Infrared spectroscopic, X-ray powder diffraction, diffuse reflectance, and electron-spin resonance examination of homoionic bentonite from Sardinia treated with diazomethane indicates that poly-methylene was formed in the interlayer position. Polymerization can be attributed to the acidic properties of the residual water in the interlamellar space, depending on the nature of the exchanged ion. The presence of an interlayer polymer causes the clay to assume strong hydrophobic properties.

One-aminonaphthalene is sorbed onto the Na-saturated smectite clays, montmorillonite and hectorite, by cation exchange. In the presence of Fe3+, either in the clay structure or on the clay surface, sorption is followed by the formation of a blue-colored complex, with the continuous disappearance of aminonaphthalene from solution and the clay surface. The rate of aminonaphthalene disappearance decreases as pH increases. With time, four major products that appear to be structural isomers of N(4-aminonaphthyl)-l-naphthylamine are produced. A simplified model of this transformation is suggested to be the oxidation by Fe3+ of sorbed aminonaphthalene forming a radical cation-clay complex. A subsequent reaction between the radical-cation and a neutral aminonaphthalene molecule takes place, with the products being strongly sorbed to the clay surface.

The adsorption and reaction of thiophene and methylthiophenes in the interlayer of Cu2+- and Fe3+-montmorillonites were investigated by resonance Raman spectroscopy. Thiophene and 3-methylthiophene polymerized to form cations of polythiophene and polymethylthiophene respectively, which were characterized by absorption bands in the near-infrared region. These polymer cations formed in the interlayer were reduced to their neutral polymers if the clay-polymer complexes were in contact with water, and the formation of their neutral polymers was clearly demonstrated by their resonance Raman spectra. 2,5-Dimethylthiophene in which polymerization was hindered by methyl substitution at the 2 and 5 positions, was oxidized to 2,5-dimethylthiophene cation in the interlayer.

Air-dried samples of homoionic Na-, Ca-, Al-, and Fe-smectite were equilibrated with 2,6-dimethylphenol vapor for 24 hr. Infrared spectra of the complexes formed indicated that a portion of the sorbed phenol was transformed into quinone-type compounds. Both sorption and transformation were greatly influenced by the nature of the exchangeable cation and followed the order Fe ≫ Al > Ca > Na. Changes in the electron spin resonance spectra of the clays following interaction with the phenol followed the same order, indicating that these reactions are enhanced by a transition metal cation, such as Fe3+, on the exchange complex. The reaction products from the clay complexes were extracted with methanol and identified using ultraviolet/visible spectrophotometry, high-pressure liquid chromatography (HPLC), and mass spectrometry. The extracts contained mixtures of products including the parent phenol, di-, tri-, and tetramers of the phenol, as well as quinone and quinone dimers. The identities of these compounds were further confirmed by the coincidence of the retention times of HPLC peaks obtained from extracts of the clays with those from compounds produced by oxidation of 2,6-dimethylphenol with Ag2O.

Reactions of smectite with phenols were investigated to understand the role of clay minerals in abating transport of these organic pollutants to ground water. Sorption of o-methylphenol, o-chlorophenol, and m-methylphenol by the clay with different exchange cations was accomplished by passing phenol vapors in a slow stream of air or nitrogen through the samples. The resulting products, extracted with methanol and analyzed by using mass spectrometry, included monomers, dimers, trimers, and tetramers of the parent phenol and of the corresponding quinones, the oxidation product of the phenols. In extracts from the Fe-clay-phenol complexes formed in air, traces of the phenolic pentamers were also detected. Both sorption and polymerization were much higher in air than in nitrogen. The greatly reduced polymerization in nitrogen suggests that anaerobic environment of the landfill sites may facilitate phenol transport to ground water. The degree of polymerization and its magnitude was in the order Fe- > Al- > Ca- > Na-clay.

