Addition Of Cross-linking Agent Research Articles

Features of printing textile materials with pigments and the use of water dispersions of synthetic copolymers

In pigment printing, a pressing issue is the search for new binders for printing inks. The work examines the search for accessible and cheap polymer preparations that have cross-linking properties and are capable of forming strong, elastic and transparent films to create an effective low-component and environmentally friendly pigment printing technology. The use of polyurethane dispersions in various proportions with additional cross-linking agents has been studied. They used methazine, carbamol GL, and PVA. For the Aquapol - Methazine mixture, it is necessary to use the ratio with the lowest content of thermosetting resin precondensates. When using PVA, the optimal ratio is 1:1. When adding Aquapol 12, the color fastness to dry rubbing and washing is 5 points. PVA increases the adhesion of the print to the fabric. In the case of PVA, the fingerboard is softer. With increasing concentration of PVA in the composition, the hardness either does not change or decreases. After modification of polyurethane dispersions with PVA, its use is economically beneficial.

Injectable-Hydrogel-Based Tissue Sealant for Hemostasis, Bacteria Inhibition, and Pro-Angiogenesis in Organ Bleeding Wounds and Therapeutic Outcome Monitoring Via NIR-II Optical Imaging.

Sudden hemorrhage stemming from internal organ wounds poses a grave and potentially fatal risk if left untreated. Injectable-hydrogel-based tissue sealants featuring multiple actions, including fit-to-shape in situ gelation, rapid hemostasis, pro-angiogenic, anti-bacterial and outcome tracking, are ideal for the management of organ trauma wounds. Herein, an injectable-hydrogel tissue sealant AN@CD-PEG&TQ which consists of four-arm 4-arm poly(ethylene glycol) (PEG-SC) succinimidyl carbonate), AN@CD nanoprobe, and two bioactive peptides (anti-microbial peptide Tet213 and pro-angiogenic peptide QK) is developed. Among them, AN@CD nanoparticles form through host/guest complexation of amino-group-containing β-cyclodextrin and adamantyl group, enabling in situ biomarker (NO)-activatable optoacoustic/NIR-II: Near-infrared second biological window fluorescent imaging. The ample ─NH2 groups on the surface of AN@CD readily engage in rapid cross-linking with succinimidyl ester groups located at the ends of four-arm PEG-SC. This cross-linking expedites the gelation process without necessitating additional initiators or cross-linking agents; thus, significantly enhancing both hydrogel's application convenience and biocompatibility. Bioactive peptides (Tet213 and QK) safeguard against possible bacterial infections, facilitate angiogenesis, and eventually, improve organ wounds healing. This hydrogel-based tissue sealant demonstrates superior therapeutic and bioimaging performance in various mouse models including liver hemorrhage, gastric perforation, and bacterial-infected skin wound mouse models, highlighting its potential as a high-performance wound sealant for organ bleeding wound management.

An efficient fabrication method of lightweight aramid nanofibrous aerogels for high-efficient sound absorption and thermal properties

The aramid nanofibrous aerogels (ANFs) have various application prospects due to their ultra-light, high porosity and excellent properties of aramid fibers. However, the preparation of ANFs requires long preparation time and their ultra-dense pore structure leads to poor sound penetration and high sound energy reflectivity, which ultimately makes the overall sound absorption performance of ANFs poor. Therefore, a strategy for synthesis of ANFs is designed to achieve light weight, excellent thermal insulation performance and significantly improve sound absorption properties. This strategy combines cell pulverizing, pump-filtration molding, and directional freezing to ensure structural strength of the aerogel without the addition of cross-linking agents, and this process enables the ANFs to introduce in macro-pores while keeping nano-pores. The structure of multi-layered pores effectively reduces the reflectivity of incident acoustic energy and improves the sound absorption coefficient. The interconnected macro-pores and interlaced small pores of ANFs provide good sound absorption performance (sound absorption average (SAA) = 0.338), excellent flame retardant and thermal insulation properties (thermal conductivity = 0.0635 W (m*K)−1) with ultralight (density = 40.5 mg cm−3) in a thinner thickness (15 mm), which extend the potential of ANFs in areas of noise control and thermal insulation. In addition, the structure of multi-scaled pores can also be formed inside other aerogels by using the method of cell pulverization and filtration preparation, which can be helpful for improving their properties of thermal insulation and sound absorption.

