Design of robust and photoluminescence‐responsive materials based on poly(methacrylic acid‐co‐m‐phenylenediamine) with graphene oxide composite hydrogels and its adsorption

A promising strategy to design crosslinked photoluminescent hydrogel (PL hydrogel) is to synthesize the covalently bonded polymer chains by thermal polymerization. A proper ratio of methacrylic acid and m‐phenylenediamine was used to prepare the PL hydrogel, and doping with graphene oxide and carboxymethyl chitosan improves the structure of the gel. The green and efficient hydrothermal synthesis realized a high polymerization and a short reaction time. Meanwhile, a series of properties were investigated for several combinations of hydrogels. Ultraviolet spectra, fluorescence spectra, and particle size distributions were used to characterize the PL composites. Scanning electron microscopy, Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, thermogravimetric analysis, rheological studies, and stress–strain tests were conducted to characterize the morphology, structure, and performance of the compound hydrogel. The adsorption properties of the PL hydrogel were characterized in adsorption tests. The results indicated that the PL hydrogel exhibited a favorable luminescence property, a certain degree of mechanical strength, and good adsorption performance. The prepared PL hydrogel has potential applications in adsorption and visual detection. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46354.     

Removal of heavy metal ions from aqueous solutions by radiation‐induced chitosan/(acrylamidoglycolic acid‐co‐acrylic acid) magnetic nanopolymer

An effective method was developed to isolate toxic heavy metal ions from the aqueous solution by the magnetic nanopolymers. The magnetic sorbent was prepared with radiation‐induced crosslinking polymerization of chitosan (CS), 2‐acrylamido‐glycolic acid (AMGA), and acrylic acid (AAc), which stabilized by magnetite (Fe₃O₄) as nanoparticles. The formation of magnetic nanoparticles (MNPs) into the hydrogel networks was confirmed by Fourier transform infrared spectroscopy, X‐ray diffraction, transmission electron microscopy, and Scanning electron microscopy, which revealed the formation of MNPs throughout the hydrogel networks. The swelling behavior of the hydrogels and magnetic ones was evaluated at different pH values. The adsorption activity for heavy metals such as Cu²⁺ and Co²⁺ by nonmagnetic and magnetic hydrogels, Fe₃O₄/CS/(AMGA‐co‐AAc), in terms of adsorption amount was studied. It was revealed that hydrogel networks with magnetic properties can effectively be used in the removal of heavy metal ions pollutants and provide advantageous over conventional ones. POLYM. ENG. SCI., 55:1441–1449, 2015. © 2015 Society of Plastics Engineers     

Synthesis,characterization and swelling behavior of chitosan‐sucrose as a novel full‐polysaccharide superabsorbent hydrogel

A novel full‐polysaccharide hydrogel was prepared by crosslinking of chitosan with periodate‐oxidized sucrose. A tetraaldehyde molecule is synthesized via periodate oxidation of sucrose and then applied as a crosslinking agent to form a new hydrogel network. A mechanism for the superabsorbent hydrogel formation via reductive N‐alkylation was also suggested. The structure of the hydrogel was confirmed by FTIR spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). It is shown that crosslinking of chitosan can improve its thermal stability. The effects of crosslinker concentration, pH, and inorganic salt on the swelling behavior of the hydrogel were studied. The results indicate that the hydrogel has good pH sensitivity and pH reversible response. The smart hydrogels may have potential applications in the controlled delivery of bioactive agents and for wound‐dressing application © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Control of swelling properties of polyvinyl alcohol/hyaluronic acid hydrogels for the encapsulation of chondrocyte cells

Hydrogel scaffolds for tissue engineering are important biomaterials. The target in this study was to prepare polyvinyl alcohol/hyaluronic acid hydrogels for the encapsulation of chondrocyte cells by a simple cross‐linking reaction. Control of the swelling properties and morphology of the hydrogels for cultivation of chondrocytes was studied. The hydrogels were prepared from polyvinyl alcohol and hyaluronic acid derivatives bearing primary amine and aldehyde functionalities, respectively. The formation of the hydrogel upon mixing the aqueous solutions of the polymer derivatives took place at room temperature in a few seconds. The swelling properties of the hydrogels were found to depend on the polymer concentration and degree of substitution of the modified polymers. Scanning electron microscopy studies showed that the hydrogels had a suitable porous morphology for cell encapsulation. Furthermore, in vitro cell viability tests with the hydrogels showed no cytotoxicity for chondrocytes and that the cells grew well in the hydrogel scaffolds. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42272.     