A kaolinite-polymer intercalation complex was apparently formed for the first time by the polymerization of acrylonitrile between the kaolinite layers. A kaolinite-ammonium acetate intercalation complex was dispersed in acrylonitrile monomer. The monomer was apparently incorporated between the layers by displacing intercalated ammonium acetate. After the removal of excess monomer, the intercalation complex was heated to cause polymerization. The resulting kaolinite-polyacrylonitrile (PAN) intercalate showed a basal spacing of ∼ 13–14 Å. On heating the complex at 220°C for 1 hr in air, the spacing decreased slightly. The hydrogen bond between the hydroxyls of kaolinite and probably the C≡N group of PAN was not affected after heating at 220°C. Even after heating at 400°C, the layers expanded. Because the starting kaolinite-ammonium acetate intercalation complex decomposed at a much lower temperature, these observations strongly suggest the presence of PAN between the layers.

The effect of ethylene oxide-sterilization on homoionic (Na+, K+, Ca2+, Cu2+, Al3+, and Fe3+) montmorillonite samples was examined. The results indicate that ethylene oxide polymerized to polyethylene glycol in the interlayer of Cu2+-, Al3+-, and Fe3+-saturated clays, as substantiated by the increase in the d(001) values, as well as by the decrease in the cation-exchange capacity after reaction. On the contrary, ethylene oxide failed to react in the presence of the Na+-, K+-, and Ca2+-clays, likely due to the lower acidity of the exchange cations.

Acrylamide has been polymerized between the layers of kaolinite by heat treatment. Acrylamide monomer was first intercalated by the displacement reaction between a kaolinite-N-methylformamide (NMF) intercalation compound and a 10% acrylamide aqueous solution. The resulting intercalation compound showed a basal spacing of 11.3 Å. Infrared (IR) spectroscopy and 13C nuclear magnetic resonance spectroscopy with cross polarization and magic angle spinning (13C CP/MAS-NMR) indicated the replacement of NMF by acrylamide. IR spectroscopy also showed the formation of hydrogen bonds with the hydroxyls of kaolinite. When the kaolinite-acrylamide intercalation compound was heated at 300°C for 1 hr, the basal spacing increased to 11.4 Å, and IR and 13C CP/MAS-NMR showed the disappearance of C=C bonds, indicating the polymerization of acrylamide. The heat-treated kaolinite-acrylamide intercalation compound was resistant to 30 min-washing with water, whereas the untreated kaolinite-acrylamide intercalation compound collapsed after the same treatment, an observation consistent with acrylamide polymerization between the layers of kaolinite. IR spectroscopy revealed that polyacrylamide was hydrogen bonded to kaolinite, but in a manner different from the hydrogen bonding of acrylamide.

The adsorption of olefins at 25 °C in gas- or vapor-solid systems on 4 clays dried at 120 °C was studied by infrared spectroscopy. Products of condensation have the spectra of paraffinic oligomers. Paraffins are adsorbed onto the same structural surface hydroxyls that adsorb olefins, confirming the physical unspecific character of this adsorption. These hydroxyls do not participate in the condensation reaction. The reappearance of these hydroxyl bands after evacuation suggests that product molecules are not adsorbed onto the surface but remain on it because of its low vapor pressure. The reversible adsorption sites participate in feeding the condensation sites. Double-bond isomerization of olefins was not observed, at room temperature, on clays, alumina and silicas dried at 120 °C. When the gas-phase is evacuated or swept with inert gas, reaction does not proceed with a new monomer. Paraffins are only physically adsorbed.

Products resulting from the reaction of toluene with Cu(II)-montmorillonite were analyzed using GC/MS, HPLC/MS, GPC, and FTIR methods. Numerous oligomers of toluene were observed, extending at least as high as the resolution limit (1500 g/mol) of the GPC column. The FTIR spectrum of the nonvolatile components of the extract was very similar to that of liquid toluene. GC/MS data on the volatile components revealed dimers, trimers, and a multitude of transmethylated products. Oligomerization proceeded via both ring-ring (i.e., polyphenyl) and ring-methyl linkages. The primary trans-methylated products were tert-butylbenzene and isopropylxylene, indicating a competition between ringand side-chain methylations. The side-chain substitutions cannot be explained in terms of the aromatic radical cation intermediate which typically forms in arene/clay reactions. A consideration of alkylbenzene reactions observed in various other media suggests that the present transmethylation reactions occur via a benzyl cation intermediate.

