 378 °C, respectively, suggesting that the enhancement of thermal stability was attributed to the incorporation of terpyridine segments into the block copolymer. Poly(VK15-b-TPY4) exhibited higher sensitivities to Ni2 + and Mn2 + ions, with Stern–Volmer constants (K sv) of 2.58 × 105 M− 1 and 2.57 × 105 M− 1, respectively. Adding a Zn2 + ion not only caused partial fluorescence enhancement (3.2-fold quantum efficiency) but also induced a bathochromic shift of emission peak by approximately 56 nm (from 429 nm to 485 nm), indicating that the Zn2 +-terpyridine complex reduced the twist and vibration of the C–C polymer backbone and enhanced the charge transfer from donors to acceptors because of the more planar and rigid structure. Our results suggest that poly(VK15-b-TPY4) is a promising material for chemosensory applications.
Keywords: Diblock copolymer; Chemosensor; Terpyridine; Reversible-fragmentation chain transfer polymerization (RAFT);
Applicability and toxicity evaluation of an adsorbent based on jujube for the removal of toxic heavy metals by Byungryul An; Chang-Gu Lee; Mi-Kyung Song; Jae-Chun Ryu; Soonjae Lee; Seong-Jik Park; Dongye Zhao; Song-Bae Kim; Chanhyuk Park; Sang-Hyup Lee; Seok Won Hong; Jae-Woo Choi (138-147).
The removal of heavy metals from industrial wastewater is important, owing to its eco-toxicity in aqueous environment. In this study, the mechanism and efficiency of the removal of toxic heavy metals by an eco-friendly adsorbent was investigated. Various types of adsorbents made from jujube were synthesized by varying the drying temperature of gel-type beads and elution method for jujube constituents. The maximum adsorption capacity for lead and copper ions was determined using the Langmuir isotherm model, with DJB-A-S-F (freeze-dried jujube bead made from a solution of squeezed autoclaved jujube) having the highest values at 60.44 mg/g (lead) and 20.33 mg/g (copper). In addition, the characteristics of the various adsorbents were determined by the Brunauer–Emmett–Teller (BET) method, scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDX). Gas chromatography–mass spectrometry (GC–MS) was used to identify the constituents of DJB-A-S-F before and after adsorption of heavy metals (Pb- and Cu-DJB-A-S-F). Furthermore, in vitro cytotoxicity assay was performed to investigate whether the binding of heavy metals to DJB-A-S-F increases cellular toxicity. As a result, no differences in cell viability between DJB-A-S-F and the ones coupled to heavy metals were observed, indicating that the developed adsorbents are non-cytotoxic with good compatibility. Thus, DJB-A-S-F is a promising adsorbent for the removal of toxic heavy metal cations from wastewater.
Keywords: Eco-friendly; Toxic heavy metals; Adsorption; Jujube; Toxicity evaluation;
Dynamic covalent cross-linked polymer gels through the reaction between side-chain β-keto ester and primary amine groups by Binoy Maiti; Bhuban Ruidas; Priyadarsi De (148-155).
A dynamic covalent gel network was constructed via the coupling reaction between the pendant primary amine groups of poly(l-leucine methacryloyloxyethyl ester) (P(H2N-Leu-EMA)) and the side-chain β-keto ester functionalities of poly(2-(acetoacetoxy)ethyl methacrylate) (PAEMA) by varying the molar ratios of P(H2N-Leu-EMA)/PAEMA and the concentration of polymers in different solvents at room temperature. Fourier transform infrared (FT-IR) spectroscopy and solid-state 13C nuclear magnetic resonance (NMR) study confirmed the newly formed enamine bonds in the polymeric gel. Rheological studies showed that the mechanical strength of gels increased with increasing weight percentage (wt.%) of polymers in solution. Furthermore, polymer gels can be transferred to the mixture of starting polymer solutions by regulating the pH of the system, which can be further transformed into the gel state by adding an external base.Display Omitted
Keywords: Coupling reaction; Amino-acid-containing polymer; β-Keto ester functionality; Polymeric gel; Storage modulus;
Photoprotective effect of starch/montmorillonite composites on ultraviolet-induced degradation of herbicides by Amanda S. Giroto; Adriana de Campos; Elaine I. Pereira; Tatiana S. Ribeiro; José M. Marconcini; Caue Ribeiro (156-162).
Despite the extensive research about polymer/clay composites and nanocomposites, there have been few investigations devoted to the resistance of these hybrids against ultraviolet radiation. This property is especially of interest for materials based on biodegradable polymers since they could be applied for slow release of light-degradable molecules, such as herbicides. This paper describes the photoprotective effect of starch/montmorillonite composites on the ultraviolet-induced degradation of ametryne, a commercial herbicide. The starch/montmorillonite composites highly loaded with ametryne (50% by weight), and different contents of clay were produced by the starch gelatinization method. The results showed that encapsulation of ametryne by starch/montmorillonite composites is simple and possible to be done as a one-step procedure. It was shown that the main photodegradation mechanism involves herbicide volatilization, which was significantly reduced due to formation of composites with starch and montmorillonite. The composite presented a synergistic photoprotective effect between components. 13C solid-state nuclear magnetic resonance (13C-NMR) and FTIR spectroscopy indicated that the photoprotective effect is based on absorption of ultraviolet radiation by starch/montmorillonite composites, and not due to herbicide interaction with the hybrid structure. The novel composites for controlled or slow delivery of herbicides exhibited a promising efficiency in protecting active inputs against solar light degradation in field.
Keywords: Biocomposites; Herbicide; Photostability; Thermal stability;
Tunable release of silver nanoparticles from temperature-responsive polymer blends by R. Elashnikov; O. Lyutakov; Y. Kalachyova; A. Solovyev; V. Svorcik (163-169).
