Interpenetrating Polymer Networks Research Articles

Synthesis and performance study of novel antibacterial and anticorrosive polyurethane IPN

Polyaniline has been extensively used for the corrosion protection of polymeric materials. However, there have been few studies on its combined antimicrobial activity when used in combination with silver molybdate. In this study, we synthesized silver molybdate (Ag2MoO4) crystals using a homogeneous precipitation method. Polyaniline-dodecylbenzenesulfonic acid/castor oil(PANI-DBSA/CO) mixtures were prepared in an encapsulated state by in situ polymerisation. Subsequently, PANI/Ag2MoO4-PU interpenetrating polymer network(IPN) composite coatings(P/A-PU) were produced by dispersing Ag2MoO4 and PANI-DBSA/CO in polyurethane using ultrasonic dispersion. The composite coatings were characterized using Fourier transform infrared spectroscopy(FTIR), X-ray diffraction analysis(XRD), and transmission electron microscopy(TEM). The study confirmed that composite coatings with uniformly dispersed nanoparticles of PANI and Ag2MoO4 encapsulated by CO and epoxy resin E-44 grease exhibit improved physico-mechanical characteristics. The research also evaluated the effect of nanoparticles on the corrosion behaviour of the coatings using electrochemical impedance spectroscopy and kinetic potential polarisation experiments. The study investigated the antimicrobial properties of P/A-PU composite coatings on Escherichia coli(E.coli) and Staphylococcus aureus(S.aureus) by conducting bacterial growth curves, protein leakage, and fluorescence staining experiments. The aim was to establish a causal connection between the coated surfaces and the observed antimicrobial properties. The study demonstrated that incorporating IPN of polyaniline polyurethane into the coating composites improved their anticorrosive properties. Furthermore, the addition of silver molybdate at a mass ratio of 0.3 % resulted in a remarkable 99 % antimicrobial activity against E.coli and S.aureus.

Characterization of hydrogel beads constructed from gelatinized lotus rhizome starch and sodium alginate by calcium cross-linking

The purpose of this study was to construct calcium cross-linked gelatinized lotus rhizome starch (LRS)/sodium alginate (SA) hydrogel beads of adjustable quality and to reduce the digestibility of gelatinized starch. LRS was mixed with SA, gelatinized by heating and subsequently cross-linked with Ca2+ to form hydrogel beads. The digestibility of the gelatinized LRS could be adjusted by changing the dose of SA in the hydrogel beads. When the LRS/SA ratio was 4/6, the rapidly digested starch (RDS) content in the beads was reduced by 26.9% compared with gelatinized LRS alone, whereas the slowly digested starch (SDS) and resistant starch (RS) contents increased by 12.3-fold and 2.3-fold, respectively. In addition, the water distribution in the Ca2+-crosslinked LRS/SA hydrogel bead samples also showed an SA dose dependence. With increasing SA concentration, the ability of the hydrogel beads to immobilize water increased. The diffusion of Ca2+ into the interpenetrating polymer network that was prepared with gelatinized LRS and SA gradually resulted in gelation dominated by ion bonds, leading to the heterogeneous microstructure of the hydrogel beads, which also involved intermolecular hydrogen bond interactions. Overall, the present study suggested a strategy for developing novel LRS hydrogel bead systems for quality control and gelatinized starch digestibility downregulation by adjusting the SA dose, which provided insights for the innovation of personalized and convenient starchy products in the food industry.

Effect of catalysts on the mechanical, thermal, and adhesive properties of polyrotaxane-modified epoxy resin

Polyrotaxane (PR) is a supramolecular polymer, in which an axial polymer extends through multiple cyclic molecules. PR specifically comprises polyethylene glycol, α-cyclodextrin, and adamantane as the axial polymer, cyclic molecule, and terminal blocking group, respectively. It is a useful stress-relaxing material because the cyclic polymers can freely slide and rotate in cyclic motions on the axial polymer. In this study, diglycidyl ether of bisphenol A (DGEBA) epoxy resin cured with phenolic resin (PN) was blended with PR, which has methacryl groups at the ends of side chains of the cyclic molecules, as a toughness modifier. The effect of the methacryl group polymerization catalyst (DCP) on the cured properties of epoxy resin was reported. PR was homogeneously dispersed in the DGEBA/PN resin matrix. Increasing the PR concentration significantly improved the toughness, impact resistance, and adhesive properties of the DGEBA/PN/PR alloy. Moreover, adding DCP resulted in an increase in the glass transition temperature due to the decreased molecular mobility of the network. This phenomenon was attributed to the synergistic effect of the formation of an interpenetrating polymer network, which is an entangled network of the curing reaction of the DGEBA/PN resin and polymerization of PR, and the intermolecular hydrogen bonds between carbonyl and hydroxyl groups of PR and hydroxyl groups of the DGEBA/PN resin. In contrast, the increased interfacial adhesion between PR and the DGEBA/PN did not result in significant improvement of flexural properties.