The objective of this study was to determine whether smectites abiotically catalyze transformation of glucose under conditions relevant to soil organic matter (SOM) formation. Four smectites saturated with Na, Ca, Fe and Al were incubated under abiotic conditions with glucose solutions for 21 days at 37°C. After the incubations, soluble organic C recoveries ranged from 95 to 109.3%, relative to the amount of C added as glucose; however, glucose recoveries in the solutions ranged from 18.3 to 98.3%. The results indicate that a significant amount of the added glucose was abiotically transformed to soluble organic compounds other than glucose during the incubations. In general, glucose recoveries decreased with the acidic character of smectites: SWa-1 > Panther > Otay. Also, within clays, glucose recoveries decreased as the exchangeable cation became more acidic: Na > Ca > Al. Higher glucose recoveries were obtained for ‘Fe-rich’ smectites relative to ‘Fe-poor’ smectites, suggesting that Fe-oxyhydroxy coatings on smectite surfaces inhibit the transformation of glucose. High-pressure liquid chromatography analysis of the incubation solutions revealed small peaks for 5-(hydroxymethyl)-2-furaldehyde along with peaks for other unknown compounds. The results suggest that under conditions similar to those found in soils, smectites catalyze glucose dehydration to form furfural compounds. Polymerization of furfural compounds may be a major pathway leading to the formation of new humic materials in soils.

Injection of CaCl2 and Na2SiO3 solutions into clay suspensions during electroosmosis often improves the cohesive strength of clays near the anode and cathode, whereas the cohesive strength of clays between the electrodes remains weak. Although the main improvement mechanism for the cohesive strength of clays near the cathode was demonstrated to be a pozzolanic reaction (formation of calcium silicate hydrate cement), the mechanism of improved cohesive strength near the anode is still not understood. The objective of the present study was to investigate the mechanism for the improvement of cohesive strength near the anode and, thus, make it possible to determine a way to enhance the range in improvement using kaolinite as the test clay. The test was performed by first injecting CaCl2 solution during electroosmosis until the optimum volume of CaCl2 was attained. This was followed by treatment with Na2SiO3 solution for different lengths of time. The results indicate that the anode region after treatment was acidic (pH = 4) because the electrolysis of water causes acidification near the anode. As Na2SiO3 solution was injected through the anode, the mechanism of cohesive strength improvement of the treated clay near the anode was attributed to the silicic acid polymerization effect provided by the Na2SiO3 solution. The silicic acid may link the clay particles together to form a gel network in a low pH environment. The clay gel network structure developed rigidity as the water content was reduced. In addition, as the volume of injected Na2SiO3 solution was increased, the cohesive strength near the anode also increased.

Numerous studies have investigated the ligand-promoted dissolution of Fe (oxyhydr)oxides. In natural environments, inorganic ligands can compete with organic ligands for surface sites on (oxyhydr)oxides which may influence dissolution rates. Published research of this interaction and its effect on the dissolution of (oxyhydr)oxides is rare. The objective of the present study was to examine the extent to which silica, as a naturally occurring competitive ligand added in the form of silicic acid, impacts the oxalate-promoted dissolution of the common soil Fe (oxyhydr)oxide goethite. Sorbed silica reduced the oxalate-promoted dissolution rate of goethite at all surface coverages investigated. As initial silica solution concentrations increased from 0.50 mM to 5.0 mM, relatively little change in the dissolution rate was observed. Fourier-transform infrared (FTIR) spectra indicated that, as silica-surface coverages increased, the silica underwent polymerization on the goethite surface. Initially, silicate was associated with surface functional groups, but as polymerization occurred some of the silica appeared to desorb from the goethite surface without being released into the bulk solution, suggesting that silica polymers formed discrete islands or surface clusters that grew away from the goethite surface rather than expanding epitaxially across the surface. Minimal changes were observed in the quantity of reactive goethite surface, which is responsible for the observed dissolution rates, as silica-surface coverages increased.