Development of microbial protective Kolliphor‐based nanocomposite hydrogels

In this scientific work, a novel class of antimicrobial nanocomposite hydrogels were designed and synthesized by chemical and environmentally bioprocess using Kolliphor, acrylamide, and mint leafs in order to achieve antiseptic property for wound applications. In the bioprocess approach, silver nitrate and gold chloride were nucleated with mint leafs in order to obtain effective free individual nano‐inorganic compounds to provide superior antibacterial assets. The formations of dual inorganic nanoparticles were confirmed by transmission electron microscopy, which indicated the size of nanoparticles in the range of approximately 3 ± 2 nm and without agglomeration. The formations of biomaterials were characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopic–energy dispersive spectrometric studies and their swelling properties were determined. Furthermore, the pure hydrogel and the dual inorganic nanocomposite hydrogels developed were tested for antibacterial activities. When compared with the neat hydrogel, the nanocomposite hydrogels significantly improved their anti‐bacterial activities on Bacillus bacterium. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42781.     

Synthesis of a cellulose‐based hydrogel network: Characterization and study of urea fertilizer slow release

In the present study, we synthesized a low‐cost biodegradable hydrogel based on cellulose in order to perform controlled release of fertilizer. For this purpose, the cellulose was modified and crosslinked with urea. Then the prepared hydrogel underwent loading with the fertilizer in order to study the controlled release. Characterization of the samples was carried out by Fourier Transform Infrared (FT‐IR) spectroscopy, elemental analysis, thermal gravimetric analysis (TGA), and scanning electron microscopy (SEM). The hydrogel showed a good swelling behavior in distilled water, tap water, and 0.9% NaCl solution. Besides, water holding and water retention behavior of the hydrogel was investigated. Finally, the release of fertilizer from the loaded hydrogel was studied and showed excellent controlled release. According to the results, this hydrogel can be employed as a suitable moisture‐holding additive in the soil for agricultural purposes. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42935.     

Hydrolyzed polyacrylonitrile‐blend‐soy protein hydrogel fibers: a study of structure and dynamic pH response

BACKGROUND: The introduction of protein into polyacrylonitrile artificial muscle systems has been shown to be a good way to achieve quicker and better responses. This research work mainly focused on the structure and dynamic pH response of hybrid hydrolyzed polyacrylonitirile‐blend‐soy protein (H‐PAN/SP) hydrogel fibers. RESULTS: The micro‐morphology and swelling/shrinking kinetics of H‐PAN/SP hydrogel fibers were investigated using scanning electron microscopy and elongation/contraction experiments with different fiber diameters, concentration of crosslinker and temperature. The results revealed good consistency between Tanaka–Fillmore theory and the surface morphology of the multi‐porous microstructures of the fibers. In addition, the crosslinking density and temperature had a great impact on the pH response of the hydrogel fibers, consistent with Flory–Huggins theory. Hydrogel fibers with a high content of soy protein showed an excellent and stable pH response. CONCLUSION: Studies of dynamic elongation and contraction behavior assist in the understanding and control of the pH response of H‐PAN/SP hydrogel fibers. Copyright © 2008 Society of Chemical Industry     

Facile preparation and characterization of sodium alginate/graphite conductive composite hydrogel

Conductive composite hydrogels based on sodium alginate (SA) and graphite were fabricated by a facile method via dispersing homogeneously conductive graphite into SA hydrogel matrix. The hydrogel was formed by in situ release of Ca²⁺ from Ca–EDTA, thus eliminating the multistep reactions and tedious purification compared to the previous work. Raman spectra, scanning electron microscopy (SEM), X‐ray diffraction (XRD), and thermogravimetric analysis (TGA) were used to characterize the structure, crystalline nature, and thermostability of SA/graphite composite hydrogels. The SA/graphite composite hydrogels exhibited the improved network and layer‐type structure. The thermal stability of the hydrogel decreased slightly after the graphite was incorporated into the SA hydrogel matrix regardless of the content of graphite. The enhanced mechanical strength of SA/graphite composite hydrogel was achieved via increasing the f value (i.e., [Ca²⁺]/[COO^‐ in alginate]) and lowering graphite content. The conductivity of the composite hydrogels could be varied in a broad range, reaching up to 10⁻³ S/cm, mainly depending on the content of graphite and the f value. POLYM. COMPOS., 37:3050–3056, 2016. © 2015 Society of Plastics Engineers     

Preparation and characterization of composite hydrogels based on crosslinked hyaluronic acid and sodium alginate

