Synergistic effect of KI on the corrosion inhibition of a poly(diallylammonium chloride)-based cyclocopolymer containing bis-cationic motifs for mild steel corrosion in 20% formic acid

This study entails the syntheses of a homopolymer, poly(diallylammonium chloride) (3), and copolymers (8a-c) containing hydrophilic/hydrophobic pendants and their role in mitigating mild steel in aggressive 20% formic acid, a type of corrosion that is not frequently discussed in the literature. The synthesized homopolymer and copolymers were characterized by FTIR, NMR, viscometry, and TGA. Inhibitor 8b was found to be the most potent, with 81.8% inhibition efficiency (IE) registered via the potentiodynamic polarization method for 100 ppm of inhibitor concentration at 30 °C. Inhibitor 8b, mixed with 2 mmol KI, showed more than 90% IE for a meager 1 ppm inhibitor concentration. For a synergism of 50 ppm inhibitor and 2 mmol KI, the IE reached a high value of 99.1%. The synergism was so good that it helped the inhibitor retain ∼100% of its original IE even after a 24 h weight loss study at 60 °C. The adsorption isotherm study showed that 8b followed the Langmuir adsorption isotherm and adsorbed via chemisorption. A very high value (2.48 × 105 L mol-1) of the equilibrium adsorption constant (Kads) indicated strong adsorption. XPS and SEM surface studies provided evidence of the inhibitor found on the metal surface. Some toxicological parameters, such as LC50, bioaccumulation factor, and developmental toxicity, have been measured computationally. A brief mechanistic insight into how the inhibitors functioned has been offered along with the DFT study.

Polymeric surfactants as ideal substitutes for sustainable corrosion protection: A perspective on colloidal and interface properties

Surfactants are well known for their colloidal and corrosion inhibition potential (CIP) due to their strong propensity to interact with metallic surfaces. However, because of their small molecular size and the fact that they are only effective at relatively high concentrations, their application in aqueous phase corrosion inhibition is often restricted. Polymeric surfactants, a unique class of corrosion inhibitors, hold the potential to eradicate the challenges associated with using surfactants in corrosion inhibition. They strongly bond with the metallic surface and offer superior CIP because of their macromolecular polymeric structure and abundance of polar functional groups. In contrast to conventional polymeric corrosion inhibitors, the inclusion of polar functional groups also aids in their solubilization in the majority of popular industry-based electrolytes. Some of the major functional groups present in polymeric surfactants used in corrosion mitigation include O (ether), glycidyl (cyclic ether), -CONH2 (amide), -COOR (ester), -SO3H (sulfonic acid), -COOH (carboxyl), -NH2 (amino), - + NR3/- + NHR2/- + NH2R/- + NH3 (quaternary ammonium), -OH (hydroxyl), -CH2OH (hydroxymethyl), etc. The current viewpoint offers state-of-the-art information on polymer surfactants as newly developing ideal alternatives for conventional corrosion inhibitors. The industrial scale-up, colloidal, coordination, adsorption properties, and structural requirements of polymer surfactants have also been established based on the knowledge obtained from the literature. Finally, the challenges, drawbacks, and potential benefits of using polymer surfactants have also been discussed.

Stimuli-Responsive Macromolecular Architecture by Butler Cyclopolymerizations: Synthesis and Applications

This article reviews the synthesis of polyzwitterions (PZs) (poly-carboxybetaines, -phosphonobetaines, and -sulfobetaines) having multiple pH-responsive centers. The synthesis follows the Butler cyclopolymerization protocol involving a multitude of diallylammonium salts and their copolymerization with SO₂ and maleic acid. The PZs have been transformed into cationic-, anionic-polyelectrolytes, and polyampholytes under the influence of pH. Particular attention is given to the application of these polymers as antiscalants, mild steel corrosion inhibitors, components in constructing Aqueous Two-Phase Systems (ATPSs), and membrane modifiers. The ATPSs could be used to separate various biomolecules, including proteins. Many amphiphilic polymers incorporating a few mol % hydrophobic monomers have shown enhanced viscosities and could be suitable for applications in oil fields. The progress of applying Butler cyclopolymerization in reversible addition-fragmentation chain transfer (RAFT) chemistry has been discussed. Future works are expected to focus on RAFT cyclopolymerization to construct block copolymers.

