Formation Of Interpenetrating Polymer Networks Research Articles

Gelling and bile acid binding properties of gelatin-alginate gels with interpenetrating polymer networks by double cross-linking

Interpenetrating polymer network (IPN) is an effective method to improve functional properties of hydrogels by forming cross-linking networks. In this study, the gelatin-alginate gels formed by the combination of enzymatic and ionic cross-linking were called IPN gels. Meanwhile, the gels with the treatment of only transglutaminase (TG) or Ca2+ were named as G-semi-IPN and A-semi-IPN, respectively. The formation of semi-IPN and IPN was confirmed by studies on rheology, thermodynamics and micro-morphology. The results showed that the IPN gels had improved gelling properties and structural stability. The functional properties of different gelatin-alginate gels were also investigated. It was firstly found that the IPN gels could enhance mechanical properties, decrease swelling capacity and had better bile acid binding capacity. These results of gelatin-alginate gels provide references and novel prospects of IPN for the application in the field of food industry.

Novel composite gels of gelatin and soluble dietary fiber from black bean coats with interpenetrating polymer networks

The soluble dietary fiber (SDF) extracted from black bean coats was used to produce a novel composite gel with gelatin by forming an interpenetrating polymer network (IPN). The gel prepared by the cross-linking of transglutaminase (TG) and Ca2+ was called IPN gel, and the gel prepared only by TG or Ca2+ was named as G-semi-IPN and F-semi-IPN, respectively. The rheology and micro-morphology were observed to confirm the formation of semi-IPN and IPN. The thermodynamic, mechanical and hydration properties of gelatin-SDF composite gels with different cross-linking conditions were determined. It was found that the IPN gel had enhanced mechanical properties, better freeze-thaw stability and lower swelling capacity. Bile acid binding assays showed that both semi-IPNs and IPN had certain ability of binding bile acids. These studies on gelatin-SDF composite gels suggested a new strategy to increase the gelling ability of dietary fibers. In addition, it could improve the utilization of bean coats during the food processing.

Short silica fiber composites with simultaneous interpenetrating polymer networks constituted by siloxane and phenolic systems

Short silica fiber reinforced simultaneous interpenetrating polymer network (IPN) composites comprising of siloxane and resole phenolic units were synthesized through curing of polymethylsilsesquioxane (PMSQ) and phenolic polymer systems along with short silica fibre. IPNs were formed at various PMSQ/phenolic ratios, while weight percentage of silica short fiber was kept at 60% (by weight). The formation of IPN was confirmed by FTIR, TGA and DMA. The effect of IPN composition on the mechanical, thermal, thermo‐physical and dynamic mechanical properties was investigated. The variation in properties was well correlated with the morphological and phase distribution features of IPN and the interaction of matrix with silica fiber. It was found that phenolic addition improved the properties of PMSQ‐silica composite system substantially and the optimal obtained was with 25% phenolic for most of the properties (compressive and flexural strength, toughness and thermal conductivity) due to the complete miscibility of the resultant IPN and its superior interaction with silica fiber. Tensile strength and impact strength showed increasing trend with phenolic content. However, the char residue got decreased with increase in phenolic content. This study shows that the synergy of PMSQ and PF polymeric systems in the form of IPN is worthwhile to be explored further for various potential applications. POLYM. COMPOS., 39:4010–4019, 2018. © 2017 Society of Plastics Engineers

Interpenetrating Conducting Hydrogel Materials for Neural Interfacing Electrodes.