Exploiting light-based 3D-printing for the fabrication of mechanically enhanced, patient-specific aortic grafts

Despite polyester vascular grafts being routinely used in life-saving aortic aneurysm surgeries, they are less compliant than the healthy, native human aorta. This mismatch in mechanical behaviour has been associated with disruption of haemodynamics contributing to several long-term cardiovascular complications. Moreover, current fabrication approaches mean that opportunities to personalise grafts to the individual anatomical features are limited. Various modifications to graft design have been investigated to overcome such limitations; yet optimal graft functionality remains to be achieved. This study reports on the development and characterisation of an alternative vascular graft material. An alginate:PEGDA (AL:PE) interpenetrating polymer network (IPN) hydrogel has been produced with uniaxial tensile tests revealing similar strength and stiffness (0.39 ± 0.05 MPa and 1.61 ± 0.19 MPa, respectively) to the human aorta. Moreover, AL:PE tubular conduits of similar geometrical dimensions to segments of the aorta were produced, either via conventional moulding methods or stereolithography (SLA) 3D-printing. While both fabrication methods successfully demonstrated AL:PE hydrogel production, SLA 3D-printing was more easily adaptable to the fabrication of complex structures without the need of specific moulds or further post-processing. Additionally, most 3D-printed AL:PE hydrogel tubular conduits sustained, without failure, compression up to 50% their outer diameter and returned to their original shape upon load removal, thereby exhibiting promising behaviour that could withstand pulsatile pressure in vivo. Overall, these results suggest that this AL:PE IPN hydrogel formulation in combination with 3D-printing, has great potential for accelerating progress towards personalised and mechanically-matched aortic grafts.

A gel-based electrochromic device towards fast response and high coloration efficiency for low-power consumption smart window applications

Immobilization of viologen derivatives in the solid electrolyte can improve significantly the electrochromic performance and stability of a viologen-based electrochromic device (ECD). Here, we successfully developed a bis(3-hydroxyethyl) viologen dibromide-immobilized PVA/CMC/Borax gel-based ECD with high coloration efficiency, fast response, and long optical memory through an easy immobilization strategy. The bis(3-hydroxyethyl) viologen dibromide was immobilized in a borax-crosslinked polyvinyl alcohol/carboxymethyl cellulose (PVA/CMC/Borax) gel electrolyte. With borate crosslinking, PVA and CMC existed in an interpenetrating polymer network (IPN), which lowers the crystallinity and glass transition temperatures of each polymer. This increase in mobility of ions through gel electrolyte leads to fast response and high coloration of ECD. The ECD exhibited fast response and high contrast ratio with a maximum contrast ratio of 98% with applying −2.5 V for a very short time of 10 s. The ECD showed a high coloration efficiency of 1280 cm2 C−1 at a switching voltage of −2.5 V, which is a high coloration efficiency value for viologen-based ECD reported so far.

Macroporous, Highly Hygroscopic, and Leakage-Free Composites for Efficient Atmospheric Water Harvesting.

