Synthesis,characterization, and application of metal-free sulfonamide-vitamin C adduct to improve the optical properties of PVA polymer

Improving optical properties is an important topic in the field of polymer science. In this research, a novel, metal-free, and inexpensive vitamin C sulfonamide adduct has been developed to enhance the optical behaviors of polyvinyl alcohol (PVA). Initially, the vitamin C adduct has been fabricated through atom economic reaction and then characterized using several spectroscopic techniques, including ¹H NMR, ¹³C NMR, DEPT-135, Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). Accordingly, a dramatic chemical alteration in ascorbic acid structure has been confirmed and led to enhancing chemical interactions with the host polymer. The ascorbic acid adduct has been doped into PVA to prepare a flexible film of polymer composites with potential optical behaviors. The identity of composite film has specified from FTIR, XRD, and UV–vis spectroscopy. The XRD pattern of the hybrid polymer has revealed a remarkable boost in its amorphous structure compared to the PVA host. The FTIR data of both matrix PVA and its composites reveal the potent chemical interactions of functional groups within the hybrid PVA. The main optical information of synthesized hybrid film was obtained from the UV–vis spectra. The refractive index (n) and dielectric loss (ε_i) values are elevated notably, whereas the optical band gap energy (E_g) declined from 6.3 to 3.6 eV. The direct electronic transition between the valence band (VB) and conduction band (CB) was determined by implementing Tauc’s model. These preliminary results suggest that the fabricated flexible composite will have an excellent opportunity to use in the manufacturing optical devices.     

Facile and green methodology for surface‐grafted Al2O3 nanoparticles with biocompatible molecules: preparation of the poly(vinyl alcohol)@poly(vinyl pyrrolidone) nanocomposites

The present work describes preparation of modified alumina with biocompatible, water soluble, and treating agents such as citric acid and ascorbic acid. Also, the influence of the modified nanoparticles (NPs) into the blend of poly(vinyl alcohol)@poly(vinyl pyrrolidone) (50/50) matrix was studied. At first, citric acid and ascorbic acid as environmental friendly agents were grafted on the surface of Al₂O₃ NPs. Then, nanocomposites (NCs) with different amounts of modified Al₂O₃ NPs were prepared via a simple ultrasonic method. The characterizations of the molecular structure of the NCs specified that chemical and physical interactions happened between inorganic and organic counterparts. The mutual effect of modified NPs into the polymer matrix was investigated on the structural, interfacial interaction, thermal stability, and optical properties. The results from morphological characterization confirmed changes in morphology of poly(vinyl alcohol) and poly(vinyl pyrrolidone) after loading NPs. Uniform dispersion of modified spherical Al₂O₃ NPs powders into the matrix of 50/50 polymers was detected by field emission scanning electron microscopy and energy‐dispersive X‐ray. Adding M‐NPs into the polymer matrix expressively improved the thermal stability of NCs. Peaks in ultraviolet–visible spectra were shifted to the higher absorption. Copyright © 2017 John Wiley & Sons, Ltd.     

Seed‐Mediated Synthesis of Single‐Crystal Gold Nanospheres with Controlled Diameters in the Range 5–30 nm and their Self‐Assembly upon Dilution

Single‐crystal gold nanospheres with controlled diameters in the range 5–30 nm were synthesized by using a facile approach that was based on successive seed‐mediated growth. The key to the success of this synthesis was the use of hexadecyltrimethylammonium chloride (CTAC) as a capping agent and a large excess of ascorbic acid as a reductant to ensure fast reduction and, thus, single crystallinity and a spherical shape of the resultant nanoparticles. The diameters of the gold nanospheres could be readily controlled by varying the amount of seeds that were introduced into the reaction system. The gold nanospheres could be produced with uniform diameters of up to 30 nm; thus, their localized surface plasmon resonance properties could be directly compared with the results that were obtained from theoretical calculations. Interestingly, we also found that these gold nanospheres self‐assembled into dimers, larger aggregates, and wavy nanowires when they were collected by centrifugation, dispersed in deionized water, and then diluted to different volumes with deionized water.     