Conducting hydrogels (CHs) are an emerging technology in the field of medical electrodes and brain-machine interfaces. The greatest challenge to the fabrication of CH electrodes is the hybridization of dissimilar polymers (conductive polymer and hydrogel) to ensure the formation of interpenetrating polymer networks (IPN) required to achieve both soft and electroactive materials. A new hydrogel system is developed that enables tailored placement of covalently immobilized dopant groups within the hydrogel matrix. The role of immobilized dopant in the formation of CH is investigated through covalent linking of sulfonate doping groups to poly(vinyl alcohol) (PVA) macromers. These groups control the electrochemical growth of the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) and subsequent material properties. The effect of dopant density and interdopant spacing on the physical, electrochemical, and mechanical properties of the resultant CHs is examined. Cytocompatible PVA hydrogels with PEDOT penetration throughout the depth of the electrode are produced. Interdopant spacing is found to be the key factor in the formation of IPNs, with smaller interdopant spacing producing CH electrodes with greater charge storage capacity and lower impedance due to increased PEDOT growth throughout the network. This approach facilitates tailorable, high-performance CH electrodes for next generation, low impedance neuroprosthetic devices.

Poly(urethane urea)/polythiophene/carbon black composite

Novel segmented poly(urethane urea) (PUU) was prepared from polycaprolactone triol (soft segment), 4,4′-methylenebis(phenyl isocyanate) (hard segment), and hexamethylenediamine (chain extender). Graphitized carbon black (GCB) was used as filler. Conducting polythiophene (PTh) was infiltrated by chemical oxidative polymerization. The structure, morphology, mechanical properties, electrical conductivity, and voltage-triggered shape memory effect were demonstrated. The unique network morphology was observed by scanning electron microscope due to the generation of interpenetrating polymer networks (IPNs). The formation of PUU-PTh IPNs was due to the interpenetrating PTh and branched polycaprolactone triol structure. The PTh-modified PUU films reinforced with GCB showed 59% increase in tensile strength and 50% enhancement in Young’s modulus relative to the pristine matrix. The presence of PTh and increase in GCB content increased the conductivity of the composites. The conductivity of 10 wt% GCB-loaded PUU/PTh/GCB composite was raised to 0.089 Scm−1, which is higher than the neat PUU (0.91 × 10−2 Scm−1). The surface temperature of PUU/PTh/GCB 10 was also found to increase with time when a higher voltage was applied (40 V). Such a conductivity of composites was enough to show electroactive shape recovery up to 94% (40 V).

Influence of N-vynilcarbazole on the photopolymerization process and properties of epoxy-acrylate interpenetrating polymer networks

Abstract Photocured simultaneous epoxy-acrylate interpenetrating polymer networks (IPNs) were formed both under irradiation by UV-lamp and natural sunlight. The conversion degrees of functional groups were calculated by using data obtained from Fourier transform infrared (FTIR) spectroscopy. The influence of N-vynilcarbazole (NVC) as a photosensitizer on the kinetics of IPN photopolymerization was investigated. The conversion degrees of epoxy groups were revealed to increase significantly with the addition of NVC to the given systems. The phase morphology of IPNs was analyzed by optical and scanning electronic microscopy as well as by dynamic mechanical analysis (DMA). The data obtained using DMA method, which was used for analyzing the IPN samples with different component ratios, indicate the formation of both phase-separated and single-phase IPNs. The phase separation is occurred only in NVC-containing 50:50 IPN.

Soybean Oil‐Based Polyurethane–(Poly)acrylonitrile Interpenetrating Polymer Networks as Transparent Coating Materials

AbstractIn this study, soybean oil‐based polyurethane–(poly)acrylonitrile (PU–PAN) interpenetrating polymer networks (IPN) were synthesized by the reaction of soybean oil‐based polyol, isophorone diisocyanate, and acrylonitrile. The formation of IPN were confirmed by the FTIR and differential scanning calorimetry (DSC) studies. The mechanical properties such as tensile strength, Young's modulus, hardness, and abrasion resistance were found to be increased with the increase of PU content in the IPN. IPN showed higher thermal stability and lesser burning rate than PU. Surface morphology was observed by SEM and AFM studies. The IPN showed higher hydrophobic nature than PU, studied by contact angle measurement.