Polymer blends of thermoresponsive poly(N-isopropylacrylamide) and poly(methyl methacrylate) with in situ synthesized silver nanoparticles (AgNPs) are proposed as stimuli-responsive antimicrobial materials. AgNPs were prepared in the semi-dried polymer blends by N-methyl-2-pyrrolidone reduction. Temperature controlled kinetic of silver release was examined for different weight ratios of the polymers. Synthesized AgNPs were characterized by transmission electron microscopy and temperature-dependent releasing was analyzed by ultraviolet–visible and atomic absorption spectroscopies. Temperature-dependent changes of polymer matrices were observed by confocal microscopy and infrared spectroscopy. It was shown that the polymer weight ratio determines both, starting time and kinetic of nanoparticle release. Antibacterial activities of the prepared material were demonstrated on Gram-positive Staphylococcus aureus (S. aureus) and gram-negative Pseudomonas aeruginosa (P. aeruginosa). Quantitative evaluation of antimicrobial efficacy of prepared materials was performed on the base of inhibition zone size. It was shown that prepared materials could serve as effective antibacterial coating with quick antimicrobial response.
Keywords: Stimuli-responsive; Release; Silver nanoparticles; Antimicrobial; Coating;
Synthesis of sulfur-containing alternating copolymers by RAFT copolymerization of phenyl vinyl sulfides by Yohei Abiko; Aiko Matsumura; Kazuhiro Nakabayashi; Hideharu Mori (170-177).
An electron-donating S-vinyl monomer, phenyl vinyl sulfide (PVS), was copolymerized with electron-accepting monomers, such as maleic anhydride (MA), N-methyl maleimide (MMI), and N-phenyl maleimide (PMI), via a reversible addition–fragmentation chain transfer (RAFT) process. Among various chain transfer agents (CTAs), the trithiocarbonate-type CTA was found to be effective in achieving controlled copolymerizations of PVS with the electron-accepting monomers with a strong alternating tendency. The controlled nature of the RAFT copolymerization of PVS with PMI was confirmed by the formation of narrow polydispersity products, with the molecular weight being controlled by the monomer/CTA molar ratio, resulting in an observed linear increase in the molecular weight with the polymer yield. RAFT copolymerization of PVS with an asymmetrical divinyl monomer, N-vinyl maleimide, in the presence of the trithiocarbonate-type CTA allowed the synthesis of alternating copolymer with pendant double bonds, which were available for subsequent thiol-ene click reaction to produce novel sulfur-containing copolymers.
Keywords: Alternating copolymer; S-vinyl monomer; Reversible addition–fragmentation chain transfer (RAFT); Thiol-ene click reaction;
Efficacy of different generations and concentrations of PAMAM–NH2 on the performance and structure of TFC membranes by Yaghoub Mansourpanah; Zeinab Jafari (178-189).
In this work, several polyamide thin layer membranes were prepared and modified with polyamidoamine (PAMAM) dendrimers in different generations (G 0, G 1, and G 2) and different concentrations (0.5, 1.5 and 3 wt.%) to investigate the occurring changes in the performance and morphology of the prepared thin layers. SEM and AFM data (reinforced with SPM software) proved that the dense and compressed surfaces were fabricated by loading and increasing of the generations and concentrations of PAMAM. In addition, the MWCO of the membranes drastically decreased. The chemical properties of the surface were investigated with ATR-IR and the occurring changes were studied. The zeta potential measurements illustrated that the surface charge of the thin layers was changed with alteration in the generations and concentrations of PAMAM. Additionally, in some cases the rejection capability of NaCl increased over 90%. Furthermore, the contact angle results clearly demonstrated an enhancement in the hydrophilicity of the membranes. The flux recovery ratio of the thin layers increased from 63% (in the unmodified thin layer) to near 97% in the thin layer composed of 3 wt.% G 0.
Keywords: Interfacial polymerization; PAMAM dendrimers; Different generations; Hydrophilicity; Pore size;
Poly(dopamine)-assisted preparation of star poly(ethylene glycol)-based coatings: A detailed study of their protein resistance and application in CE by Chong Zhang; Lijuan Chen; Lin Tan; Xiajun Zheng; Yanmei Wang (190-201).
In this study, a set of well-defined multiarm star copolymers, hyperbranched poly(ethylenimine)-graft-poly(ethylene glycol) (bPEI-g-PEG) with different PEG grafting ratios were synthesized. The star PEG-based coatings were then prepared by immobilizing the corresponding copolymers onto poly(dopamine) (PDA)-coated substrates. The chemical composition, hydrophilicity, surface topography, and thickness of the coatings were studied by X-ray photoelectron spectroscopy (XPS), water contact angle (WCA), atomic force microscopy (AFM), and variable angle spectroscopic ellipsometry (VASE), respectively. Furthermore, the surface PEG chain density of star PEG-based coating was evaluated quantitatively and compared with that of linear PEG-based coating. Our results showed that the amount of proteins (albumin from bovine serum, fibrinogen, and lysozyme) adsorbed on the star PEG-based coating as measured by surface plasmon resonance (SPR) was found to be dependent on the surface PEG chain density, which was controlled by the polymer incubation concentrations and PEG grafting ratios. Generally, the star-shaped PEG gave the surface with higher PEG chain density than linear ones and the amount of adsorbed proteins decreased with increasing surface PEG chain density. At last, the star PEG-based coating was successfully applied into the capillary inner surface for protein separation by capillary electrophoresis (CE).
Keywords: Poly(dopamine); Multiarm star copolymer; Poly(ethylene glycol); Protein resistance; Capillary electrophoresis;