Ionic Linkages Research Articles

Modulating Ionic Linkages in the Heterocyclic Sulfated Polysaccharide Carrageenan for Enhanced Selectivity Against Amelanotic Melanoma Cells

AbstractThe present research is the use of Heterocyclic sulfated polysaccharides, exemplified by carrageenan, with the high selective anti‐cancer against melanoma cancer. This study focuses on optimizing the ionic linkage of carrageenan to enhance its selectivity and activity against skin cancer cells with the help of cell line assays and in‐silico studies. The cytotoxicity and selectivity of the optimized derivatives were assessed in‐vitro against skin cancer cells and normal skin cells. The barium‐linked carrageenan demonstrated significantly increased selectivity against skin cancer cells with a selectivity index of 45, however, the reference drug was found with a selectivity index of 23. The selectivity of the compound 3 (Ba ion linked) was analysed through the ion dissociation energy and found that the more energy is require to dissoxiate in the ion, which signifiacnlty absorbs inside the cell because of non‐ionic form. The selectivity sequence of K+<Ca2+<Ba2+ as a targeted anti‐cancer agent. The present research unfold the importance of ion linkage of chromophore, to get the more active and selective compounds, which will be a path to get the ion activity relationship of various drugs without interfering the chromophore. The findings suggest a promising avenue for the development of targeted therapies with the change of ions, emphasizing the potential of heterocyclic sulfated polysaccharides in the field of cancer treatment with enhanced tuning of selectivity. The further scope is the gel formation of the Ba2+ carrageenan which will be the first API (Active Pharmaceuitical Ingredients) based formulation for skin cancer.

Ligand-Assisted Direct Lithography of Upconverting and Avalanching Nanoparticles for Nonlinear Photonics.

Upconverting nanoparticles (UCNPs) exhibit unique nonlinear optical properties that can be harnessed in microscopy, sensing, and photonics. However, forming high-resolution nano- and micropatterns of UCNPs with large packing fractions is still challenging. Additionally, there is limited understanding of how nanoparticle patterning chemistries are affected by the particle size. Here, we explore direct patterning chemistries for 6-18 nm Tm3+-, Yb3+/Tm3+-, and Yb3+/Er3+-based UCNPs using ligands that form either new ionic linkages or covalent bonds between UCNPs under ultraviolet (UV), electron-beam (e-beam), and near-infrared (NIR) exposure. We study the effect of UCNP size on these patterning approaches and find that 6 nm UCNPs can be patterned with compact ionic-based ligands. In contrast, patterning larger UCNPs requires long-chain, cross-linkable ligands that provide sufficient interparticle spacing to prevent irreversible aggregation upon film casting. Compared to approaches that use a cross-linkable liquid monomer, our patterning method limits the cross-linking reaction to the ligands bound on UCNPs deposited as a thin film. This highly localized photo-/electron-initiated chemistry enables the fabrication of densely packed UCNP patterns with high resolutions (∼1 μm with UV and NIR exposure; <100 nm with e-beam). Our upconversion NIR lithography approach demonstrates the potential to use inexpensive continuous-wave lasers for high-resolution 2D and 3D lithography of colloidal materials. The deposited UCNP patterns retain their upconverting, avalanching, and photoswitching behaviors, which can be exploited in patterned optical devices for next-generation UCNP applications.

Spiroborate-Linked Ionic Covalent Adaptable Networks with Rapid Reprocessability and Closed-Loop Recyclability

Covalent adaptable networks (CANs) represent a novel class of polymeric materials crosslinked by dynamic covalent bonds. Since their first discovery, CANs have attracted great attention due to their high mechanical strength and stability like conventional thermosets under service conditions and easy reprocessability like thermoplastics under certain external stimuli. Here, we report the first example of ionic covalent adaptable networks (ICANs), a type of crosslinked ionomers, consisting of negatively charged backbone structures. More specifically, two ICANs with different backbone compositions were prepared through spiroborate chemistry. Given the dynamic nature of the spiroborate linkages, the resulting ionomer thermosets display rapid reprocessability and closed-loop recyclability under mild conditions. The materials mechanically broken into smaller pieces can be reprocessed into coherent solids at 120 °C within only 1 min with nearly 100% recovery of the mechanical properties. Upon treating the ICANs with dilute hydrochloric acid at room temperature, the valuable monomers can be easily chemically recycled in almost quantitative yield. This work demonstrates the great potential of spiroborate bonds as a novel dynamic ionic linkage for development of new reprocessable and recyclable ionomer thermosets.