Nano-injectable pH/NIR-responsive hydrogel for chemo-photothermal synergistic drug delivery.

Conventional cancer treatments are highly toxic and ineffective; therefore, it is essential to develop less toxic and minimally invasive treatment methods. A pH/Near Infra-red (NIR) dual-responsive, nano-injectable smart hydrogel was fabricated by incorporating CuS nanoparticles into the hydrogel networks formed by a random copolymer of N-isopropylacrylamide (NIPAM) and double-bond functionalized uracil. Microstructural characterizations of synthesized polymer and hydrogels were carried out using transmission electron microscope (TEM), scanning electron microscope (SEM), nuclear magnetic resonance (NMR) and fourier transform infrared spectroscopy (FT-IR). Multiple hydrogen bonding interactions between uracils function as physical cross-linking points to construct the network structure of the polymeric nanogel without the addition of additional cross-linking agents, ensuring the material's safety. The amino group on the structure of uracil gives the uracil-modified polymeric hydrogel excellent pH responsiveness. Notably, as a temperature-responsive material, poly (N-isopropylacrylamide) (PNIPAM) nanogel solution can achieve in situ gel formation (within 100 s at 37°C) above its lower critical solution temperature (LCST), granting injectability to polymeric solutions. Moreover, using a hierarchical construction strategy, the variable loading of DOX and CuS was achieved. First, a heterogeneous system was created by encapsulating doxorubicin (DOX) inside the nanogel via hydrophobic and π-π stacking interactions, followed by the introduction of CuS nanoparticles as photosensitizers outside of the nanogels. Due to the presence of CuS nanoparticles, the gel is able to convert NIR light into local heat to enhance the destruction of tumor cells while simultaneously achieving rapid in situ gel formation. The in situ-forming hydrogel showed promising tissue biocompatibility. The in vitro antitumor test demonstrated the capacity of the nanocomposite hydrogel for chemo-photothermal synergistic therapy. Therefore, this prepared platform has the potential to become a safe and effective, smart-responsive drug carrier for chemotherapy and PTT synergy, a minimally invasive material for tumor treatment.

Tailored hydrogel entrapped catalyst with highly active, controlled catalytic activity for the removal of 4-nitrophenol (4-NP)

In catalytic reactions, achieving large specific surface area immobilisation of the catalyst is an important factor affecting the catalytic effect, however, the primary challenges in utilizing hydrogels as catalyst carriers are to enhance the mechanical properties of the hydrogel to improve the activity and controllability of the catalyst. In this study, a new structure of P(AM-co-AA)/SMA/NH2-SiO2 hydrogels was synthesized via free radical polymerization, and the effects of the content of AA and NH2-SiO2 on the mechanical properties of the hydrogels were investigated. Without the use of additional cross-linking agents, both a chemical cross-linking network and a hydrophobic linkage network were established, which effectively reconstructed the structure of the hydrogels and dissipated energy. As a result, P(AM-co-AA-1.5 %)/SMA/NH2-SiO2-0.5 % hydrogel exhibited high mechanical properties, with tensile strength, elongation, and toughness reaching 1456 KPa, 4605 %, and 23.59 MJ/m3, respectively. This hydrogel can be utilized as a template for in situ and stable Ag NPs. Additionally, P(AM-co-AA)/SMA/NH2-SiO2@Ag composite hydrogels were prepared using cation exchange and in situ reduction methods for the catalytic reduction of 4-nitrophenol (4-NP). The composite hydrogel exhibited fast catalysis, high efficiency, stable cycling, recyclability and adjustable catalytic activity at 35 °C with Kapp = 0.811 min−1. Furthermore, using this composite hydrogel alleviated the need for separating metal nanoparticle catalysts from the reaction system, thereby enabling the development of robust hydrogel materials with controlled catalytic activity for the wastewater treatment industry.

