Comparative Study on the Syntheses and Properties of Three N-lauroyl Aromatic Amino Acid Surfactants

Three N-lauroyl aromatic amino acid surfactants, namely, sodium N-lauroyl phenylalaninate (SLP), sodium N-lauroyl tyrosinate, and sodium N-lauroyl tryptophanate (SLTr), with aromatic group structures were synthesized via methyl ester method. Mass spectrometry, Fourier transform infrared spectroscopy, and nuclear magnetic resonance were applied for the structural representation of products. A comparative study of the three surfactants in terms of surface, foam, and emulsifying properties and decontamination performance was conducted. Results demonstrated that aromatic structure significantly influenced the properties of the three surfactants. SLTr had the best surface performance and foam property, whereas SLP had the best emulsifying property. All three surfactants exhibited strong decontamination effects on protein-soiled swatches.     

Rapid extraction of Cu(II) heavy metal from industrial waste water by using silver nanoparticles anchored with novel Schiff base

A new Schiff base named N-(4-hydroxy-3-methoxy benzylidine)-biphenyl-4-amine was synthesized from refluxing of equimolar quantity of vanillin and biphenyl-4-amine in alcoholic medium. Its composition, properties, and morphology were characterized by elemental analysis, FTIR (Fourier-transform infrared spectroscopy), UV–vis (ultraviolet visible spectroscopy), nuclear magnetic resonance spectroscopy, and mass spectral studies. Then, silver nanoparticles were synthesized by chemical reduction method and characterized by scanning electron microscope, UV–vis, FTIR, and mass spectra. The silver nanoparticles are then trapped with Schiff base by suitable method. The metal ion was analyzed by atomic absorption spectroscopy. Sugarcane bagasse (SCB) was used as solid phase for the removal of heavy metal from industrial waste water. Activation of solid phase was done with the base and acid, respectively. The Ag nano@Schiff base was adsorbed on the SCB. The effects of several parameters that affect the adsorption of Cu(II) metal ion including initial metal ion concentration, contact time, Schiff base weight, and pH were analyzed.     

Study on molecular structure and association behaviour of heavy subfractions of vacuum residue by an improved separation method

Vacuum residue (VR) is the most complex component of crude oil. Due to the special structure of heavy subfractions, physical aggregation and chemical coking reactions easily occur through molecular force, which affects the normal processing. Therefore, in-depth study and analysis of their composition, structure and association behaviours are particularly important. In view of the shortcomings of the traditional separation method in terms of separation accuracy, mainly including the purification of asphaltenes and the poor separation of resins. In this paper, a reasonably improved separation method is adopted, and the multi-stage asphaltene extraction and the multi-stage silica gel coupling separation are carried out innovatively, which achieves a high yield of 99% while ensuring the separation accuracy. The samples were characterized by elemental analysis (EA), gel permeation chromatography (GPC), Fourier-transform infrared spectroscopy (FT-IR), hydrogen nuclear magnetic resonance spectroscopy (¹H-NMR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and scanning electron microscope (SEM) to study their structural characteristics and association behaviours. The results show that the main forms of heteroatoms in asphaltene and resin surface are C-O-C, C-OH, pyridine, pyrrole, and thiophene, and the content of these substances is higher in asphaltene. Compared with resins, asphaltenes contain a more peri-condensed aromatic structure and shorter alkyl substituent side chains. By studying the hydrogen bond and acid–base interaction, it is found that asphaltene and resin mainly contain OH-OH, OH-π, and OH-ether O, of which the content of OH-OH is the highest. Asphaltene and resin have more neutral and basic substances. These hydrogen bonds and acid–base interactions caused by heteroatoms are the main forces for the association of the heavy subfractions of the VR.     