In this study, a novel composite hydrogel with improved cellular structure and mechanical properties was prepared by the crosslinking of hyaluronic acid (HA) and sodium alginate (SAL). The amide linkages (covalent bonds) in the hydrogel that we expected to form were confirmed by Fourier transform infrared spectroscopy. The hydrogels had a pore size larger than 100 μm and were observed by scanning electron microscopy. Texture profile analysis indicated that the hardness of the hydrogels was enhanced by an increase in the polymer's concentration, but it declined with an increase in the HA/SAL molar ratio. The swelling capacity was reduced with increases in the polymer's concentration and the 1‐ethyl‐3‐(3‐dimethyl aminopropyl)‐1‐carbodiimide hydrochloride (EDC)/HA molar ratio, and it was enhanced by an increase in the HA/SAL molar ratio. The resistance against hyaluronidase was negatively correlated with the proportion of HA in the hydrogels and positively correlated with the EDC/HA molar ratio. Given the improved physicochemical properties that we produced, these novel hydrogels may have the potential to be applied in tissue engineering scaffolding. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41898.     

The effects of graphene oxide on the properties and drug delivery of konjac glucomannan hydrogel

Konjac glucomannan (KGM) hydrogel has good potential application in food and medical science, although to achieve this, the physical and mechanical properties need further improvement. In this study, graphene oxide (GO) was used to improve the functionality of KGM hydrogel. KGM/GO hydrogels were prepared by freezing the alkaline KGM/GO sols. Rotational rheometer was used to study the rheological properties of different alkaline KGM/GO sols. Fourier transform infrared, Raman, differential scanning calorimetry, thermogravimetric analyses, and scanning electron microscopy were used to evaluate the structure and properties of the hydrogels. In addition, different pH solutions and an in vitro assay were used to study the swelling property and the release behavior of KGM/GO hydrogels, respectively. The result revealed strong hydrogen‐bond interaction between KGM and GO. The incorporation of GO highly improved the gel properties of KGM/GO sol, higher thermal stability, and more compact structure of KGM/GO hydrogels. KGM/GO hydrogels showed better swelling properties in deionized‐distilled water and pH 7.2 PBS. The release of 5‐aminosalicylic acid (5‐ASA) from KGM/GO (KG4) hydrogel was different in various pH media, but the initial burst release effect was very severe. Therefore, incorporation of GO have a good potential in enhancing the properties of KGM hydrogel, but KGM/GO hydrogel is not an ideal carrier for 5‐ASA release. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45327.     

Facile synthesis and antibacterial evaluation of poly(acrylamide‐co‐(β‐cyclodextrin))/silver nanocomposite

Hydrogel/silver nanocomposites have shown immense potential in many biological applications. In this article, a facile method to synthesize poly(acrylamide‐co‐(β‐cyclodextrin))/silver nanocomposites is reported. The silver nanoparticles were in situ synthesized accompanying with the formation of poly(acrylamide‐co‐(β‐cyclodextrin)) hydrogel by gamma irradiation without additional reducing and stabilizing agents. In addition, the nanocomposites were prepared under ambient conditions. The formation of silver nanoparticles was confirmed by ultraviolet used to characterize the structure and composition of the synthetic nanocomposites. Transmission electron microscope verified the formation and homogeneous distribution of silver nanoparticles in the hydrogel matrix. The hybrid hydrogel exhibited excellent water‐swelling properties, which could be controlled by varying the mass ratio of acrylamide (AM) to β‐cyclodextrin (β‐CD) in the hydrogel. Furthermore, the poly(acrylamide‐co‐(β‐cyclodextrin))/silver nanocomposites were found to be effective in inhibiting the growth of both Gram‐negative Escherichia coli and Gram‐positive Staphylococcus aureus. POLYM. COMPOS., 37:1480–1487, 2016. © 2014 Society of Plastics Engineers     

Preparations,properties, and formation mechanism of novel cellulose hydrogel membrane based on ionic liquid

Cellulose hydrogel membranes were successfully produced by casting the cellulose/1‐butyl‐3‐methylimidazolium chloride (BmimCl) solution into assembling molds, and then coagulated in water. The morphological features and mechanical properties of the prepared hydrogel membranes were characterized by a series of techniques including X‐ray diffraction measurements, scanning electron microscopy measurements, UV–visible light absorption spectrum, and tensile testing. The formation mechanism and the effects of different pre‐gelation temperature, pre‐gelation time, and coagulation batch temperature on the morphology and property of prepared cellulose hydrogel membranes were explored. The result shows that the hydrogel membrane of cellulose with excellent performance can be prepared adopting novel ionic liquid (BmimCl) as solvent through suitable process; the prepared hydrogel membranes present good mechanical properties and excellent transparency. In addition, the model of the hydrogel formation is established. It is believed that this is a promising material in the application of biomedical engineering and medical material. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45488.     