Fabrication of water-in-oil-in-gel emulsion gel based on pH-shifting soybean lipophilic protein and carboxymethyl chitosan: Gel performance, physicochemical properties and digestive characteristics

In this study, Soybean lipophilic protein (LP) was modified by pH-shifting treatment and the modified LP was cross-linked with carboxymethyl chitosan (CMCS) to form an interpenetrating network structure to prepare water-in-oli-in-gel emulsion gels (W/O/G). The effects of the variation of phase ratio and addition of cross-linking agent (genipin) on the physicochemical properties and digestive characteristics of W/O/G were investigated. FT-IR and intermolecular force analysis showed that pH-shifting treatment exposed more hydrophobic groups in LP, and promoted the increase of intermolecular hydrophobic interaction and hydrogen bonding force. With the increase of GP addition and W1/O ratio, the swelling rate, water-holding capacity and UV stability of W/O/G gradually increased. While the porosity, encapsulation efficiency and in vitro degradation rate kept decreasing. W/O/G exhibited thixotropy in rheological tests and withstood a maximum compressive force of 1870 mN at a strain of 40%. Additionally, CMCS confered a certain pH response capability to W/O/G, which both maintained the gel network during pH changes and enabled the slow-release of the encapsulated bioactive in simulated in vitro digestion and improves bioaccessibility up to 80.63%. This study provided a theoretical basis for the cross-linking of modified LP and CMCS to form interpenetrating networks and enriched the gelation treatment of W/O/W emulsions.

Degradable carrier-free spray hydrogel based on self-assembly of natural small molecule for prevention of postoperative adhesion.

Postoperative peritoneal adhesion (PPA) is frequent and extremely dangerous complication after surgery. Different tactics have been developed to reduce it. However, creating a postoperative adhesion method that is multifunctional, biodegradable, biocompatible, low-toxic but highly effective, and therapeutically applicable is still a challenge. Herein, we have prepared a degradable spray glycyrrhetinic acid hydrogel (GAG) based on natural glycyrrhetinic acid (GA) by straightforward heating and cooling without the use of any additional chemical cross-linking agents to prevent postoperative adhesion. The resultant hydrogel was demonstrated to possess various superior anti-inflammatory activity, and multiple functions, such as excellent degradability and biocompatibility. Specifically, spraying characteristic and excellent antibacterial activities essentially eliminated secondary infections during the administration of drugs in surgical wounds. In the rat models, the carrier-free spray GAG could not only slow-release GA to inhibit inflammatory response, but also serve as physical anti-adhesion barrier to reduce collagen deposition and fibrosis. The sprayed GAG would shed a new light on the prevention of postoperative adhesion and broaden the application of the hydrogels based on natural products in biomedical fields.

Self-crosslinked alkaline polyelectrolyte membranes with exceptional stability under dry-wet alternating conditions

The emergence of alkaline polyelectrolytes (APEs) with high stability and high ionic conductivity has greatly improved the power density of alkaline polyelectrolyte fuel cells (APEFCs), now the cell stability has become an urgent problem to be addressed. The uneven distribution of humidity and hydration state inside large-scale electrodes will cause the membrane to swell and shrink repeatedly, resulting in the membrane rupture and/or the peeling off of catalyst layers, which is a fatal problem affecting the stability of APEFCs. In the present work, we report a new APE, self-crosslinked quaternary ammonia poly (N-methyl-piperidine-terphenyl and 7-bromo-tri-fluoro-heptanone), denoted as xQAPTF. The crosslinking network inside the membrane can be formed without introducing additional crosslinking agents, and can effectively limit the membrane swelling degree in water (only 4% at 80oC). More importantly, the xQAPTF membranes exhibit excellent mechanical strength and flexibility even after multiple all-wet-all-dry cycles. Under the dry-wet alternating condition (RH repeatedly switched between 100% and 50%), the APEFC using xQAPTF membrane run stably, with the cell voltage switching accordingly and steadily. Such a unique quality of APE membranes has so far not been reported in the literature, which strongly enhances the practicality of APEs, as well as the APEFC and relevant technologies.