Monitoring the functionalization of single-walled carbon nanotubes with chitosan and folic acid by two-dimensional diffusion-ordered NMR spectroscopy

A conjugate between single-walled carbon nanotubes, chitosan and folic acid has been prepared. It was characterized by diffusion ordered two-dimensional hydrogen-1 nuclear magnetic resonance and hydrogen-1 nuclear magnetic resonance spectroscopy which revealed the presence of a conjugate that was generated by the linkage between the carboxyl moiety of the folic acid and the amino group of the chitosan, which in turn was non-covalently bound to the single-walled carbon nanotubes. The obtained diffusion coefficient values demonstrated that free folic acid diffused more rapidly than the folic acid conjugated to single-walled carbon nanotubes–chitosan. The values of the proton signal of hydrogen-1 nuclear magnetic resonance spectroscopy and two-dimensional hydrogen-1 nuclear magnetic resonance spectroscopy further confirmed that the folic acid was conjugated to the chitosan, wrapping the single-walled carbon nanotubes.     

Synthesis and Characterization of Polysiloxane Grafted Polyamide‐Amine Surfactants

Dendritic‐linear surfactants 1G PAMAM–Si and 2G PAMAM–Si were prepared by grafting the single epoxy terminated polydimethylsiloxane (SEPDMS) onto the 1G and 2G dendritic polyamide‐amine (PAMAM), respectively. SEPDMS was synthesized by hydrogen‐terminated polydimethylsiloxane and allyl glycidyl ether in chloroplatinic acid. The optimum grafting conditions were obtained by single‐factor experiments when the mole ratio of SEPDMS and PAMAM was 0.95:1, the reaction temperature was 60 °C, the reaction time was 5 h and the solvent percentage was 60%. The molecular structure of PAMAM–Si was characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, gel permeation chromatograph and potentiometric acid‐base titration. Furthermore, the stability, surface activity and emulsifying ability of the prepared surfactants were studied. The results showed that PAMAM–Si has high stability against dilution, acids, alkalies and salts. PAMAM–Si surfactants can significantly reduce the surface tension of water. And 2G PAMAM–Si is superior to 1G PAMAM–Si at the ability of emulsifying oil.     

Adsorption Behavior of Trimethylolpropane-Dehydroabietic Acid Ester at the Air–water Interface

A novel amphipathic trimethylolpropane-dehydroabietic acid ester was successfully prepared with acyl chloride method. Various analytical techniques such as liquid chromatography–mass spectrometry, Fourier transform infrared spectrometry, proton and carbon nuclear magnetic resonance spectroscopy were employed to evaluate the chemical structure of the ester. The surface properties of the ester were investigated by surface tension and resonance light-scattering techniques. The surfactant molecules are adsorbed at the water–air interface in different adsorption states, i.e., state 1 and 2. The dynamic adsorption behavior was studied by combining experimental results and a reorientation model. The molar fraction of solvent decreased, while the molar fraction of surfactant molecules increased with increasing ester concentration at the surface layer. The adsorption value of state 1 presented a unimodal shape and the adsorption value of state 2 presented an s-shape with the increase in surface pressure. The free energy of adsorption is ?36.06 kJ mol^?1, more negative than the free energy of micellization (?29.69 kJ mol^?1), it is actually easier for surfactant molecules to adsorb on the air–water interface.     

Synthesis and characterization of novel citric acid-based polyester elastomers

In this paper we report successful simple synthesis of unique elastic polyesters by carrying out catalyst-free polyesterification of multifunctional non-toxic monomers: 1,8-octanediol (OD), citric acid (CA) and sebacic acid (SA). The chemical, physical, and surface chemical properties of the resulting copolyester polyoctanediol citrate/sebacate [p(OCS)] have been investigated. This new material was characterized by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-ToF-MS), nuclear magnetic resonance spectroscopy (NMR), thermal analysis (TA), mechanical tests, photo-acoustic Fourier-transform infrared spectroscopy (PA-FTIR), X-ray photoelectron spectroscopy (XPS) and swelling experiments. We demonstrate that the chemical structure, morphology, physical integrity and surface chemistry of the synthesized co-polymer can be controlled by simply varying the initial acid concentration (CA/SA) in the pre-polymer. This novel p(OCS) polymer exhibits versatility in mechanical properties, hydration and hydrolytic degradation as determined by the chemical structure of the polyester elastomer.     