Macromolecular assemblies of segmented poly(ester urethane)s and poly(ether urethane)s

Polyurethanes containing different soft and hard segments were investigated by fluorescence and scanning electron microscopy. The polarity dependence of the vibrational structure of the pyrene emission spectrum indicated the formation of aggregates at concentrations, which are significantly below the critical concentrations, which define the separation of dilute‐semidilute domains. Unlike the samples with 4,4′‐methylene diphenylene diisocyanate, the samples with 2,4‐tolylene diisocyanate in hard segments give the fluorescence spectra in which the pyrene excimer appears. The supermolecular structures associated with the form of spherulites or of spherical micelles were detected by scanning electron microscopy. The results were compared with previous reports concerning viscometric data. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation and characterization of pH responsive poly(methacrylic acid‐acrylamide‐N‐hydroxyethyl acrylamide) hydrogels for drug delivery systems

In this study, pH responsive polymers composed of methacrylic acid, acrylamide, and N‐hydroxyethyl acrylamide were synthesized by free radical polymerization technique. The characterization was done with Fourier transform infrared spectroscopy and scanning electron microscopy. The swelling and drug release behavior of the hydrogels was determined as a function of time at 37°C in pH 2.1 and 7.4. The swelling and drug release studies showed that increased methacrylic acid amount caused a higher increase in swelling and drug release values at pH 7.4 than those at pH 2.1. In addition, the drug release data were applied to kinetic models such as zero order, first order, and Higuchi equations, and it fit well in the Higuchi model of the hydrogel. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43226.     

Preparation of a hydroxyethyl–titanium dioxide–carboxymethyl cellulose hydrogel cage and its effect on the removal of methylene blue

A novel TiO₂ hydrogel cage model was built for the removal of methylene blue (MB), an organic pollutant. This TiO₂ hydrogel cage was prepared with the biomass materials of hydroxyethyl cellulose (HEC) and carboxymethyl cellulose (CMC), and this hydrogel cage structure was characterized by scanning electron microscopy, transmission electron microscopy, and X‐ray diffraction. The contents of the encased TiO₂ and its swelling properties with different CMC proportions of this hydrogel cage were studied to obtain a suitable crosslinking network structure and optimal synthesis conditions. Compared to an equivalent amount of pure TiO₂, the much higher removal efficiency of MB with our prepared TiO₂ hydrogel cage was attributed to the synergistic effect of the photocatalytic degradation for TiO₂ and the adsorption enrichment for cellulose hydrogels. Furthermore, the adsorption kinetics of the intraparticle diffusion model were used to study the adsorption enrichment process of the TiO₂ hydrogel cage. In addition, on the basis of the results of photocatalytic degradation and recycling experiments, excellent performances with respect to self‐cleaning, regenerative ability, and easy recovery, were shown for this HEC–TiO₂–CMC cage material, which demonstrated ideal application potential for MB removal. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44925.     

Development of a superporous hydroxyethyl cellulose‐based hydrogel by anionic surfactant micelle templating with fast swelling and superabsorbent properties

The self‐assembling anionic surfactant, sodium n‐dodecyl sulfonate (SDS) micelles were used as pore‐forming templating for fabricating novel superporous hydroxyethyl cellulose‐grafting‐poly(sodium acrylate)/attapulgite (HEC‐g‐PNaA/APT) hydrogels. The network characteristics, morphologies of the hydrogels and removing of SDS micelles from the final product by washing with ethanol/water (v/v, 7 : 3) procedure were determined by Fourier transform infrared spectroscopy and scanning electron microscopy, as well as by determination of swelling ratio, swelling rate, and stimuli response to salts and pHs. The results showed that the added‐SDS concentration significantly affected the morphologies and pore structure of the hydrogel, and 2 mM SDS facilitates to form a homogeneous and well‐defined pore structure in the gel network to extremely improve the swelling ratio and swelling rate. The 2 mM SDS‐added superporous HEC‐based hydrogel not only had highest equilibrium swelling ratio (Q_eq, 1118, 102 g g^?1 in distilled water and 0.9 wt % NaCl solution), rapid swelling rate (k_is, 5.2840 g g s^?1), also showed multistimulus responses to salts and pHs, which may allow its applications in several areas such as adsorption, separation and biomedical materials. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42027.     