Hygroscopic composites based on hygroscopic salts and hydrogels are promising for atmospheric water harvesting (AWH), but their relatively low water production and possible salt leakage hinder real applications. Here, we report highly hygroscopic and leakage-free composites from loading LiCl into emulsion-templated sodium alginate and poly(vinyl alcohol) hydrogels with macroporous structures and interpenetrating polymer networks. The resulting composites exhibited an enhanced moisture uptake (up to 3.4 g g-1) and leakage-free behavior even at an extremely high relative humidity (RH) of 90%. Moreover, the composites showed accelerated adsorption, with high adsorption (0.803 g g-1 water at 25 °C and 90% RH within 1 h) and desorption due to the emulsion-templated, highly interconnected macropores. The hygroscopic composites obtained 1.12 g g-1 water per adsorption-desorption collection cycle and showed high reusability, without obvious deterioration in adsorption, desorption, and collection after 10 cycles. With the presence of carbon nanotubes, solar-driven AWH could be realized, without the requirement of additional energy. The highly hygroscopic and leakage-free composites with enhanced and accelerated adsorption and desorption are excellent candidates for efficient AWH.

Photonic Interpenetrating Polymer Network Fibers Comprising Intertwined Solid-State Cholesteric Liquid Crystal and Polyelectrolyte Networks for Sensor Applications.

Uniform-sized photonic interpenetrating polymer network (IPN) fibers comprising intertwined solid-state cholesteric liquid crystal (CLCsolid) and anionic poly(acrylic acid) (PAA) or cationic poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) networks (photonic IPNPAA or IPNPDMAEMA fibers) were developed for sensor applications. IPNPAA or IPNPDMAEMA fibers with a perfect photonic structure were fabricated inside Teflon tube templates without any treatments for realizing a planar orientation in those fibers. The dominant wavelength of the photonic color from a photograph taken with a cellular phone was used to measure the photonic color change. Photonic IPNPAA fibers treated with KOH (IPNKOH fibers) were used for sensing humidity and divalent metal ions. The linear ranges for relative humidity and Ca2+ detection were 21-92% and 0.5-3.5 mM, and their limits of detection (LODs) were 7.86% and 0.07 mM, respectively. The photonic IPNPAA (or IPNPDMAEMA) fiber immobilized with urease (IPNPAA-urease) (or glucose oxidase (IPNPDMAEMA-GOx)) was used for urea (or glucose) biosensor application. The photonic IPNPAA-urease (or IPNPDMAEMA-GOx) fiber was red-shifted in response to urea (or glucose) in the linear range of 10-60 mM (or 2-16 mM) with an LOD of 2.54 mM (or 0.76 mM). These photonic IPN fibers are promising because of their easy fabrication and miniaturization, battery-free device, cost-effectiveness, and visual detection without using sophisticated analytical instruments. The developed photonic IPN fibers provide new possibilities for the widespread use of photonic sensors in cutting-edge wearable technology and beyond.

Fast skin healing chitosan/PEO hydrogels: In vitro and in vivo studies

Due to its outstanding qualities, particularly when it takes the shape of hydrogels, chitosan is a well-known biological macromolecule with many applications. When chitosan hydrogels are modified with other polymers, the desirable function as skin regeneration hydrogels is compromised; nevertheless, the mechanical properties can be improved, which is crucial for commercialization. In this study, for the first time, bimetallic zinc silver metal-organic frameworks (ZAg MOF) loaded with ascorbic acid were added to chitosan/polyethylene oxide (PEO) based interpenetrating polymer network (IPN) hydrogels that were crosslinked with biotin to improve their antimicrobial activity, mechanical characteristics, and sustainable treatment of wounds. Significant changes in the microstructure, hydrophilicity level, and mechanical properties were noticed. Ascorbic acid release patterns were upregulated in an acidic environment pH (5.5) that mimics the initial wound pH. Impressive cell viability (98 %), antimicrobial properties, and almost full skin healing in a short time were achieved for the non-replaceable chitosan/PEO developed hydrogels. Enhancing the wound healing of the treated animals using the prepared CS/PEO hydrogel dressing was found to be a result of the inhibition of dermal inflammation via decreasing IL-1β, suppressing ECM degradation (MMP9), stimulating proliferation through upregulation of TGF-β and increasing ECM synthesis as it elevates collagen 1 and α-SMA contents. The findings support the implementation of developed hydrogels as antimicrobial hydrogels dressing for fast skin regeneration.