Metal ions-assisted construction of SiO2/MXene/Fe3O4 aerogel as multifunctional electromagnetic wave absorbing material

Advanced electromagnetic wave absorbing materials are developing towards the directions of lightweight, thin thickness, broad absorption bandwidth, and multifunction. MXene, as a new type of two-dimensional material, has received widespread attention, but it is necessary to address the impedance mismatch problem caused by its high conductivity. In this work, Fe3O4/MXene composite aerogel is prepared by metal ion-assisted crosslinking method without adding additional crosslinking agents. And a layer of hydrophobic fumed silica is further sprayed on the aerogel. Benefiting from the magneto-electric synergistic effect and the porous structure, SiO2/MXene/Fe3O4 aerogels shows excellent electromagnetic wave absorption performances, achieving a quite broad absorption bandwidth up to 8.8 GHz at an extremely thin thickness of 1 mm. The hybrid aerogel also shows superhydrophobic and thermal insulation properties, which are conducive to improving the resistance to harsh environments and thus endow the absorbers with a long service time.

Comparative Assessment of Novel Collagen Cross-linking Agents on Push-out Bond Strength of Two Different Sealers: An In Vitro Study.

To assess the push-out bond strength and tubular penetration of resin-based and bioceramic sealers after employing two collagen cross-linking agents, namely, cashew nut shell liquid (CNSL) and epigallocatechin-3-gallate (EGCG) on sodium hypochlorite treated root canal dentin. Fifty human permanent mandibular premolars selected were decoronated at CEJ, this was followed by cleaning and shaping protocols, root canals were enlarged up to 20 sizes with 6% taper and were randomly divided into the following 5 groups with 10 samples each based on the cross-linking agent and the sealer: • Group I: Irrigation with saline (control). • Group II: Irrigation with cashew nut shell liquid followed by bioceramic sealer obturation. • Group III: Irrigation with cashew nut shell liquid followed by resin-based sealer obturation. • Group IV: Irrigation with EGCG followed by bioceramic sealer obturation. • Group V: Irrigation with EGCG followed by resin-based sealer obturation. Five specimens in each group were evaluated for push-out bond strength with the universal testing machine while the remaining five specimens in each group were evaluated for depth of sealer penetration by a scanning electron microscope (SEM). The data was recorded, tabulated, and statistically analyzed. The push-out bond strength was found to be maximum in the apical region in all the five groups followed by the middle third and coronal region. The maximum push-out bond strength was seen in group II followed by groups III and IV, and least in group V. The mean depth of tubular penetration of sealers was found to be effective in the coronal portion followed by the middle third while the apical third region showed the least depth penetration of sealers into the tubules. The maximum penetration of sealers was revealed in group V followed by groups III and IV, and least in group II. Within the limitations of this study, it can be concluded that push-out bond strength was found to the maximum in specimens irrigated with cashew nut shell liquid and obturated with bioceramic sealer. The maximum push-out bond strength was seen in the apical third of all root canals followed by the middle and coronal region. The scanning microscopic analysis revealed maximum mean tubular penetration in the coronal portion followed by the middle third and apical third. A greater penetration was seen in specimens irrigated with EGCG and obturated with hybrid sealer. Selection of sealers plays a pivotal role in the success of endodontic therapy. Leakage-related issues can compromise the bond strength enhancing the bond strength can be achieved through the addition of cross-linking agents.

Highly Branched Tannin-Tris(2-aminoethyl)amine-Urea Wood Adhesives.