Acid−base properties of polyethylene composites with clays

We report on the surface energy characteristics of composite materials based on low‐density polyethylene with addition of bentonite and organic clay. Investigated were the surface free energy, its components and parameters by wetting methods according to Berger, spatial method, and method of nonlinear systems. The determined characteristics were carried out by the selective wetting conditions for the individual constituents of the composition, including the clay powder. The thermal, mechanical, and morphological properties of obtained composites were investigated. The possibility for predicting the surface properties of composite materials based on component‐wise analysis was demonstrated. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43629.     

Structural modification and characterization of lignosulfonate by a reaction in an alkaline medium for its incorporation into phenolic resins

We studied the enhancement of lignin reactivity in an alkaline medium, using sodium hydroxide in a microreactor set. The chemical composition and structural characterization of the reacted lignosulfonate in terms of the phenolic hydroxyl groups, aromatic protons, weight‐average molecular weight, number‐average molecular weight, and lignosulfonate content of all reacted lignins were determined. The techniques that we used were ultraviolet spectroscopy, proton nuclear magnetic resonance spectroscopy, and aqueous gel permeation chromatography. Using response surface methodology, we studied how the temperature and reaction time affected the lignin properties. The reaction conditions were temperatures between 116 and 180°C and reaction times between 18 and 103 min. Modeled response surfaces showed that the two factors affected the lignin properties within the studied ranges. The phenolic hydroxyl groups, aro matic protons, and lignosulfonate content increased when the severity of the treatment increased. The weight‐average molecular weight, number‐average molecular weight, and solid yield (%) decreased when the severity of the treatment increased. The reactivity of the modified lignins was studied with a formaldehyde reactivity test: more severe conditions produced greater improvements in the formaldehyde reactivity. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3286–3292, 2006     

Relevance of the acid–base approach in prediction of adhesion properties in two‐component injection moulding

We demonstrate the use of innovative wetting method in prediction of the adhesion properties of biobased polymers for two‐component injection moulding, taking into account the acid–base surface properties of joined materials. The measurements were carried out in accordance with modified Berger method by calculation of the difference in shortened acidity parameter ΔD_short between hard and soft component. Correlation factors up to 0.99 were observed between ΔD_short and peel force. In comparison to results obtained by conventional wetting methods, high potential for the selection of components with high interface adhesion and for prediction of the functionality by the acid–base approach was demonstrated. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43048.     

Photoaddition of fluoroolefins on aromatic polyamide

A photografting method has been developed to surface treat aromatic polyamide fabrics in the presence of fluoroolefin vapors. The new fabrics are more flame resistant in oxygen-enriched environment than untreated commercial aramid fabrics. The photoaddition reaction of haloolefins has been shown to irreversibly modify the fabrics, which were analyzed by water wettability, scanning electron microscopy, x-ray analysis, and ¹⁹F nuclear magnetic resonance spectroscopy.     

Polymer Surface Characterization: An Overview

The properties of a polymer surface can be decisive for the function of the polymer. Both in the assessment of existing polymer systems and the development of new ones the possiblity of characterizing the chemical composition and structure of the polymer surface becomes important. Various instruments and chemical methods used to characterize polymer surfaces and interfaces are reviewed. The pros and cons of electron spectroscopy for chemical analysis and derivatization schemes to enhance the detectability of functional groups, Fourier transform infrared spectroscopic methods (ATR, RIFT, PAS, micro), Raman spectroscopy, static secondary ion mass spectrometry, high resolution solid state nuclear magnetic resonance, microscopy and contact angle measurements are presented. The importance of the fact that the polymer surface can undergo comparatively rapid reorientations leading to a changed surface chemistry is discussed and exemplified.     