Multifunctional graft-IPN hydrogels of cellulose nanofibers and poly(N-isopropyl acrylamide) via silver-promoted decarboxylative radical polymerization

Interpenetrating polymer networks (IPNs) have emerged as innovative materials for a wide range of applications. Owing to the crosslinked structure of their polymer components, IPNs exhibit superior properties relative to their single component counterparts. Here, we report a new class of multifunctional graft-interpenetrating polymer network (graft-IPN) hydrogel composites of poly(N-isopropylacrylamide) (PNIPAM) grafted onto cellulose nanofibers (CNFs) via silver(I)-promoted decarboxylative polymerization. This novel approach involves the Ag-promoted graft polymerization and the crosslinking of PNIPAM in the CNF network, forming a hybrid of semi-IPN and graft-copolymer hydrogel. Different from conventional PNIPAM-CNF IPNs, the CNFs in graft-IPN hydrogels form an interconnected network as a result of crosslinking between neighboring grafted PNIPAM. Silver nanoparticles (AgNPs) are also formed in situ in the graft-IPN hydrogel matrix, demonstrating the dual functionality of silver as both a catalyst in the polymerization and an eventual antibacterial agent in the hydrogel. The network structure of graft-IPN hydrogels can be controlled by crosslinker and Ag(I) concentration, therefore modulating their thermo-responsive, mechanical, and swelling properties. The grafting of PNIPAM from CNFs shifts the volume phase transition to 36 °C and significantly improves the mechanical strength and swelling capacity of the hydrogels. Ultimately, this work demonstrates the excellent potential of these multifunctional graft-IPN hydrogels with controllable thermosensitivity, mechanical strength and anti-microbial activity as engineered biomaterials for advanced applications in biomedicine, engineering, and industry.

Fabrication and Characterization of Quad-Component Bioinspired Hydrogels to Model Elevated Fibrin Levels in Central Nervous Tissue Scaffolds.

Multicomponent interpenetrating polymer network (mIPN) hydrogels are promising tissue-engineering scaffolds that could closely resemble key characteristics of native tissues. The mechanical and biochemical properties of mIPNs can be finely controlled to mimic key features of target cellular microenvironments, regulating cell-matrix interactions. In this work, we fabricated hydrogels made of collagen type I (Col I), fibrin, hyaluronic acid (HA), and poly (ethylene glycol) diacrylate (PEGDA) using a network-by-network fabrication approach. With these mIPNs, we aimed to develop a biomaterial platform that supports the in vitro culture of human astrocytes and potentially serves to assess the effects of the abnormal deposition of fibrin in cortex tissue and simulate key aspects in the progression of neuroinflammation typically found in human pathologies such as Alzheimer's disease (AD), Parkinson's disease (PD), and tissue trauma. Our resulting hydrogels closely resembled the complex modulus of AD human brain cortex tissue (~7.35 kPa), promoting cell spreading while allowing for the modulation of fibrin and hyaluronic acid levels. The individual networks and their microarchitecture were evaluated using confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). Human astrocytes were encapsulated in mIPNs, and negligible cytotoxicity was observed 24 h after the cell encapsulation.

3D printing of cyanate ester resins with interpenetration networks for enhanced thermal and mechanical properties

AbstractCyanate ester (PT‐30) resin possesses exceptional thermal and mechanical properties, including high heat distortion temperature, high glass transition temperature (Tg), and outstanding mechanical characteristics. Conversely, the Tg of the homopolymer of tris(2‐hydroxyethyl)isocyanurate triacrylate (T‐acrylate) surpasses that of other acrylates. The combination of PT‐30 and T‐acrylate results in the formation of an interpenetrating polymer network (IPN) through a dual curing mechanism. Furthermore, the combination of these two polymers enables the tuning of rheology for shear thinning behavior for Ink Extrusion 3D printing technology by adjusting the amount of photoinitiator and rheological modifier. Here, 3D printable ink was formulated using PT‐30, T‐acrylate with a higher Tg, a photoinitiator, and a powdered rheological additive. The printed structures underwent a dual‐curing process involving exposure to UV light and thermal curing. Thermomechanical properties of the printed samples were characterized using dynamic mechanical analysis, thermogravimetric analysis, and tensile testing. The successful formation of an IPN structure through the polymerization of T‐acrylate and PT‐30 was observed, resulting in improved mechanical properties and an elevated Tg. The Fourier transform infrared spectroscopy analysis verified the formation of cross‐linked samples. Overall, this study demonstrates the feasibility of Ink Extrusion 3D printing, using a cyanate ester resin and tris(2‐hydroxyethyl)isocyanurate triacrylate with a dual‐curing mechanism. The enhanced mechanical properties at elevated temperatures (~80% retention of room temperature tensile strength at 200°C for sample with 70/30 wt%) and high Tg of 349 ± 3°C for printed structures shown in this study make them suitable for high‐performance structural applications in industries such as aerospace, defense, and microelectronics.