One-pot surfactantless route to polyaniline hollow nanospheres with incontinuous multicavities and application for the removal of lead ions from water

Polyaniline (PANI) hollow nanospheres with controllable incontinuous nanocavities ranging in size from 10 to 50 nm as a novel hollow nanostructure have been successfully fabricated by chemical polymerization of aniline with chloroaurate acid as the oxidant and citric acid as the doping acid. Experimental factors, such as concentration and kind of oxidant and doping acid, were investigated to illustrate their effect on morphology of PANI. According to experimental results and time-dependent investigations, a possible formation mechanism involved was then proposed. The adaptability of this route to hollow nanostructures with multicavities of other conducting polymer was also revealed. Furthermore, the adsorption properties of PANI hollow nanospheres toward lead ions in water were investigated.     

Cover Picture

The cover picture shows an etched and metallized optical fiber tip for chemical analysis on the nanometer scale using near-field optical microscopy and spectroscopy. The background shows an image of nanospheres embedded in a polymer matrix that were visualized via fluorescence. Further details are given in the review by R. Zenobi and V. Deckert on pages 1746-1756.     

Spectroscopic analysis of triflusal impregnated into PMMA from supercritical CO2 solution

The applicability of supercritical carbon dioxide (scCO₂) as a solvent instead of organics has already been demonstrated for the impregnation of biopolymers with pharmaceuticals. This specific process enables the dispersion of a drug in a polymer and leads to further control of drug release. In this work, scCO₂ technology was employed to impregnate triflusal active agent and its hydrolysis metabolite 4-(trifluoromethyl) salicylic acid (HTB) into PMMA bars. Confocal Raman spectroscopy and high-pressure liquid chromatography were the main analysis techniques employed to characterize the degree of dispersion of the drug inside of the polymer. In the Raman analysis, obtained spectra were decomposed with several Gaussians functions. Hence, by using the decomposition of each spectrum it was possible to study the evolution of the concentration of the drug and its metabolite in hundreds of different positions along the radius of the polymer bar. Raman spectroscopy was also used to detect water in the PMMA matrix and to analyze its influence in the formation of the HTB. Finally, spectroscopic analysis showed that scCO₂ impregnation process resulted in triflusal and its metabolite being molecularly dispersed in the polymer matrix. Drug molecules interaction with PMMA chains was detected for the metabolite HTB, but not for triflusal.     

制备核-壳结构聚合物纳米微球和空心球的原位聚合方法的普适性研究

采用原位聚合制备核-壳结构聚合物纳米微球和空心球的新方法, 利用甲基丙烯酸2-羟丙酯(HPMA)和乙酸乙烯酯(VAc)两种单体, 在类似的反应条件下, 成功地制备了以聚(ε-己内酯)(PCL)为核, 分别以交联PHPMA和PVAc为壳的纳米微球; 将微球的核酶解后, 分别得到了对应的交联PMAA空心球和交联PVA空心球. 结果表明, 原位聚合制备核-壳结构聚合物微球的新方法具有一定的普适性, 适用于单体可溶于水而生成的聚合物不溶于水的体系.     

Evaluation of Polyvinyl Acetate for Food Packaging by Studying Interactions Using HPLC

Abstract

Polyvinyl acetate was evaluated for food packaging by studying interactions with food nutrients like ascorbic acid, niacin, phenylalanine and caffeine. The polymer was immobilized on silica support and food based solvent like water used as a mobile phase. Thermodynamic parameters such as enthalpy of sorption, Gibb's free energy and activity coefficient data were used to determine mechanism, magnitude and kind (weak or strong) of interactions. Possibility of migration of the nutrients into the polymer and its suitability as a packaging matrix was concluded from the activity coefficient values.     

Fe3O4/Polypyrrole/Au nanocomposites with core/shell/shell structure: synthesis, characterization, and their electrochemical properties

Uniform Fe3O4 nanospheres with a diameter of 100 nm were rapidly prepared using a microwave solvothermal method. Then Fe304/polypyrrole (PPy) composite nanospheres with well-defined core/shell structures were obtained through chemical oxidative polymerization of pyrrole in the presence of Fe3O4; the average thickness of the coating shell was about 25 nm. Furthermore, by means of electrostatic interactions, plentiful gold nanoparticles with a diameter of 15 nm were assembled on the surface of Fe3O4/PPy to get Fe3O4/PPy/Au core/shell/shell structure. The morphology, structure, and composition of the products were characterized by transmission electronic microscopy (TEM), scanning electronic microscopy (SEM), X-ray powder diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy. The resultant nanocomposites not only have the magnetism of Fe3O4 nanoparticles that make the nanocomposites easily controlled by an external magnetic field but also have the good conductivity and excellent electrochemical and catalytic properties of PPy and Au nanoparticles. Furthermore, the nanocomposites showed excellent electrocatalytic activities to biospecies such as ascorbic acid (AA).     