Preparation and characterization of carbon quantum dot‐hydroxyapatite‐alginate based hybrid fluorescent ink for sensor application

AbstractDevelopment of multifunctional fluorescent inks is gaining attention owing to the current technological developments in optoelectronics. The present work involves the development of a simple and highly fluorescent carbon quantum dot (CQD)‐based nano‐ink suitable for sensor and bioimaging applications. CQDs were synthesized by a one‐pot hydrothermal method using folic acid (FA) a carbon source. The synthesized CQDs were conjugated with hydroxyapatite (HAP) and sodium aliginate (SA) by covalent and ionic linkages methods. Fourier transform infrared (FT‐IR) spectra confirm the formation of nano‐inks by the ionic interaction between the HAP and SA and conjugation with CQDs through hydrogen bonding. The surface morphology of the CQDs and nano‐inks depicts that the particles exhibit in spherical and needle‐like morphological structures, respectively. The X‐ray diffraction (XRD) pattern confirms that the obtained CQDs and fluorescent nano‐ink are highly crystalline in nature. The SA and HAP provided shear thinning ability and structural stability for the fluorescent nano‐ink. The nano‐ink‐based strips displayed high fluorescence under Ultraviolet irradiation. The fluorescent nano‐ink could be used in bioimaging, flourescent coatings, and anti‐counterfeiting applications.

Probing the structural features of a plasma-treated chitosan-acrylic acid hydrogel

This study explored the use of atmospheric pressure plasma in preparing a chitosan-acrylic acid (Cs-AA) hydrogel. Cs, the backbone of the hydrogel, has its structure confirmed using spectroscopic techniques such as X-ray photoelectron spectroscopy, near edge X-ray fine structure spectroscopy, and Fourier transform infrared spectroscopy. The presence of CO confirmed the presence of AA. AA promoted the formation of protonated amine. This creates the ionic linkage of the hydrogel network. Plasma treatment using compressed air created an inductive effect on the C-O species of the Cs backbone. Using N2 as working gas, there was an increase in the protonated amines in the Cs backbone, specially at high Cs concentration, aside from the inductive effect in the C-O species. This was confirmed from the shifts in the binding energy and photon energy values between the Cs and AA polymers. A combination of ionic and covalent linkages established the network of the Cs-AA hydrogel. The study showed that atmospheric pressure plasma treatment can be used not only for surface functionalization but also facilitating crosslinking of Cs and AA.

UV-Cured Cross-Linked Astounding Conductive Polymer Electrolyte for Safe and High-Performance Li-Ion Batteries.

UV-cured cross-linked polymer electrolytes are promising electrolytes for safe Li-ion batteries (LIBs) application due to their excellent conduction ability, low glass-transition temperature (Tg), and high discharge capacity. Herein, we have prepared novel fluorosulfonylimide methacrylic-based cross-linked polymer electrolyte membranes for LIBs via UV-curing process, which is a well-known, easy, low-cost, fast, and reliable technique. The synthesized UV-reactive novel methacrylate monomer with directly attached fluorosulfonylimide functional group methacryloylcarbamoyl sulfamoyl fluoride (MACSF) was used as a precursor for UV curing along with poly(ethylene glycol) dimethacrylate (PEGDMA) and lithium bis(fluorosulfonyl)imide (LiFSI). The results demonstrated that the cross-linked membrane with an optimized amount (30 wt %) of MACSF monomer (noted as CPE-3) showed the best performance. The nonflammable fluorosulfonyl group (a hydrophilic group of MACSF monomer) in the polymer matrix formed a wide channel, as a result of which Li ion can migrate easily via forming an ionic linkage. The CPE-3 electrolyte exhibited a low Tg (-79 °C), excellent phase separation, high conductivity (σ) (ca. 3.5 × 10-4 and 8.50 × 10-3 S·cm-1 at 30 and 80 °C, respectively), and high flame retardancy. The battery performance of half-cell (LiFePO4/CPE-3/Li) and full cell (LiFePO4/CPE-3/graphite) with CPE-3 electrolyte were attractive: discharge capacities (155 and 152 mAh/g) with the capacity retentions of 96.17 and 95.17% after 500 cycles at 0.1 C rate for half-cell and full-cell LIBs, respectively.