Organo-inorganic hybrid IPN sourced porous carbons and their lead decontamination perspectives

The present communication is about generation of porous carbons through sacrificial template route, from organo-inorganic hybrid interpenetrating polymer networks (IPN's) and their use as a remediation tool for the removal of lead ions from contaminated water. The hybrid IPN's between phenol-formaldehyde (PF) polymer and silica were formed through sequential IPN formation route, in which, silica network was formed first through sol-gel process involving tetraethoxysilane (TEOS) dispersed in phenolic resin followed by thermal crosslinking of the later. The resulting PF/SiO2 IPNs were transformed to C/SiO2 composites through carbonization at 1000 °C under inert atmosphere with silica contents ranging from 10 to 70 %. The silica phase was sacrificed through hydrogen fluoride (HF) leaching to obtain porous carbons, which were further chemically activated with KOH. The derived porous carbons had hierarchical open pore geometry with majority of the pores belonging to the meso category. The carbons were employed to scavenge lead (Pb2+) ions from aqueous effluents and a maximum uptake of 177.3 mg of Pb2+ ions per gram of the adsorbent, was achieved with the present carbons. The adsorption was studied with standard adsorption models, such as Langmuir and Freundlich, of which a better compliance with Langmuir model was noted. Adsorption between the PFSiC carbons and Pb2+ ions obeyed second order kinetics.

Free-standing and flexible polyvinyl alcohol-sodium alginate-polypyrrole electrodes based on interpenetrating network hydrogels

Flexible supercapacitors (FSCs) have attracted much attention due to their strong mechanical flexibility, wearability and portability, which greatly rely on the employed flexible electrodes. The conductive polymer hydrogels with excellent flexibility, processability and capacitive performance are one of the most promising candidates, which are still limited by their poor mechanical properties. Constructing robust interpenetrating polymer networks (IPN) is an effective approach to promote their mechanical properties. Herein, interpenetrating polyvinyl alcohol (PVA)-sodium alginate (SA)-polypyrrole (PPy) hydrogels are prepared by the freeze–thaw and in-situ polymerization method. The IPN structure composed of PVA and SA not only enhances the mechanical properties of hydrogels, but also provides substantial active sites for electrochemical reactions. Moreover, the hydrogen-bonding interaction between different components in the PVA-SA-PPy hydrogel boosts the charge/ion transfer. The optimal PVA-SA-PPy hydrogels show an elongation at break of 380 %, a tensile strength of 1.5 MPa, and a specific capacitance of 2646 mF cm−2 at 2 mA cm−2. The symmetric PVA-SA-PPy FSCs show an energy density of 96.7 μWh cm−2 at a power density of 999.9 μW cm−2, and the capacitance retention is 66.3 % after 10,000 cycles. These exceptional mechanical and electrochemical properties make the PVA-SA-PPy hydrogels a promising candidate for FSCs.

A low-density polymer/CrMnFeCoNi composite with high strength and high damping capacity

A novel damping composite was successfully prepared by taking a porous CrMnFeCoNi high-entropy shape memory alloy as the skeleton and filling its pores with the composite composed of carbon nanotubes and polyurethane/epoxy interpenetrating polymer networks. When the porosity, pore size and CNT loading are 80 %, 1.2 mm and 2 wt%, respectively, the compressive strength, elastic modulus and energy absorption capacity of the composite are 35.7 MPa, 1.31 GPa and 23.1 MJ/m3 (ε = 65 %), respectively. Furthermore, it has a mere density of 2.525 g/cm3. Its loss factor is greater than 0.093 and can reach a maximum of 0.145 within the temperature and frequency range of 20 ∼ 150 ℃ and 0.1 ∼ 200 Hz. A triple-phase micromechanical model was utilized to explore the damping mechanism of composites. Results indicate the coupling of multiple damping mechanisms is the reason for the high ground-state damping of composites, and interface damping is the primary damping mechanism. The superposition of the ε → γ reverse martensite transformation peak of the CrMnFeCoNi HESMA skeleton and the glass transition peak of the CNTs/polymer composite matrix realizes the wide damping temperature range of the composite.