中性溶液中抗坏血酸在六氰合亚铁酸钴铜膜修饰铂电极上现场红外光谱电化学研究

抗坏血酸 ( AA)是生物化学和生物医学中的一种重要生理物质 ,因而在电催化和电化学传感器领域得到了广泛的研究 .对抗坏血酸的研究主要集中在两个方面 :一方面是研究 AA在各种电极上的电氧化机理、动力学参数及电催化机理 [1,2 ] ;另一方面是为了监测各种生物化学和生物医学中 AA的浓度发展起来的 AA传感器 .利用碳电极的各种预处理方法 [3,4 ]以及利用各种化学修饰电极 [5,6 ]来促进AA的电氧化动力学过程及解决 AA与各种共存物如多巴胺及脲酸等之间的相互干扰问题 .六氰合亚铁酸钴铜修饰电极 ( Co Cu HCF/Pt) [7] 在中性溶液中十分…     

In situ gel forming graft copolymers of a polyaspartamide and polylactic acid: Preparation and characterization

In situ gel forming systems have been prepared by linking polylactic acid (PLA) to a water soluble and polyfunctional polymer, such as α,β-poly(N-2-hydroxyethyl)-d,l-aspartamide (PHEA). Three graft copolymers PHEA-PLA with a different derivatization degree in PLA, have been synthesized and characterized. PHEA-PLA graft copolymer with the highest amount in PLA has been used to prepare solutions in organic solvents able to give rise to gel-like matrices when injected into phosphate buffered saline solution. The chemical degradation of these gels has been evaluated and in vitro tests have been performed to evaluate the cell compatibility of the hydrolysis products. The possibility to use these gels for drug release has been investigated by incorporating leuprolide as a peptide model drug and by evaluating its in vitro release. To improve the drug release profile, PHEA-PLA graft copolymer has been derivatized with pendant carboxylic groups that are able to form an ion pair with the leuprolide thus reducing the burst effect and prolonging its release.     

Chemical and structural modification of polymers by matrix polymerization

The condensation polymerization of urea and formaldehyde in water in the presence of a macromolecular matrix, polyacrylic acid, as well as properties of composites obtained by the matrix polymerization, have been studied. The chemical structure of the urea-formaldehyde polymer was changed by the presence of the matrix. The products of matrix polymerization are composites consisting of a stoichiometric polycomplex of polyacrylic acid with the urea-formaldehyde polymer and an excess of one of the components, depending on the initial composition of the system. Introduction of matrix macromolecules into the reacting system leads to a fibrillized structure of the urea-formaldehyde polymer. The polycomplex, as well as composites with high content of polyacrylic acid, are glasses characterized by high compressive strength and ability to forced elastic deformation. They swell in water. The highly cooperative character of potentiometric titration curves for swollen gels and the quantitative yield in intermolecular amidation indicate an ideal structure of the polycomplex stabilized by hydrogen and ionic-type bonds.     

Fabrication of polymer hollow nanospheres by a swelling–evaporation strategy

A general route, involving swelling–evaporation processes, is proposed for the generation of polymer hollow nanospheres derived from polymer nanoparticles for the first time. Different swelling reagents, such as ethanol, o‐toluidine, toluene, and carbon tetrachloride, have been used to study their effect on the morphology of the resultant polymer hollow structures. The evaporation conditions, such as the temperature and pressure, can be used to tune the size and shell thickness of the polymer hollow structures. The chemical structures of the polymer have been characterized with X‐ray diffraction, Fourier transform infrared, and ultraviolet–visible spectroscopy. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2638–2645, 2007     

Preparation of thermoresponsive and pH-sensitivity polymer magnetic hydrogel nanospheres as anticancer drug carriers