Combination of Self-Healing Butyl Rubber and Natural Rubber Composites for Improving the Stability.

The self-healing composites were prepared from the combination of bromobutyl rubber (BIIR) and natural rubber (NR) blends filled with carbon nanotubes (CNT) and carbon black (CB). To reach the optimized self-healing propagation, the BIIR was modified with ionic liquid (IL) and butylimidazole (IM), and blended with NR using the ratios of 70:30 and 80:20 BIIR:NR. Physical and chemical modifications were confirmed from the mixing torque and attenuated total reflection-fourier transform infrared spectroscopy (ATR-FTIR). It was found that the BIIR/NR-CNTCB with IL and IM effectively improved the cure properties with enhanced tensile properties relative to pure BIIR/NR blends. For the healed composites, BIIR/NR-CNTCB-IM exhibited superior mechanical and electrical properties due to the existing ionic linkages in rubber matrix. For the abrasion resistances, puncture stress and electrical recyclability were examined to know the possibility of inner liner applications and Taber abrasion with dynamic mechanical properties were elucidated for tire tread applications. Based on the obtained Tg and Tan δ values, the composites are proposed for tire applications in the future with a simplified preparation procedure.

Covalent and Ionic Bonding between Tannin and Collagen in Leather Making and Shrinking: A MALDI-ToF Study

Collagen powder hydrolysates were reacted with a solution of commercial mimosa bark tannin extract. The mixture was prepared at ambient temperature and prepared at 80°C to determine what reactions, if any, did occur between the collagen protein through its amino acids and the polyphenolic condensed tannin. The reaction products obtained were analyzed by matrix assisted laser desorption ionization time-of-flight (MALDI ToF) mass spectrometry. Reactions between the two materials did appear to occur, with the formation of a relatively small proportion of covalent and ionic linkages at ambient temperature but a considerable proportion of covalent linkages tannin-protein amino acids and the disappearance of ionic bonds. The linkages between the two materials appeared to be by amination of the phenolic –OHs of the tannin by the amino groups of the non-skeletal side chains of arginine, and by esterification by the –COOH groups of glutamic and aspartic acid of the aliphatic alcohol-OH on the C3 site of the flavonoid units heterocycle of the tannin. The proportion of covalent linkages increases markedly and predominate with increasing temperatures. This tightening of the tannin-protein covalent network formed may be an additional contributing factor both to leather wear resistance and performance as well to leather shrinking when this is subjected to excessive temperatures.

Structural, elastic, optical and γ-ray shielding behavior of Dy3+ ions doped heavy metal incorporated borate glasses

The effect of modifier ions in different basis have been analyzed through a new series of heavy metals incorporated borate based glasses 39H3BO3+30PbO+20MO+10Bi2O3 +1Dy2O3 (where M=Ca,Sr,Ba,Na and K) which are synthesized following melt quenching technique for radiation screening applications. The potentiality of glasses to withstand the penetration of fast moving neutrons is checked by various studies. Functional groups are identified through different stretching and bending modes of vibrations within the glass membrane through FTIR spectral analysis. In addition to that, other structural properties like Boron-Boron distance (dB−B), molar volume of oxygen (Vo), Oxygen Packing Density (OPD), optical basicity (Λth) and Bond density (nb) are calculated theoretically. The bonding nature (β) and nephelauxetic ratio (δ) values reveals that the glasses possess more of ionic linkages. The high density value exhibited by the Bismuth lead borate glasses indicates their capability to act as a good shielding material in reactors emitting hazardous radiation. Different moduli of elasticity (E, K, G, σ) values for the present glasses are calculated and the results reveal the enhancement in shielding performances when compared to other existing glasses and a comparative study is made on it. Optical studies are carried out and the absorption of Dy3+ions to different energy levels is observed and optical band gap (Eopt) values of the synthesized glasses are calculated along with the Urbach energy (ΔE) values. Radiation shielding properties of the produced glasses were investigated in terms of the mass attenuation coefficients (µm), transmission fraction (T), half value layer (HVL) and effective atomic number (Zeff) parameters. The results attained in the shielding study indicated that glass specimen with M = Ba exhibits enhanced shielding behavior as Ba owns high atomic number (Z) compared to other elements. Glass specimen with M = Na shows the poorest shielding characteristics due to the low Z of Na.