Condensed tannin copolymerized with hyperbranched tris(2-aminoethyl)amine-urea formed by amine-amido deamination yields a particleboard thermosetting adhesive without any aldehydes satisfying the requirements of relevant standards for the particleboard internal bond strength. The tannin-triamine-urea cures well at 180 °C, a relatively low temperature for today's particleboard hot pressing. As aldehydes were not used, the formaldehyde emission was found to be zero, not even in traces due to the heating of wood. The effect is ascribed to the presence of many reactive sites, such as amide, amino, and phenolic groups belonging to the three reagents used. The tannin appears to function as an additional cross-linking agent, almost a nucleating agent, for the triamine-urea hyperbranched oligomers. Chemical analysis by MALDI ToF and 13C NMR has shown that the predominant cross-linking reaction is that of the substitution of the tannin phenolic hydroxyls by the amino groups of the triamine. The reaction of tannin with the still-free amide groups of urea is rather rare, but it may occur with the rarer tannin flavonoid units in which the heterocyclic ring is opened. Due to the temperature gradient between the surfaces and the board core in the particleboard during hot pressing, the type and the relative balance of covalent and ionic bonds in the resin structure may differ in the surfaces and the board core.

Stimuli-responsive injectable chitosan-based hydrogels for controlled drug delivery systems.

In the last decade, injectable hydrogels have attracted a lot of attention due to their excellent functional properties in the field of drug delivery for precise, non-invasive and focused tissue locations. Therefore, designing drug delivery systems (DDS) responsive to hydrogel stimuli to release a drug to an external stimulus with various advantages, can be very challenging. Due to their biocompatibility, mucosal adhesion, and hemostatic activity, chitosan (Chitosan)-based hydrogels offer a lot of potential for tissue engineering and drug delivery. It can be difficult to manage the structure of these stimuli-responsive CS hydrogels or they may require additional crosslinking agents, such as hydrogels with dual pH and thermo-responsiveness. Therefore, it is crucial to create these hydrogels for medicinal applications.

Thermosensitive Hydrogels and Advances in Their Application in Disease Therapy

Thermosensitive hydrogels, having unique sol–gel transition properties, have recently received special research attention. These hydrogels exhibit a phase transition near body temperature. This feature is the key to their applications in human medicine. In addition, hydrogels can quickly gel at the application site with simple temperature stimulation and without additional organic solvents, cross-linking agents, or external equipment, and the loaded drugs can be retained locally to improve the local drug concentration and avoid unexpected toxicity or side effects caused by systemic administration. All of these features have led to thermosensitive hydrogels being some of the most promising and practical drug delivery systems. In this paper, we review thermosensitive hydrogel materials with biomedical application potential, including natural and synthetic materials. We describe their structural characteristics and gelation mechanism and briefly summarize the mechanism of drug release from thermosensitive hydrogels. Our focus in this review was to summarize the application of thermosensitive hydrogels in disease treatment, including the postoperative recurrence of tumors, the delivery of vaccines, the prevention of postoperative adhesions, the treatment of nervous system diseases via nasal brain targeting, wound healing, and osteoarthritis treatment.

Magnetic cryogels as a shape-selective and customizable platform for hyperthermia-mediated drug delivery

Cryogels consisting of polyvinyl alcohol and iron (II, III) oxide magnetic nanoparticles coated with a model drug—acetaminophen, were developed as a tunable platform for thermally triggered drug release, based on shape-selective heat transfer. Two different shapes of cryogels; discs and spherical caps, were formed via adding polymer-nanoparticle-drug mixtures into 3D printed molds, followed by freeze-thawing five times. No additional chemical crosslinking agents were used for gel formation and the iron oxide nanoparticles were coated with acetaminophen using only citric acid as a hydrogen-bonding linker. The two gel shapes displayed varying levels of acetaminophen release within 42–50 °C, which are ideal temperatures for hyperthermia induced drug delivery. The amount and time of drug-release were shown to be tunable by changing the temperature of the medium and the shape of the gels, while keeping all other factors (ex. gel volume, surface area, polymer/nanoparticle concentrations and drug-loading) constant. The discs displayed higher drug release at all temperatures while being particularly effective at lower temperatures (42–46 °C), in contrast to the spherical caps, which were more effective at higher temperatures (48–50 °C). Magnetic hyperthermia-mediated thermal imaging and temperature profiling studies revealed starkly different heat transfer behavior from the two shapes of gels. The disc gels retained their structural integrity up to 51 °C, while the spherical caps were stable up to 59 °C, demonstrating shape-dependent robustness. The highly customizable physicochemical features, facile synthesis, biocompatibility and tunable drug release ability of these cryogels offer potential for their application as a low cost, safe and effective platform for hyperthermia-mediated drug delivery, for external applications such as wound care/muscle repair or internal applications such as melanoma treatment.