Protein‐imprinted polyurethane‐grafted calcium alginate hydrogel microspheres

Protein‐imprinted polyurethane‐grafted calcium alginate hydrogel microspheres were prepared and characterized. The samples were investigated with optical microscopy, scanning electron microscopy, ¹³C‐NMR, and Fourier transform infrared spectroscopy. We proved that polyurethane side chains were successfully grafted, and this led to a relatively rough and dense surface. The samples exhibited better swelling durability when applied in specific adsorption tests. The adsorption kinetic and recognition properties indicated that the imprinted modified microspheres had excellent rebinding affinity toward the target proteins. Moreover, the influence of the preassembly pH, rebinding pH, and grafting ratio on the adsorption capacity and imprinting efficiency (IE) were systematically investigated. The study results suggest that the modified samples possessed a higher IE toward the target protein under the optimum pH and grafting ratio. Upon polyurethane grafting modification, the alginate hydrogel microspheres showed improved mechanical stability and recognition specificity. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42140.     

Zinc ion‐induced formation of hierarchical N‐succinyl chitosan film

A series of N‐succinyl Chitosan (NSCS) hydrogel derived from different substitution degree of NSCS were fabricated through the zinc ions crosslinking. Subsequently, a light‐weight, transparent, and hierarchical NSCS‐Zn(II) film was obtained by drying the hydrogel. The hierarchical structure of NSCS‐Zn(II) film was confirmed by scanning electron microscopy. The NSCS‐Zn(II) film exhibited excellent mechanical strength because of the preferential formation of the alignment structure. The tensile strength and Young's modulus reaches 119.3 MPa and 2.67 GPa when the NSCS substitution degree was 91.95%. Furthermore, a remarkable and enhanced broad‐spectrum bactericidal properties of the NSCS‐Zn(II) film was revealed through E. coli and S. aureus exposure, respectively. These features indicated that NSCS‐Zn(II) film is a promising material that can be used in biomedical engineering. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44664.     

Preparation of glucose‐sensitive and fluorescence micelles via a combination of photoinitiated polymerization and chemoenzymatic transesterification for the controlled release of insulin

Glucose‐sensitive and fluorescence copolymer micelles were designed and prepared via a combination of photoinitiated polymerization and enzymatic transesterification. The water‐soluble photoinitiator and emulsifier 2‐oxooctanoic acid self‐polymerized dimer molecules under UV irradiation were characterized by mass spectrometry. The fluorescence dye (9‐anthracene alcohol) and biocompatible hydrophilic chains [poly(ethylene glycol)] were introduced to the polymer chains during the photopolymerization and enzymatic transesterification processes. The as‐prepared copolymers were confirmed by ¹H‐NMR spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, and dynamic light scattering. The resulting copolymers exhibited excellent glucose sensitivity and stability against protein. The optical fluorescence properties of the copolymer micelles were investigated with fluorescence spectrophotometry, fluorescence microscopy, and confocal laser scanning microscopy. Because of the amphiphilic feature, the micelles could be self‐assembled and used to load insulin. The controlled release of insulin was evaluated and was triggered by glucose in vitro. This study provided a new strategy for fabricating functional carriers as self‐regulated insulin‐release systems. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43026.     

Preparation and swelling properties of homopolymeric alginic acid fractions/poly(N‐isopropyl acrylamide) graft copolymers

Graft copolymers of crosslinked poly(N‐isopropyl acrylamide) (PNIPAAm) and homopolyguluronic acid (GG) and homopolymannuronic acid (MM) fractions of alginic acid were synthesized. MM and GG block fractions were obtained by partial acid hydrolysis of the alkaline extract from the brown seaweed Macrocystis pyrifera. The conjugation of these block fractions with the synthetic polymer was achieved by amidation with crosslinked PNIPAAm functionalized with an amino group at the end of the polymer chain. The structure of conjugates was determined by Fourier transform infrared and NMR spectroscopy. Atomic force microscopy of the graft copolymer GG‐g‐PNIPAAm showed a regular porous pattern, whereas the MM‐g‐PNIPAAm graft copolymer showed a regular netlike structure. Aqueous solutions of the synthesized graft copolymers afforded hydrogels by stirring with 0.1M CaCl₂. The hydrogels showed a well‐defined stimulus–response to temperature and pH. The swelling, thermal, and pH characterizations demonstrated the superior properties of the GG‐g‐PNIPAAm hydrogel over the MM‐g‐PNIPAAm hydrogel. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42398.