3D printing of gellan-dextran methacrylate IPNs in glycerol and their bioadhesion by RGD derivatives.

The ever-growing need for new tissue and organ replacement approaches paved the way for tissue engineering. Successful tissue regeneration requires an appropriate scaffold, which allows cell adhesion and provides mechanical support during tissue repair. In this light, an interpenetrating polymer network (IPN) system based on biocompatible polysaccharides, dextran (Dex) and gellan (Ge), was designed and proposed as a surface that facilitates cell adhesion in tissue engineering applications. The new matrix was developed in glycerol, an unconventional solvent, before the chemical functionalization of the polymer backbone, which provides the system with enhanced properties, such as increased stiffness and bioadhesiveness. Dex was modified introducing methacrylic groups, which are known to be sensitive to UV light. At the same time, Ge was functionalized with RGD moieties, known as promoters for cell adhesion. The printability of the systems was evaluated by exploiting the ability of glycerol to act as a co-initiator in the process, speeding up the kinetics of crosslinking. Following semi-IPNs formation, the solvent was removed by extensive solvent exchange with HEPES and CaCl2 , leading to conversion into IPNs due to the ionic gelation of Ge chains. Mechanical properties were investigated and IPNs ability to promote osteoblasts adhesion was evaluated on thin-layer, 3D-printed disk films. Our results show a significant increase in adhesion on hydrogels decorated with RGD moieties, where osteoblasts adopted the spindle-shaped morphology typical of adherent mesenchymal cells. Our findings support the use of RGD-decorated Ge/Dex IPNs as new matrices able to support and facilitate cell adhesion in the perspective of bone tissue regeneration.

Rapid tooling for rubber extrusion molding by digital light processing 3D printing with dual curable vitrimers

AbstractFor the manufacture of extrusion dies, three‐dimensional (3D) printing with photopolymers offers numerous advantages including flexibility, high surface quality, decent build speed, low costs and a reduced amount of waste. However, the majority of photocurable resins used in vat photopolymerization 3D printing rely on acrylates, which entail 3D‐printed objects with poor mechanical properties. In particular, the high brittleness limits their application in rapid tooling, for which tough materials with high glass transition temperatures (Tg) are required. In the present study, we highlight the use of dual curable acrylate‐epoxy resins with dynamic covalent bonds for the direct fabrication of extrusion dies. During digital light processing (DLP) 3D printing the acrylate network is formed, whose toughness and thermal stability are significantly enhanced by the thermoactivated formation of a second network. By following a postbaking procedure, aminoglycidiyl monomers are cured with an anhydride hardener bearing bulky norbornene groups yielding interpenetrating polymer networks with a Tg > 100°C. The tertiary amine groups present in the structure of the aminoglycidyl derivatives do not only accelerate the ring‐opening reaction but also act as internal catalysts and activate bond exchange reactions between free –OH groups and ester moieties available in the photopolymer. This is confirmed by rheometer studies showing a distinctive stress relaxation at elevated temperature and giving rise to a possible reprocessability of the 3D‐printed dies. With a selected resin formulation, a set of dies is printed by DLP 3D printing, with which a highly filled rubber compound is successfully extruded. The results clearly show that dual curable resins with dynamic covalent bonds are a promising class of material for rapid tooling and pave the way towards a customized and convenient fabrication of extrusion dies for rubber processing.

Experimental comparative study of a novel drug-eluting arteriovenous graft in a sheep model.