Hydroxy-interlayered minerals (HIMs) are typical of moderately acidic soils. Barnhisel and Bertsch (1989) defined the hydroxy-interlayered clay minerals as a solid-solution series between smectite, vermiculite and pedogenic or aluminous chlorite end-members. Their experimental data for the relationship between the decrease in cation exchange capacity (CEC) and the amount of Al fixed in the interlayers of smectites and vermiculites is reinterpreted using calculated structural, chemical and X-ray diffraction (XRD) evidence. The adsorbed Al ions are in a 6-fold coordination state: [Al(OH)x(H2O)y](3−x)+ with x+y = 6. The polymerization process occurs before saturation of the exchange sites by Al ions. Some of the adsorbed Al ions form polynuclear cations keeping a constant positive charge.

X-ray diffraction patterns of oriented preparations in the ethylene glycol-solvated state suggest that HIMs consist of randomly interstratified expandable and chlorite-like layers (17 and 14.2 Å). Chlorite-like layers result from the selective adsorption of Al complex ions in specific interlayer zones that behave similarly to Al-chlorite (donbassite-like) with incomplete (60%) ‘gibbsite-like’ sheets (chlorite60). Using this framework, HIM XRD patterns can be interpreted by comparison with calculated chlorite60-dismectite mixed-layer mineral patternss using the NEWMOD software.

Enzymes can be a renewable source of catalytic agents and thus be interesting for sustainable approaches to create and modify functional materials. Here, thin hydrogel layers were prepared as thin coatings on hard substrates by immobilized horseradish peroxidase. Hydrophilic 4-arm star shaped telechelics from oligo(ethylene glycol) bearing on average 55% end groups derived from aromatic amino acids served as monomers and enzymatic substrates. Shifts of the contact angle from 84° to 62° for the wetting process and of zeta potential towards the neutral range illustrated an alteration of physicochemical properties of the model surfaces by a hydrophilic shielding. Time-of-flight secondary ion mass spectrometry (ToF-SIMS), quartz crystal microbalance and atomic force microscopy (AFM) experiments enabled the qualitative and quantitative proof of hydrogel deposition at the interface with thicknesses in the medium nanometer size range. Conceptually, as the immobilized enzyme becomes entrapped in the hydrogel and the crosslinking mechanism bases on a radical reaction after enzymatic activation of the monomers with a limited diffusivity and lifetime, the formed network material can be assumed to be inhomogeneous on the molecular level. On the macroscale, however, relative homogeneity of the coating was observed via ToF-SIMS and AFM mapping. As an exemplary functional evaluation in view of bioanalytical applications, the thrombogenicity of the coating was studied in static tests with human blood from several donors. In the future, this “coating-from” approach may be explored for cell culture substrate coatings, for protein/biofilm repellence in technical applications, or in bioanalytical devices.

The polymerization of 3,4-ethylenedioxythiophene (EDOT) onto nanosilica (SiO2) was synthesized in this study by using supercritical carbon dioxide (SCCO2). With the addition of dopants of p-toluenesulfonic acid (p-TSA) or decylbenzene sulfonic acid (DBSA), the PEDOT/SiO2 composite became conductive. The product was characterized by FTIR spectroscopy and the core-shell structure was confirmed through the TEM images. The electrical properties were analyzed by UV-vis absorbance and four-point probe measurement. DBSA is shown as the better dopants with the molar ratio (DBSA/EDOT) of 0.2 at the reaction time of 48 hours. The maximum coating percentage is 63 wt% under the optimal operation conditions at 40oC and 280 bar. The conductivity is tuned up to 6.6×10-2 S/cm after the coating process.

Nanocomposite hydrogels of poly-n-isopropyl were prepared by incorporating gold and magnetite nanoparticles. The nanocomposite-based hydrogels formed were geometrical, ∼7.3 mm in diameter and 5 mm thick (in the swollen state). Morphological analysis was characterized by a scanning electron microscope. Drug-loaded hydrogels were subjected to laser heating at 1 W, 1.5 W and 2 W for 20 min in each laser cycle. The metabolic activities of the cells were analysed. The photothermal conversion efficiency of the nanocomposite hydrogels was also evaluated for P(NIPA)-AuNP-PG and P(NIPA)-MNP-PG to be 36.93 and 32.57 %, respectively. The result was then discussed for potential applications whereby metal-based hydrogels can be employed in microfluidic devices for targeted cancer drug delivery.