Organic–inorganic hybrid nanocomposites involving novolac resin and polyhedral oligomeric silsesquioxane

Octa(propylglycidyl ether) polyhedral oligomeric silsesquioxane (OpePOSS) was employed as a nanocrosslinker of novolac resin to prepare the organic–inorganic networks. The crosslinking reaction was investigated by means of Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy via model reaction. Thermal analyses indicate that the glass transition temperatures (T_g’s) and thermal stability of the organic–inorganic networks increased with increasing the content of POSS. Contact angle measurements show that the organic–inorganic nanocomposites displayed a significant enhancement in surface hydrophobicity as well as reduction in surface free energy. The improvement in surface properties was ascribed to the presence of POSS moiety in place of polar component of phenolic thermosets.     

A modified oil-soluble polyether used as multifunctional ashless additives with enhanced lubricating and corrosion protection performance

A novel oil soluble polyether derivative (OSPSA) was synthesized by the mono-esterification of oil soluble polyether (OSP) with succinic anhydride (SA). The product was characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance, gel permeation chromatography, thermogravimetry, and acid value. The friction test results indicate that OSPSA exhibited obvious improvement on the friction reduction (by 35.7%) and anti-wear performance (by 50.3%) comparing with the base oil. Additionally, OSPSA was also found to display excellent anticorrosion properties. OSPSA can be used as multifunctional ashless additive to provide excellent lubricity and corrosion protection properties. It can be speculated from the electrochemical experiments that the corrosion inhibition performance of OSPSA is mainly controlled by anode and the corrosion inhibition efficiency can reach 82.9%.     

Processing and characterization of elastomeric polycaprolactone triol–citrate coatings for biomedical applications

In this paper we describe the synthesis, processing and characterization of a novel elastic polyester coating created by carrying out catalyst-free polyesterification between biocompatible and non-toxic multifunctional reactants, namely polycaprolactone triol and citric acid. The physico-chemical and surface properties of the resulting polyester coatings and films have been investigated. This new material has been characterized by matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-ToF-MS), nuclear magnetic resonance spectroscopy (NMR), Fourier-transform infra-red spectroscopy (FTIR), water-in-air contact angle measurements, scanning electron microscopy (SEM), thermal analysis (DSC), mechanical tests and swelling experiments. The polymer structure, surface properties (morphology and chemistry), mechanical integrity and hydration of the elastomer can be controlled by simple variation of the initial citric acid concentration in the polymer formation. This feature of the novel polyester material presents a significant development in the production of advanced coatings for biomedical applications.     

High molecular weight poly(butylene terephthalate-co-butylene 2,5-furan dicarboxylate) copolyesters: From synthesis to thermomechanical and barrier properties

Poly(butylene terephthalate-co-butylene 2,5-furandicarboxylate) copolyesters (PBTFs) were synthesized from 1,4-butanediol, dimethyl terephthalate (DMT), and 2,5-furandicarboxylic acid (FDCA) by a two-step polymerization method. Their chemical structures were confirmed by Fourier-transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and carbon nuclear magnetic resonance before thermal properties were explored with differential scanning calorimeter and thermogravimetric analyzer. Results showed that PBTFs changed from semi-crystalline to completely amorphous when the content of FDCA unit was increased to 45 mol% at first, and then became crystallographic again with the further increment of FDCA unit to 75 mol%. For their mechanical properties, the tensile modulus and strength showed the similar trend, decreasing firstly and then increasing later. Their barrier to carbon dioxide and oxygen became better with the increasing of furan content due to the rigidity and higher polarity of furan ring. The performance of PBTFs copolyesters was investigated clearly, and the relative content of FDCA and DMT can be adjusted to satisfy different performance requirements.     