Arteriovenous (AV) grafts often develop severe complications of stenosis due to neointimal proliferation that occurs either at the venous anastomosis site or at the outflow receiving vein. This study compares primary patency during 12 months of follow up for a new experimental Biomodics© interpenetrating polymer network (IPN) drug-eluting graft prototype with state-of-the-art GORE® ACUSEAL (ACUSEAL) in an AV graft model in sheep. An end-to-end bypass from the common carotid artery to the jugularis vein was performed bilaterally in 12 sheep. The usage of ACUSEAL or the IPN, both 6.0 mm in diameter, was determined via randomization. The sheep were followed up every 4 weeks with ultrasonic duplex scanning to determine patency; the experienced observer was blinded to the randomization. One sheep died after 11 days, and the final sample accordingly consisted of 11 animals. When comparing neointimal hyperplasia after 12 months in the two grafts, Fisher's exact test showed a significant difference with none out of 11 in the IPN grafts and 9 out of 11 in the ACUSEAL graft (p < 0.001). However, the Biomodics© IPN exhibited severe deterioration over time. Almost all of the grafts occluded during the 12 months of follow up. Although the zwitterion-bounded interpenetrating drug eluting polymer network showed signs to impair neointimal hyperplasia and thrombosis, age-related degeneration hindered demonstrating a potential improvement in patency.

Production of Sequential Interpenetrating Polymer Networks from Ximenia americana Seed Oil-based Polyurethanes and Polystyrene

Interpenetrating polymer network are combinations of two or more polymer in network form. The objective of this paper was to evaluate the production and characterization of sequential polyurethane-polystyrene interpenetrating polymer networks from different diisocyanates and varied styrene content using Ximenia americana seed oil as base material. The polymer networks were characterized for their Tensile, Swelling and Thermal properties. The tensile strength and tensile modulus for MDPU-1.50-PS polymer networks, 57.86 ±5.42 - 422.85±15.25 MPa and 2.26±0.91 - 11.08±4.21 MPa respectively are higher than the values represented for HDPU-1.50-PS and TDPU-1.50-PS polymer networks, but the latter polymer networks are higher in values for elongation at break than the former. This is also corroborated by the swelling mass ratio (qm) with values for HDPU-1.50-PS and TDPU-1.50-PS networks higher than those for MDPU-1.50-PS, consistent with lower polystyrene crosslinks in the former polymer networks. Thermal studies present HDPU-1.50-PS-20 as the most stable network at 10% degradation, but at higher degradation temperatures MDPU-1.50-PS-20 polymer network shows stability up to 6000C with 19.40g residual weight of char polymer. This study shows that derivatised Ximenia americana seed oil is suitable as starting material for preparation of an interpenetrating polymer network.

Low-temperature crosslinking characteristics of interpenetrating polymer networks with dual-curable amine-based blocked isocyanate for automotive 1 K clearcoats

Interpenetrating polymer network (IPN) clearcoat systems were developed using two distinct thermal crosslinking reactions: urethane formation reaction and free radical polymerization. Specifically, an amine-based dual-curable blocked isocyanate crosslinker (BITBEMA) was employed to establish additional independent networks within IPNs by utilizing dissociated blocking groups through free radical polymerization. To validate the formation of the IPN and its suitability for a low-temperature curing process, the thermal deblocking characteristics and crosslinking dynamics of the dual-curable 1 K clearcoat were confirmed via various experimental methods, including rheological tests, thermogravimetric analyses, dynamic mechanical analyses, and nano-indentation tests. The influence of the IPNs on the crosslinking characteristics was examined and compared with clearcoat systems featuring only a urethane formation network. Both semi-IPN and full-IPN configurations demonstrated enhanced thermal and mechanical properties in contrast to the mono-curable 1 K clearcoat system, especially at low curing temperatures.

Biobased Interpenetrating Polymer Network Membranes for Sustainable Molecular Sieving.

There is an urgent need for sustainable alternatives to fossil-based polymer materials. Through nanodomain engineering, we developed, without using toxic cross-linking agents, interpenetrating biopolymer network membranes from natural compounds that have opposing polarity in water. Agarose and natural rubber latex were consecutively self-assembled and self-cross-linked to form patchlike nanodomains. Both nano-Fourier transform infrared (nano-FTIR) spectroscopy and computational methods revealed the biopolymers' molecular-level entanglement. The membranes exhibited excellent solvent resistance and offered tunable molecular sieving. We demonstrated control over separation performance in the range of 227-623 g mol-1 via two methodologies: adjusting the molecular composition of the membranes and activating them in water. A carcinogenic impurity at a concentration of 5 ppm, which corresponds to the threshold of toxicological concern, was successfully purged at a negligible 0.56% pharmaceutical loss. The biodegradable nature of the membranes enables an environmentally friendly end-of-life phase; therefore, the membranes have a sustainable lifecycle from cradle to grave.