Enzyme immobilization and its applications in food processing: A review

The “immobilized enzymes” are the enzymes physically confined or localized in a certain defined region of space with retention of their catalytic activities which can be used repeatedly and continuously. Enzyme immobilization provides an excellent base for increasing availability of enzyme to the substrate with greater turnover over a considerable period of time. Immobilized enzymes are preferred over their free counterpart due to their prolonged availability that reduces redundant downstream and purification processes. The enzymes can be attached to the support by interactions ranging from reversible physical adsorption and ionic linkages to stable covalent bonds. The choice of the most appropriate immobilization technique depends on the nature of the enzyme and the carrier. Such techniques produce immobilized enzymes of varying stability due to changes in the surface microenvironment and degree of multipoint attachment. The industrial applications of immobilised enzymes are progressively increasing. Immobilized enzymes find use in a number of biotechnological products with applications in diagnostics, bio affinity chromatography, and biosensors. Immobilised enzymes find wide applications in the food industry. With these immobilised enzymes, it is possible to obtain different types of sugar syrups, lactose free milk, clarified and debittered juices and wines. Immobilised enzymes can be employed for the production of different active packaging material like oxygen scavenging, anti-microbial films. However, commercialization of immobilized enzymes is still at a slower pace because of their costs and storage problems. Research should be focused to overcome the current limitations related to immobilization techniques, so as to expand the horizon for all-round application. In future, immobilized enzymes are going to play a vital role in various industries including pharmaceuticals, chemicals, food and fuel.

Tunable Adhesion from Stoichiometry-Controlled and Sequence-Defined Supramolecular Polymers Emerges Hierarchically from Cyanostar-Stabilized Anion-Anion Linkages.

Sequence-controlled supramolecular polymers offer new design paradigms for generating stimuli-responsive macromolecules with enhanced functionalities. The dynamic character of supramolecular links present challenges to sequence definition in extended supramolecular macromolecules, and design principles remain nascent. Here, we demonstrate the first example of using stoichiometry-control to specify the monomer sequence in a linear supramolecular polymer by synthesizing both a homopolymer and an alternating copolymer from the same glycol-substituted cyanostar macrocycle and phenylene-linked diphosphate monomers. A 2:1 stoichiometry between macrocycle and diphosphate produces a supramolecular homopolymer of general formula (A)n comprised of repeating units of cyanostar-stabilized phosphate-phosphate dimers. Using a 1:1 stoichiometry, an alternating (AB)n structure is produced with half the phosphate dimers now stabilized by the additional counter cations that emerge hierarchically after forming the stronger cyanostar-stabilized phosphate dimers. These new polymer materials and binding motifs are sufficient to bear normal and shear stress to promote significant and tunable adhesive properties. The homopolymer (A)n, consisting of cyanostar-stabilized anti-electrostatic linkages, shows adhesion strength comparable to commercial superglue formulations based on polycyanoacrylate but is thermally reversible. Unexpectedly, and despite including traditional ionic linkages, the alternating copolymer (AB)n shows weaker adhesion strength more similar to commercial white glue based on poly(vinyl acetate). Thus, the adhesion properties can be tuned over a wide range by simply controlling the stoichiometric ratio of monomers. This study offers new insight into supramolecular polymers composed of custom-designed anion and receptor monomers and demonstrates the utility of emerging functional materials based on anion-anion linkages.