Poly(dimethylsiloxane‐b‐styrene) diblock copolymers prepared by reversible addition–fragmentation chain‐transfer polymerization: Synthesis and characterization

Well‐defined poly(dimethylsiloxane‐b‐styrene) diblock copolymers were prepared by reversible addition–fragmentation chain‐transfer (RAFT) polymerization. Monohydroxyl‐terminated polydimethylsiloxane was modified to form a functional polydimethylsiloxane/macro‐RAFT agent, which was reacted with styrene to form the diblock copolymers. The chemical compositions and structures of the copolymers were characterized by proton nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, and gel permeation chromatography. The surface properties and morphology of the copolymers were investigated with static water contact‐angle measurements, X‐ray photoelectron spectroscopy, transmission electron microscopy, and atomic force microscopy, which showed a low surface energy and microphase separation surfaces that were composed of hydrophobic domains from polydimethylsiloxane segments. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Regioselective carboxylation of aromatic compounds using cyclodextrin as mediator

The direct introduction of a carboxylic group into an aromatic carboxylic acid has been considered difficult theoretically. Recently, the regioselective syntheses of terephthalic acid, 4,4′-biphenyldicarboxylic acid and 2,6-naphthalene-dicarboxylic acid have been achieved by the carboxylation of benzoic acid, 4-biphenylcarboxylic acid and 2-naphthalenecarboxylic acid, respectively, with carbon tetrachloride and copper powder in aqueous alkali, using β-cyclodextrin (β-CyD) as mediator under mild conditions. The one-pot syntheses of terephthalic acid, 4,4′-biphenyldicarboxylic acid and 2,6-naphthalene-dicarboxylic acid have been attained by the carboxylation of benzene, biphenyl and naphthalene, respectively, with carbon tetrachloride and copper powder in aqueous alkali, using β-CyD as mediator. The essential factor of the carboxylation by the use of β-CyD is the inclusion complex formations of β-CyD with aromatic hydrocarbon, β-CyD with aromatic monocarboxylate and β-CyD with carbon tetrachloride, respectively, in the reaction mixture. The conformations of CyD–aromatic monocarboxylate inclusion complexes in aqueous alkali have been determined by the nuclear magnetic resonance spectroscopy using ¹H homonuclear Overhauser enhancement on the rotating frame. The high selectivity is ascribed to the conformation of the β-CyD–aromatic monocarboxylate inclusion complex. The reaction mechanism is discussed on the basis of inclusion complex formation.     

Apparent low‐field microwave absorption properties of styrene‐based copolymers containing acid groups

The microwave absorption properties of polystyrene (PS) copolymers containing sulfonic and methacrylic acid groups were investigated using an electron magnetic resonance spectroscopy method. It was found that, unlike PS and poly(methyl methacrylate) homopolymers, the acid groups containing PS copolymers showed three electromagnetic resonance signals at 3250, 3035, and 520 G; the first and last two signals were thought to be due to the presence of anion radicals and acid groups in PS, respectively. This result indicated that the PS copolymers exhibited magnetic field dependent low‐field microwave absorption behavior. This also suggested that the low‐field microwave absorption required the presence of both the aromatic and acidic groups in the materials. To explain both the low‐field absorption and magnetic field dependence, we proposed a coupled mechanism including both the magnetoplasticity associated with a plastic deformation and the rotational degree of freedom of aromatic groups containing electric dipoles with natural spin defects. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Cationic polymerization of β-pinene and styrene

The yield, composition, and molecular weight of homopolymers and copolymers of β-pinene and styrene are described as a function of the feed, temperature, and solvent. Fractionation, gel permeation chromatography, and nuclear magnetic resonance spectroscopy of GPC fractions are used as analytical tools to present evidence for copolymerization in methylene dichloride. Additional support for copolymerization is obtained from the relation of polymer composition to percent conversion. The reduction of molecular weights of homopolymers by aromatic solvents was investigated.