In this work, a novel thermo and pH responsive magnetic hydrogel nanosphere poly(N-isopropylacrylamide-co-acrylic acid)/Fe(3)O(4) (poly(NIPAAm-co-AA)/Fe(3)O(4)) has been successfully prepared. The magnetic hydrogel nanospheres with thermo and pH-sensitivity were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), Fourier transform infrared-spectrometer (FT-IR), UV-vis absorption spectroscopy, and vibrating sample magnetometer (VSM). The magnetic hydrogel nanospheres exhibited uniform sphere structures and superparamagnetic property. Finally, the drug loading capacities and the releasing behavior of the magnetic hydrogel nanospheres were investigated with doxorubicin hydrochloride (DOX) as an anticancer drug model. The resulting magnetic hydrogel nanospheres exhibited high encapsulation efficiency (95%) to DOX under an appropriate condition. In vitro release experiments revealed that release was faster at pH 5.3 (37°C) than at pH 7.4 (25°C) or pH 7.4 (37°C). The DOX-loaded magnetic hydrogel nanospheres also showed enhanced anticancer effect compared with the free drug in vitro. These presented results suggested that the magnetic hydrogel nanospheres have a potential as tumor targeting drug carrier.     

Surface-enhanced Raman scattering of EDOT and PEDOT on silver and gold nanoparticles

Surface-enhanced Raman scattering (SERS) spectra of the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) and its monomer 3,4-ethylenedioxythiophene (EDOT) on Ag and Au nanoparticles presenting different morphologies and stabilizing agents have been obtained using the excitation radiation at 633 nm. The SERS spectra of the monomer and polymer are strongly dependent both on the metal and capping agent of the substrate. SERS spectra of EDOT on Au nanospheres indicates that adsorption occurs with the thiophene ring perpendicular to the metal surface. In contrast, polymerization takes place on the silver surface of Ag nanospheres. EDOT adsorption on Ag nanoprisms with polyvinylpyrrolidone (PVP) as capping agent occurs similarly to that observed on gold. Surface-enhanced resonance Raman scattering (SERRS) spectra of PEDOT on gold nanostars that present a thick layer of PVP show no chemical interaction of PEDOT with the metal surface; however, when PEDOT is adsorbed on citrate stabilized gold nanospheres, the SERRS spectra suggest that thiophene rings are perpendicular to the surface. Oxidation of PEDOT also is observed on Ag nanospheres. The investigation of the interface between PEDOT and metal surface is crucial for the development in polymer-based optoelectronic devices since this interface plays a crucial role in their stability and performance.     

Preparation and photochromic properties of nanocomposites based on chemically cross-linked polyvinyl alcohol and phosphotungstic acid

Nanocomposite films based on cross-linked polyvinyl alcohol (PVA) and phosphotungstic acid (PTA), in which PTA plays the roles of photochromic component and catalyst of the chemical cross-linking of PVA with glutaric aldehyde (GA), were synthesized. The formation of chemical cross-links in a polymer matrix of nanocomposite films occurring during their formation from PVA-PTA-GA aqueous solutions, was confirmed by IR spectroscopy. It was found that the cross-linkage of a polymer matrix imparts water resistance to PVA/PTA nanocomposites and changes their photochromic properties. By analyzing the electronic absorption spectra of photocolored films, it was shown that PTA anions in the matrix of non-cross-linked PVA upon photoreduction receive only one electron, while not only one-electron but the two-electron reduction of PVA anions occurs in a cross-linked PVA matrix. The photocolorabilty of films based on cross-linked PVA is thus two times higher than that of films based on non-cross-linked PVA. It was found that the rate of discoloration of photocolored PVA/PTA films increases with an increase in the degree of cross-linking of a polymer matrix.     