Nanocomposite Grafted Stretchable and Conductive Ionic Hydrogels for Use as Soft Electrode in a Wearable Electrocardiogram Monitoring Device

Hydrogels possessing stretchability, toughness, and conductivity together are promising candidates for soft electronics applications. In this report, ionic grafting of poly(acryloyl hydrazide) (PAHz)–silver (Ag) nanocomposites (NC) is used to improve the mechanical properties and conductivity of poly(acrylamidopropanesulfonic acid) (PAMPS) hydrogels. PAHz–Ag NCs possessing different sizes of Ag NPs (3–40 nm) are grafted in the PAMPS hydrogel matrix via −CONHNH3+---–O3S ionic linkage. The resulting PAHz–Ag NC grafted hydrogels at ∼62 wt % water content exhibited ultimate tensile strength (UTS) and fracture energy up to ∼1.14 MPa and ∼1600 J/m2, respectively. The UTS of hydrogels was dependent on the size of Ag NP in PAHz–Ag NCs, and the value increased from 0.70 to 1.14 MPa with the decrease in Ag NP size from ∼40 to 5 nm. The hydrogel samples exhibited adequate skin adhesiveness (tack adhesive strength ≈10.8 kPa), conductivity (50.5 mS/cm), and strain sensing ability (gauge factor ≈0.9), suggesting these samples are potentially useful for various soft electronics applications. As a proof of concept, the hydrogels were employed as soft electrode in an electrocardiogram (ECG) device, and the efficiency was monitored under real-time conditions. The data exhibited noise-free reproducible patterns of ECG with defined P, Q, R, S, and T peaks under different locomotion of the body, suggesting the viability of developed hydrogels for the ECG sensing applications.

Suppression mechanism of l-arginine in the heat-induced aggregation of bighead carp (Aristichthys nobilis) myosin: The significance of ionic linkage effects and hydrogen bond effects

The suppression mechanism of l-arginine (Arg) in fish myosin heat-induced aggregation was investigated in this work. The hydrodynamic radius determined by dynamic light scattering (DLS) and the turbidity of a myosin solution decreased in a dose-dependently manner with Arg after heating, especially in a solution without pH modification (P < 0.05). The surface hydrophobicity of myosin exhibited the same trend as that for hydrodynamic radius and turbidity (P < 0.05). The myosin secondary structures clearly changed with Arg concentration during heating (P < 0.05). These results demonstrate that positively-charged Arg could form ionic interactions with negatively charged myosin, as well as promote repulsion between myosin molecules induced by higher pH values. Furthermore, the resultant hydrogen bonding observed indicated that, in addition to Arg having ionic linkage effects, the specific structure of Arg played an important role in the suppression of myosin aggregation. Essentially, Arg markedly disturbed the hydrogen bonds of the myosin backbone and formed new hydrogen bonds with myosin molecules via two amino groups (-NH2), which are part of the guanidinium moiety of Arg, preferentially hydrogen bonding with the backbone carbonyl oxygen atoms of myosin molecules. This work provides support for using Arg as an additive to modify the texture of fish products to produce liquid and semiliquid food suitable for the elderly consumers in an aging society.

Zinc salts induced ionomeric thermoplastic elastomers based on XNBR and PA12

ABSTRACTIonomeric TPEs of XNBR and PA12 have been prepared in presence of various zinc salts such as Zinc oxide (ZnO), Zinc peroxide (ZnO2) and combination of (ZnO+ZnO2). Curing study of XNBR in presence of ZnO, ZnO2 and (ZnO+ZnO2) depicts a significant difference in torque values which suggests the formation of both ionic and covalent linkages for ZnO2 crosslinked XNBR whereas the only ionic crosslink formation takes place for ZnO crosslinked XNBR. Further morphology study by scanning electron microscopy (SEM), atomic force microscopy (AFM), physicomechanical properties, dynamic mechanical thermal analysis (DMTA), rheological study and swelling study also supports the above phenomenon.