A sorbent containing pH-responsive chelating residues of aspartic and maleic acids for mitigation of toxic metal ions, cationic, and anionic dyes

t-Butyl hydroperoxide-initiated cycloterpolymerization of diallylaminoaspartic acid hydrochloride [(CH2[double bond, length as m-dash]CHCH2)2NH+CH(CO2H)CH2CO2H Cl-] (I), maleic acid (HO2CH[double bond, length as m-dash]CHCO2H) (II) and cross-linker tetraallylhexane-1,6-diamine dihydrochloride [(CH2[double bond, length as m-dash]CHCH2)2NH+(CH2)6NH+ (CH2CH[double bond, length as m-dash]CH2)2 2Cl-] (III) afforded a new pH-responsive resin (IV), loaded with four CO2H and a chelating motif of NH+⋯CO2 - in each repeating unit. The removal of cationic methylene blue (MB) (3000 ppm) at pH 7.25 and Pb(ii) (200 ppm) at pH 6 by IV at 298, 313, and 328 K followed second-order kinetics with E a of 33.4 and 40.7 kJ mol-1, respectively. Both MB and Pb(ii) were removed fast, accounting for 97.7% removal of MB within 15 min at 313 K and 94% of Pb(ii) removal within 1 min. The super-adsorbent resin gave respective q max values of 2609 mg g-1 and 873 mg g-1 for MB and Pb(ii). IV was also found to trap anionic dyes; it removed 91% Eriochrome Black T (EBT) from its 50 ppm solutions at pH 2. The resin was found to be effective in reducing priority metal contaminants (like Cr, Hg, Pb) in industrial wastewater to sub-ppb levels. The synthesis of the recyclable resin can be easily scaled up from inexpensive starting materials. The resin has been found to be better than many recently reported sorbents.

A resin containing motifs of maleic acid and glycine: a super-adsorbent for adsorptive removal of basic dye pararosaniline hydrochloride and Cd(II) from water

The cyclocopolymerization of N,N-diallylglycine hydrochloride, maleic acid and 1,1,4,4-tetraallylpiperazinium dichloride afforded a cross-linked polyzwitterionic acid, which, upon treatment with NaOH, gave the corresponding cross-linked anionic polyelectrolyte (CAPE) in quantitative yield. The pH-responsive resins contained a high density of CO2 - motifs as well as the chelating motifs of glycine residues. The resin CAPE was found to be a super-adsorbent for the removal of pararosaniline hydrochloride (PRH); having a q max of 1534 mg/g. The adsorption process followed pseudo-second-order kinetics and was found to be a nearly irreversible process as suggested by the parameters obtained from Elovich kinetic model. The resin demonstrated excellent adsorption/desorption efficiencies, thereby ensuring its recycling and reuse in potent applications like remediation of industrial dye-waste water. The resin's chelating motifs were also efficient in the adsorptive removal of Cd(II) ions with a q max of 248 mg/g. It was also employed for the simultaneous and effective trapping of Cd(II) and the dye from industrial wastewater. The resin's impressive performance accords it a prestigious place among many sorbents in recent works.

Design and Synthesis of a Dual-Purpose Superadsorbent Containing a High Density of Chelating Motifs for the Fast Mitigation of Methylene Blue and Pb(II)