Improvement of IgA Nephropathy and Kidney Regeneration by Functionalized Hyaluronic Acid and Gelatin Hydrogel.

Immunoglobulin A (IgA) nephropathy (IgAN) is one of an important cause of progressive kidney disease and occurs when IgA settles in the kidney resulted in disrupts kidney's ability to filter waste and excess water. Hydrogels are promising material for medical applications owing to their excellent adaptability and filling ability. Herein, we proposed a hyaluronic acid/gelatin (CHO-HA/Gel-NH2) bioactive hydrogel as a cell carrier for therapeutic kidney regeneration in IgAN. CHO-HA/Gel-NH2 hydrogel was fabricated by Schiff-base reaction without any additional crosslinking agents. The hydrogel concentrations and ratios were evaluated to enhance adequate mechanical properties and biocompatibility for further in vivo study. High serum IgA ddY mice kidneys were treated with human urine-derived renal progenitor cells encapsulated in the hydrogel to investigate the improvement of IgA nephropathy and kidney regeneration. The stiffness of the hydrogel was significantly enhanced and could be modulated by altering the concentrations and ratios of hydrogel. CHO-HA/Gel-NH2 at a ratio of 3/7 provided a promising milieu for cells viability and cells proliferation. From week four onwards, there was a significant reduction in blood urea nitrogen and serum creatinine level in Cell/Gel group, as well as well-organized glomeruli and tubules. Moreover, the expression of pro-inflammatory and pro-fibrotic molecules significantly decreased in the Gel/Cell group, whereas anti-inflammatory gene expression was elevated compared to the Cell group. Based on in vivo studies, the renal regenerative ability of the progenitor cells could be further increased by this hydrogel system.

Light-induced synthesis and characterization of “Clickable” polyacrylamide hydrogels

Hydrogels are important three-dimensional network polymers for various technologies ranging from tissue engineering to bio-sensing due to their high water absorption, biocompatibility and non-toxic characteristics. A desirable feature of hydrogels is to possess suitable functionalities for post modification that can support their extended applications. In the present work, we report a facile synthesis of clickable polyacrylamide hydrogel by photopolymerization using acrylamide and propargyl acrylate in the presence of different photoinitiators and in the absence of any additional conventional crosslinking agent under ultraviolet (UV) and visible light. The effect of irradiation time on gel fraction, swelling degree and compressive elasticity was investigated. Thiol-ene, thiol-yne and copper-catalyzed azide-alkyne cycloaddition click functionality of the produced hydrogels were confirmed by using respective fluorescent click components.

Formation and properties of cross-linked polymer films based on biocompatible polymers

Cross-linked polymer films based on polyvinyl alcohol and polyacrylamide have been prepared via radical cross-linking initiated by peroxide containing reactive copolymers. The influence of temperature, nature and concentration of cross-linking agents onto gel-fraction value and properties of polymer films has been studied. Obtained cross-linked polymer films are characterized by improved physico-mechanical properties that depend on the content of peroxide containing copolymer and on the presence of additional cross-linking agent.