Synthesis and structures of bis(iminophosphorano)methanide chelate complexes with zinc and group 13

The organolithium bis(iminophosphorano)methandiide dimer [Li2C(Ph2PNSiMe3)2]2 ([Li2-1]2) reacts with 4 equiv of AlCl3 in THF to generate the novel bimetallic aluminum carbene complex of [Li(THF)4][{C(Ph2PNSiMe3)2}Al2Cl5] (1). In addition, several new bis(iminophosphorano)methanide chelate-coordinated complexes of [{CH(Ph2PNSiMe3)2}AlCl2] (2), [{CH(Ph2PNSiMe3)2}GaBr2] (3), [{CH(Ph2PNSiMe3)2}InCl2] (4), and [{CH(Ph2PNSiMe3)2}InBr2] (5) are synthesized in situ while organolithium bis(iminophosphorano)methandiide ([Li2-1]2) reacts with 2 equiv of metal halides AlCl3, GaBr3 InCl3 and InBr3 respectively in THF. Furthermore, an unexpected complex of [{CH2(Ph2PNSiMe3)2}ZnCl2] (6) is formed as [Li2-1]2 dimer reacted with 2 equiv of ZnCl2 in situ. All six synthesized complexes (1, 2, 3, 4, 5 and 6) in situ were isolated in solid and were structurally characterized by X-ray diffraction. Complexes containing particular carbene to metal or ionic linking interaction bonds (1, 2, 3 and 4) were selected and further characterized in detail by DFT calculations using Gaussian03 program. The DFT calculation demonstrates the existence of a carbeneAl σ bond in structure 1 and ionic linkage interaction in structures 2–4.

Effects of different NaCl concentrations on self-assembly of silver carp myosin

The effect of NaCl (0.1 − 3.0 M) on self-assembly of silver carp myosin at 4 °C was investigated in terms of microstructure, conformation, intermolecular interactions, and particle size distribution. During setting at 4 °C, the self-assembly of myosin showed an obvious concentration dependence. At low concentrations (<0.3 M), myosin assembled into filaments mainly through rod-rod ionic linkages, and showed significantly (P < 0.05) higher turbidity and lower solubility than at ≥0.3 M. The addition of NaCl (0.3 − 0.6 M) led to the extension and dissolution of myosin by interfering with electrostatic interactions. The myosin assemblies gradually became smaller and more uniform. The solubility and Ca2+-ATPase activity reached a maximum at 0.6 M NaCl. When the concentrations increased to >1.0 M, myosin further assembled into filaments dominated by hydrophobic interactions. Both rod-rod and head-head interactions contributed to the myosin filaments at high concentrations (1.0 − 3.0 M). The solubility and uniformity of the myosin assemblies decreased as the NaCl concentration increased from 1.0 to 3.0 M.

Template method for dual network self-healing hydrogel with conductive property

We herein present dual-network self-healing hydrogels via ionic cross-linking and hydrogel bonds based on chitosan molecular chain as a template. Chitosan and poly(acrylic acid) were reacted to form a dual-network structure via Fe3+ ion coordination and hydrogen bonds. The healing property mainly depends on the coordination between Fe3+ ions and COOH or NH2 groups of the polymer chains, as well as on the hydrogen bonds occurring among OH, NH2 and COOH groups. Compared with the covalent cross-linking points, the ionic linkages and hydrogen bonds in the hydrogels were stochastic and dynamic. Hence, if the hydrogel becomes cracked or possesses a notch, the cross-linking points will be destroyed, while the new ones will be re-formed based on the dual-network of the hydrogel. The self-healing efficiency of the as-prepared hydrogel could reach 98.5% when the concentration range of 0.01–0.5M Fe3+ aqueous solution was used. In addition, both the compression resistance and electrical conductivity of the hydrogel were enhanced with FeCl3 content increasing. Therefore, the as-prepared hydrogel exhibited excellent stretchability, compression resistance, self-healing performance without any external stimulus, and electrical conductivity.