Nanostructured ultra-low-κ porous fluoropolymer composite films via plasma co-polymerization of hydrophobic and hydrophilic monomers and subsequent hydrolysis treatment

A new approach to fabricate porous nanostructured fluoropolymer composite films with a low dielectric constant (κ) was put forward at the first time. Initially, a film (pp-HDFD-PEGMA film) composed of dense, uniform, and well-defined nanospheres was controllably deposited on hydrogen-terminated silicon substrates by simultaneous plasma polymerization and deposition of a fluorine-containing hydrophobic monomer, 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluoro-1-decene (HDFD), and a hydrophilic monomer poly(ethylene glycol) methacrylate (PEGMA), using a pulsed plasma polymerization technique. Then, by hydrolysing the plasma co-deposited film in aqueous hydrochloric acid solution to effectively remove the soluble nanospheres or fragments which mainly derived from PEGMA, a nanoporous fluorocarbon film was achieved. Subsequently, a top poly(tetrafluoroethylene) layer was deposited via the magnetron sputtering process to cap and complete an encapsulated structure. The resulting bilayer composite film consisting of a layer of nanostructured fluorocarbon porous film and a layer of encapsulation fluorocarbon polymer has a κ value of 1.8. The morphology investigation of the plasma co-deposited film prior and after acid-treatment by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) confirmed the form of the nanospheres and nanoporous structure, while the chemical composition and structure analysis by X-ray photoelectron spectroscopy (XPS) revealed that after the acid-treatment, the porous nanostructured film are composed predominantly of mainly fluorocarbon polymer.     

Anionic polymer hydrogel degradation by ascorbic acid

Polymer hydrogel based on sodium 2-acrylamido-2-methylpropansulfonate, covalently crosslinked with N,N′-methylenebisacrylamide has been shown to degrade in aqueous ascorbic acid. The hydrogel degradation is induced by chemical interaction of the polymer crosslink and an ascorbic acid oxidation intermediate.     

Silicon-titanium xerogels: Synthesis and application to the determination of ascorbic acid and polyphenoles

Titanium and silicon-titanium xerogels have been obtained and it has been demonstrated that titanium(IV) incorporated into the xerogel matrix can participate in complexation reactions with ascorbic, gallic, ferulic, and caffeic acids and also rutin, quercetin, and dihydroquercetin present in aqueous solutions. In the case of dihydroquercetin 1 min of contact has been sufficient for achieving the equilibrium; the other compounds required 7–10 min. The stability constants of titanium(IV) complexes incorporated into xerogels reduced in the order dihydroquercetin > gallic acid > ascorbic acid > quercetin > caffeic acid > rutin. The procedures have been developed for solid-phase spectrophotometric determination of ascorbic, gallic, ferulic, caffeic acid as well as rutin, quercetin, and dihydroquercetin. The accuracy of the procedure has been examined by the standard addition method. The procedures for the determination of dihydroquercetin and ascorbic acid have been applied to the analysis of pharmaceutical preparations.     

Peptide‐poly(tert‐butyl methacrylate) conjugate into composite micelles in organic solvents versus peptide‐poly(methacrylic acid) conjugate into spherical and worm‐like micelles in water: Synthesis and self‐assembly

Peptide–polymer conjugates are versatile class of biomaterials composed of a peptide block covalently linked with a synthetic polymer block. This report demonstrates the synthesis of peptide‐poly(tert‐butyl methacrylate) (Peptide‐P^tBMA) conjugates of varying molecular weights via a “grafting from” atom transfer radical polymerization (ATRP) technique using as‐synthesized peptide‐based initiator in toluene. Peptide‐P^tBMA conjugate is soluble in many organic solvents and undergoes self‐assembly into micro/nanospheres in DMF/THF as observed from both FESEM and DLS results. The conjugate micro/nanospheres are nothing but the composite micelles formed by the secondary aggregation of primary micelles generated initially in these organic solvents. The hydrolysis of tert‐butyl groups of Peptide‐P^tBMA conjugate leads to the formation of peptide‐poly(methacrylic acid) (Peptide‐PMA) conjugate. The circular dichroism (CD) analysis exhibits the presence of β‐sheet conformation of peptide moiety in synthesized conjugates. The formed Peptide‐PMA conjugate is soluble in water and owing to its amphiphilic character, the conjugate molecules self‐assemble into spherical micelles as well as worm‐like micelles upon increasing the concentration of conjugate in water. However, the sodium salt of Peptide‐PMA conjugates (Peptide‐PMAS) self‐assembles into only spherical swollen micelles in water at higher (pH ～10). The critical aggregation concentrations (CACs) of both Peptide‐PMA and Peptide‐PMAS micelles are measured by fluorescence spectroscopy. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3019–3031