Functional polymers were previously employed to minimize the susceptibility of metallic nanoparticles (MNPs) for aggregation. Herein, we intended to conjugate catechol moiety into the polymer chain end considering its anchoring ability to virtually most surfaces. Accordingly, catechol end-functionalized polysarcosine (cat-PSar) was successfully prepared from the ring-opening polymerization (ROP) of sarcosine N-carboxyanhydrides (Sar-NCA) using dopamine hydrochloride initiator. ROP of Sar-NCA was carried out at different monomer to initiator feed ratios. The molecular structure of cat-PSar was confirmed by 1H NMR and MALDITOF. Afterward, the obtained catechol functionalized polymer was used for in-situ synthesis and stabilization of silver nanoparticles (Ag-NPs) in aqueous solution. The observed characteristic absorption peak at λmax of 415 nm indicates the formation of Ag-NPs. Scanning electron microscope (SEM) images also elucidate the formation of Ag-NPs with the relatively small sizes of the nanocomposite at a high concentration of silver nitrate. Hence, biomimetic polymers could play a dual role as reducing and stabilizing agents in the preparation of monodispersed MNPs.

In this contribution, we devoted ourselves to fabricating aggregation-induced emission (AIE) activity copolymers via one-pot combination of RAFT polymerization and Biginelli reaction for the first time. When the feeding ratio of TPB was 33.5%, the molar fraction of TPB was, respectively, about 14.2 and 22.5% in PEG-PTE1 copolymers by two-step strategy and PEG-PTE2 copolymers by one-pot strategy with the similar structure. The Mn of PEG-PTE1 increased to 59,300 from 52,800 of PEG-AE presoma with narrow PDI, which was more than Mn of PEG-PTE2 with 52,300. As compared with PEG-PTE2, when the feeding ratio of TPB was 48.6%, the molar fraction of TPB increased to 32.6% in PEG-PTE3. In aqueous solution, the as-obtained PEG-PTE2 copolymers can self-assemble into fluorescent organic nanoparticles (FONs) with 100–180 nm spherical morphology, the maximal emission peak of which presented at 460 nm with the obvious AIE phenomenon. Moreover, due to the low toxicity and excellent cell dyeing behavior, the as-prepared PEG-PTE2 copolymers displayed great potential for biomedical applications.

The kinetics of silica polymerization was measured in silicic acid solutions containing a suite of 0.1 M amino acids, 0.1 M citric acid, 0.7 M NaCl, and 0.10 M NaCl (Control). Fitting a modified classical rate model to measurements of induction time (τ) at 20 °C for a series of supersaturated solutions, we estimate the thermodynamic barrier (ΔGc), interfacial free energy (γ), and kinetic barrier (Δagk) for silica nucleation. For 0.10 M NaCl solutions, γControl = 54.9 ± 1.6 mJ/m2 and ΔagkControl = 2.29 × 10−19 J/mol. These values are consistent with previous reports for amorphous and fused silica materials. To facilitate comparisons with the treatments, ΔagkControl is converted to a molar basis and used as a reference datum, such that ΔagkControl = 0.0 J/mol. The effects of salt and organic acids on nucleation rate have thermodynamic and kinetic origins, respectively. Faster nucleation rates measured in 0.7 M NaCl solutions arise from a lower interfacial free energy, such that γ0.7 M NaCl = 51.4 ± 1.7 mJ/m2. Organic acids increase rate through biomolecule-specific reductions in Δagk. Catalytic effects are greatest for lysine (Δagklysine = −1685 ± 315) and citric acid (Δagkcitric = −1690 ± 96 J/mol). Reductions in the kinetic barrier correlate with net positive charge of the amino acids and dissociation of the amine $\left( {{K_{\alpha {\rm{ ‐ N}}{{\rm{H}}_3}^ {\bf{+}} }}} \right)$ group and thus the abundance of the conjugate base. Citric acid, lacking amine groups, promotes the greatest rate enhancement, thus demonstrating the role(s) of additional kinetic factors in promoting nucleation rate. Catalytic activity correlates with multiple physical and chemical properties of the organic acids.