Maleic acid underwent alternate copolymerization with diallylaminomethylphosphonic acid·HCl [(CH2=CHCH2)2NH+CH2PO3H2 Cl-] and a cross-linker to give a new pH-responsive resin. Methylene blue (MB) removal from its 3000 ppm solution by the resin at pH 7 followed second-order kinetics with an E a of 34.8 kJ mol-1. MB removal was achieved very fast (10 min), attaining over 98.5% at 328 K. The q e obtained using MB concentrations in the range 100-8000 ppm fitted the Langmuir nonlinear isotherm model to give ΔG o, ΔH o, and ΔS o values of ≈ -21 kJ, 36.5 kJ mol-1, and 185 J mol-1 K-1, respectively. The resin is a superadsorbent with a q max value of 2445 mg g-1. The adsorbent also removed 97% Pb(II) within 5 min from its 10 000 ppb solution. The resin reduced the Pb(II) concentration from 200 to 3.8 ppb. The resin also demonstrated its ability to remove contaminants from industrial wastewater, reducing priority metal contaminants to ppb and sub-ppb levels. The resin can be recycled with stable efficiency. The outstanding performance places the resin in a top position in a list of recently reported sorbents.

Fast removal of methylene blue and Hg(II) from aqueous solution using a novel super-adsorbent containing residues of glycine and maleic acid

The alternate cyclo-copolymerization of diallylammonioethanoate [(CH₂=CHCH₂)₂NCH₂CO₂^-] and maleic acid in the presence of a cross-linker afforded a novel pH-responsive resin (90% yield). The resin has turned out to be a super-adsorbent for methylene blue (MB) removal with a q_Max of 2101 mg g^-1. The adsorption of the dye followed pseudo second-order kinetics with an energy of activation (E_a) of 31.5 kJ mol^-1. The process showed an extraordinarily fast adsorption rate owing to faster film diffusion; the resin (250 mg) was able to trap 78 and 99.4% MB from its 3000 mg L^-1 solution (100 mL) within 3 and 30 min, respectively. Equilibrium constants from Langmuir nonlinear isotherm model in the range 288-328 K gave ΔG^o ΔH^o, and ΔS^o values of ≈ -25 kJ, -13 kJ and 39.5 J mol^-1 K^-1, respectively. Immobilization mechanism was discussed using FTIR, SEM, and Elovich kinetic model. The presence of the chelating glycine residues was exploited for the removal of Hg(II) ions; the q_Hg was determined to be 263 mg g^-1. The resin also removed MB and Hg(II) simultaneously from industrial wastewater with remarkable efficacy. The very impressive performance along with efficient recycling conferred the resin a top position among many sorbents.

Scope of sulfur dioxide incorporation into alkyldiallylamine-maleic acid-SO2 tercyclopolymer

Alternate copolymerization of diallylamine derivatives [(CH₂CH Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> CH₂)₂NR; R = Me, (CH₂)₃PO(OEt)₂, and CH₂PO(OEt)₂] (I)–maleic acid (MA) and (I·HCl)–SO₂ pairs have been carried out thermally using ammonium persulfate initiator as well as UV radiation at a λ of 365 nm. The reactivity ratios of ≈0 for the monomers in each pair I–MA and I·HCl–SO₂ ensured their alternation in each copolymer. However, numerous attempted terpolymerizations of I–MA–SO₂ failed to entice MA to participate to any meaningful extent. In contrast to reported literature, only 1–2 mol% of MA was incorporated into the polymer chain mainly consisting of poly(I-alt-SO₂). Quaternary diallyldialkylammonium chloride [(CH₂CH–CH₂)₂N⁺R₂Cl⁻; R = Me, Et] (II) also, did not participate in II–MA–SO₂ terpolymerizations. Poly((I, R = Me)-alt-SO₂) III is a stimuli-responsive polyampholyte; its transformation under pH-induced changes to cationic, polyampholyte-anionic, and dianionic polyelectrolytes has been examined by viscosity measurements. The pK_a of two carboxylic acid groups and NH⁺ in III has been determined to be 2.62, 5.59, and 10.1. PA III, evaluated as a potential antiscalant in reverse osmosis plants, at the concentrations of 5 and 20 ppm, imparted ≈100% efficiency for CaSO₄ scale inhibition from its supersaturated solution for over 50 and 500 min, respectively, at 40 °C. The synthesis of PA III in excellent yields from cheap starting materials and its very impressive performance may grant PA III a prestigious place as an environment-friendly phosphate-free antiscalant.