Recent developments and applications of protective silicone coatings: A review of PDMS functional materials

Abstract The classification of silicones in the literature is as broad as their properties and applications; in this work, we have restricted the discussion to polydimethylsiloxanes. Silicones, classified here as derivatives of polydimethylsiloxane (PDMS), are organically modified inorganic-type macromolecules of silicon with different molecular weights, sizes and chemical properties. The presence of the organic and inorganic components within these copolymers/oligomers/polymers accounts for their multi-phased chemistries since either covalent or ionic linkages connect their hybrid molecular chains. As ceramers derived via sol-gel type routes, some products of silicone syntheses result in functional materials with both physical and chemical properties intermediate between normal polymers and pristine ceramics. Hybrid materials of this kind form very stable chemical bonds on surfaces. The strong chemical bonding inherent within their siloxane ( Si O ) networks as well as their thermal stability promote inertness against chemical attack, hence, their potential as protective coatings. Products of silicone chemistry are normally applied as films on metal substrates in multi-layered patterns aimed at protecting these surfaces from environmental influences. In this work, several classes of protective coatings synthesized from a wide range of PDMS derivatives have been enlisted and discussed comparatively in terms of their barrier properties. The ease of modifications of these compounds in order to attain improved barrier properties have also been highlighted. More highlights on coating applications with functional materials incorporated with small molecules as well as those whose molecular chains are terminated with reactive organofunctional chemical groups, are also presented. This work is an attempt to comply protective applications of surface and pretreatment films made from PDMS, covering areas of anticorrosion, anti-biofouling, anti-icing, flame-resistance, self-cleaning as well as anti-reflection. The reasons for their unique protective abilities have been addressed for every chosen application, and the influences of precursor chemistries on the physical and chemical properties of resultant functional coating materials have also been discussed. This work also features polydimethylsiloxanes as potential risk of hazardous substances (RoHS) compliant additives in industrial coatings, and as reliable alternatives for chromate/tributyltin-loaded barrier films deployed in the field.

Green and Sustainable Technology for High-Efficiency and Low-Damage Manipulation of Densely Crosslinked Proteins.

A two-step technology using nontoxic and eco-friendly chemicals is developed for the durable setting of densely/highly crosslinked proteins, such as wool and hair. Currently, most technologies for morphological modification are effective only for materials from non-highly-crosslinked proteins and cellulose. Before their morphological change, only water is needed to interrupt hydrogen bonds and ionic linkages, which stabilize the relative positions of molecules in non-highly-crosslinked proteins and cellulose. However, highly crosslinked proteins contain disulfide crosslinks, which are insusceptible to water. Thus, the controlled cleavage of disulfide bonds is required for creating new morphologies of highly crosslinked protein materials, such as hair and wool. Herein, cysteine and citric acid (CA) were used for the two-step setting of highly crosslinked proteins. This recipe showed better morphological change and less mechanical loss than commercial hair styling products. A reaction between CA and keratin was proposed, and verified via NMR and Raman spectra and titration. This technology could be a prospective alternative to achieve durable hair setting, anticrease finishing of wool textiles, and other durable morphological changes needed for highly crosslinked proteins.

Preparation of Aqueous Dispersions of TEMPO-Oxidized Cellulose Nanofibrils with Various Metal Counterions and Their Super Deodorant Performances.

2,2,6,6-Tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibrils (TOCNs) with sodium carboxylate groups (TOCN-Na) were nanodispersed in water. The Na+ ions of TOCN-Na were exchanged with other monovalent, divalent, and trivalent metal (M) ions. When an aqueous metal acetate or AlCl3 solution was added to a 0.1% TOCN-Na/water dispersion or TOCN-COOH gel/water mixture under suitable conditions followed by sonication in water, individually nanodispersed TOCNs-M with divalent and trivalent metal counterions were obtained in yields of 24-87%. The amount of metal introduced into TOCN-M was approximately 20-50% of the TOCN carboxylate content when divalent and trivalent metal ions were used. These results indicate that intrafibrillar ionic linkages are selectively formed and these TOCN-M species nanodisperse at the individual nanofiber level without agglomeration in water. Filter papers with adsorbed TOCN-Cu/water and TOCN-Ag/water dispersions efficiently decomposed or adsorbed H2S and CH3SH gases, but filter papers containing fibrous TEMPO-oxidized celluloses with Ag+ or Cu2+ counterions had much lower gas-decomposition efficiencies.