A simple and green approach to the preparation of super tough IIR/SWCNTs nanocomposites with tunable and strain responsive electrical conductivity

Abstract Nanocomposites of single-wall carbon nanotubes in isobutylene isoprene rubber (IIR/SWCNTs) were successfully prepared by a simple and green wet process. The traditional melt mixing process and organic solvent dissolution suffered from unable to effectively disperse the SWCNTs of tangled structure, and degradation of polymer molecules, respectively. Our process very well avoided these two problems. The SWCNTs aqueous solutions emulsified by polyoxyethylene octyl phenol ether (OP-10) were firstly mixed and compounded with IIR rubber at a relatively high temperature, followed by the second step of melt compounding process with the addition of cross-linking agent and accelerators. The SWCNTs were dispersed uniformly, and a fine network was constructed in the matrix of the obtained IIR/SWCNTs nanocomposite with a low percolation threshold. With the concentration of SWCNTs as low as 2 phr, the IIR/SWCNTs nanocomposite received an electrical conductivity of 10−6∼10−3 S/cm, and a 71% improvement of tensile strength. By varying the loadings of SWCNTs in a certain range, the tensile strength, electrical conductivity, and dielectric property were found tunable. Besides, the nanocomposites also presented strain responsive specific resistance, excellent elongation (600–740%), and better heat resistance.

Affordable Magnetic Hydrogels Prepared from Biocompatible and Biodegradable Sources.

Magnetic hydrogels composed of poly(vinyl alcohol) (PVA)/water-soluble tricarboxy cellulose (CO)/magnetic fluids (MFs) have been prepared by a freeze–thaw cycle technique. The system designed here combines the renewability and biocompatibility aspects of PVA and CO, as well as the magnetic properties of MFs, thereby offering special properties to the final product with potential applications in medicine. In the first step, the water-soluble CO is synthesized using a one-shot oxidation procedure and then the aqueous solutions of CO are mixed with PVA solutions and magnetic fluids in the absence of any additional cross-linking agent. The magnetic hydrogels were thoroughly investigated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), magnetometry (VSM), and thermogravimetric analysis. The morphological results show an excellent distribution of magnetic particles and CO inside the PVA matrix. The VSM results show that the magnetic hydrogels possess superparamagnetic properties.

Improved water absorption behaviour of experimental hydrophilic vinyl polysiloxane (VPS) impression materials incorporating a crosslinking agent and a novel surfactant

ObjectivesTo study the effects of incorporating a further crosslinking agent and a novel surfactant on the water absorption behaviour of experimental VPS impression materials. MethodsPart 1: The water uptake behaviour of Aquasil-Ultra-Monophase (AqM) was studied gravimetrically in three media (DW, 1%NaOCl and Perform ID), at 23 °C and 37 °C, over a period of one and four-months (n = 5) to gain information on long-term immersion. Part 2: Five experimental materials were formulated: Exp-I and II as hydrophobic and Exp-III-V as hydrophilic, containing an additional cross-linking agent (TFDMSOS) and Rhodasurf CET-2 surfactant. Their water uptake and desorption (both at 23 °C) properties (gravemetrically), solubility, pH and diffusion coefficient (DC) data were compared with three commercial, hydrophilic VPS impression materials, over seven days (n = 5). The results were analysed statistically. ResultsPart 1: Significant differences in water absorbed by AqM were observed in the three media at 23 °C. Aq M had a significantly higher uptake in 2% Perform ID, than in DW and NaOCl. At 37 °C, over four-months the uptake profiles were more enhanced and differed. Part 2: All Exp and commercial materials significantly increased in weight in both media (DW and 1% NaOCl at 23 °C), with differing uptake profiles and non-reached equilibrium. Exp-VPS absorbed significantly less water than commercial-VPS. Desorption of all VPS from both parts was faster than absorption, followed Fickian diffusion kinetics and reached equilibrium within 1–3 days. Desorption DCs for Exp-VPS were higher than commercial materials (10−10 versus 10−11 m2 s−1). The solubility was higher in 1% NaOCl compared to DW. The pH of DW after immersion of samples significantly increased compared to 1% NaOCl. SignificanceThe incorporation of novel cross-linking agent, TFDMSOS and non-ionic surfactant, Rhodasurf CET-2, (ethoxylated-cetyl-oleyl alcohol) improved the dimensional stability of hydrophilic Exp-VPS in DW and 1% NaOCl. These materials merit further research in producing accurate casts of the patient’s anatomy following disinfection.