Alternate copolymerization of diallylamine derivatives [(CH₂=CH–CH₂)₂NR; R = Me, (CH₂)_nPO(OEt)₂] (I)–maleic acid (MA) and (I·HCl)–SO₂ pairs have been carried out thermally using ammonium persulfate initiator as well as UV radiation at λ of 365 nm.

A new resin embedded with chelating motifs of biogenic methionine for the removal of Hg(II) at ppb levels

Cyclopolymerization of N,N-diallylmethionine hydrochloride, derived from the biogenic amino acid methionine, (90 mol%) and cross-linker tetraallylpiperazinium dichloride (10 mol%) in presence of an azo-initiator afforded pH-responsive cross-linked polyzwitterion (CPZ). The structural morphology of the resin (i.e. CPZ) was examined by the BET and FESEM-EDX analyses. The methionine embedded resin demonstrated remarkable efficacies for the removal of Hg(II) ions at ppb levels. A 50 mg-dose of the resin immersed in aqueous medium (18 mL) could reduce the concentration of Hg(II) from 200 and 400 ppb to 1.8 and 4.4 ppb, respectively, within 15 min. The resin has also proven to be remarkably effective in the removal of several toxic and priority metal pollutants from industrial wastewater. The Hg(II) adsorption followed pseudo second-order process with E_a of 48.1 kJ mol^-1. The initial rapid adsorption of metal ions and subsequent slower adsorption was attributed to film and intraparticle diffusion, respectively. The SEM-EDX analyses revealed the attachment of Hg(II) ions onto the resin. The favorability of the endothermic adsorption was ensured by the negative ΔGº values. The efficient adsorption/desorption process confirmed the recyclability of the resin. The current resin demonstrated superior metal removal capacities as compared to several other adsorbents in recent works.

Imidazolines containing single-, twin- and triple-tailed hydrophobes and hydrophilic pendants (CH2CH2NH)nH as inhibitors of mild steel corrosion in CO2–0.5 M NaCl

The study assesses the effects of single-, twin- and triple-tailed imidazolines andN-pendants on the inhibition of mild steel corrosion in CO₂–saturated-0.5 M NaCI.

Mechanically enhanced microcapsules for cellular gene therapy

Microcapsules bearing a covalently cross-linked coating have been developed for cellular gene therapy as an improvement on alginate-poly(L-lysine)-alginate (APA) microcapsules that only have ionic cross-linking. In this study, two mutually reactive polyelectrolytes, a polycation (designated C70), poly([2-(methacryloyloxy)ethyl]trimethylammonium chloride-co-2-aminoethyl methacrylate hydrochloride) and a polyanion (designated A70), poly(sodium methacrylate-co-2-(methacryloyloxy)ethyl acetoacetate), were used during the microcapsule fabrication. Ca-alginate beads were sequentially laminated with C70, A70, poly(L-lysine) (PLL), and alginate. The A70 reacts with both C70 and PLL to form a approximately 30 microm thick covalently cross-linked interpenetrating polymer network on the surface of the capsules. Confocal images confirmed the location of the C70/A70/PLL network and the stability of the network after 4 weeks implantation in mice. The mechanical and chemical resistance of the capsules was tested with a "stress test" where microcapsules were gently shaken in 0.003% EDTA for 15 min. APA capsules disappeared during this treatment, whereas the modified capsules, even those that had been retrieved from mice after 4-weeks implantation, remained intact. Analysis of solutions passing through model flat membranes showed that the molecular weight cut-off of alginate-C70-A70-PLL-alginate is similar to that of alginate-PLL-alginate. Recombinant cells encapsulated in APA and modified capsules were able to secrete luciferase into culture media. The modified capsules were found to capture some components of regular culture media used during preparation, causing an immune reaction in implanted mice, but use of UltraCulture serum-free medium was found to prevent this immune reaction. In vivo biocompatibility of the new capsules was similar to the APA capsules, with no sign of clinical toxicity on complete blood counts and liver function tests. The increased stability of the covalently modified microcapsules coupled with the acceptable biocompatibility and permeability demonstrated their potential for use as immunoisolation devices in gene therapy.