Hydrophilicity improvement of silicone rubber by interpenetrating polymer network formation in the proximal layer of polymer surface

A novel method composed of an interpenetrating polymer network (IPN) formation reaction in aqueous solution was developed to improve the hydrophilicity of silicone rubber (SR) substrate. This solution phase method is compatible, simple, and convenient for some sensitive biomedical applications of SR devices because of using water as reaction solvent instead of harmful chemicals. In this work, a sequential interpenetrating polymer network formation in the proximal layer of SR surface, using poly(2-hydroxyethyl methacrylate) (PHEMA), as the second network was conducted so that led to actually surface modification resulting in an improved hydrophilicity. The modified surfaces were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), contact angle measurement, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) to assess the wettability, chemical composition and morphology of the surface modified PDMS. The results indicated that the surface modification method offered a novel and facile approach to improve the hydrophilicity of SR without altering its bulk properties. This method could be suitable for biomedical applications because of using water as a monomer solvent and polymerization medium.

Printing continuously graded interpenetrating polymer networks of acrylate/epoxy by manipulating cationic network formation during stereolithography

Ultra-violet (UV) laser assisted stereolithography is used to print graded interpenetrating polymer networks (IPNs) by controlling network formation. Unlike the traditional process where structural change in IPNs is achieved by varying the feeding ratio of monomers or polymer precursors, in this demonstration property is changed by controlled termination of network formation. A photo-initiated process is used to construct IPNs by a combination of radical and cationic network formation in an acrylate/epoxy system. The extent of the cationic network formation is used to control the final properties of the system. Rapid-Scan Fourier Transformation Infrared Spectroscopy (RS-FTIR) is used to track the curing kinetics of the two networks and identify key parameters to control the final properties. Atomic force microscopy (AFM) and differential scanning calorimetry (DSC) confirm the formation of homogenous IPNs, whereas nano-indentation indicates that properties vary with the extent of cationic network formation. The curing characteristics are used to design and demonstrate printing of graded IPNs that show two orders of magnitude variation in mechanical properties in the millimeter scale.

Preparation and properties of polyurethane‐modified epoxy cured in different simulated gravity environments

ABSTRACTGreat attention has been paid to the composites with interpenetrating polymer networks (IPNs) because of their special performance. However, the influence of sedimentation and convection from different gravity environments on the formation of IPNs and the properties of IPNs blends has received little attention. To understand their influence, environments with different gravity accelerations of 0g, 1g, and 2g were simulated with a superconducting magnet, and tests, including differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), coefficient of thermal expansion (CTE), scanning electron microscopy, and three‐point bending, of the IPNs blends cured in different gravity environments were conducted and analyzed. Fourier transform infrared spectroscopy, DSC, and DMA proved the formation of IPNs during the reaction between the polyurethane prepolymer (PUP) and epoxy resin (E51). The curves of DSC also certified the differences in the curing degree between the different parts along the direction of gravity of a sample. With the increase of mass fraction of PUP, the change trends of the storage modulus presented a linear decrease when samples cured in microgravity environment, but presented a parabolic trend when samples were cured in terrestrial environment. The damping properties of samples cured in simulated microgravity environments are better than those cured in terrestrial environment. With the increase in the simulated acceleration of gravity, the diameter of dispersed phase in a sea‐island structure increased, but their number decreased and the bending stress and CTE of the IPN blends all decreased. These results show the formation of IPNs was affected by different gravity values, and the thermal and mechanical properties of the IPN composites were influenced by the changed IPN components. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42063.

Poly(vinyl alcohol) and poly(dimethylsiloxane)-based interpenetrating polymer networks via radical polymerisation

In this paper, interpenetrating polymer networks (IPNs) based on poly(vinyl alcohol) (PVA) and poly(dimethylsiloxane) with terminal vinyl groups (PDMS-vinyl) with both hydrophilic and hydrophobic features were prepared by radical reticulation. Specifically, an aqueous PVA solution was mixed with an alcoholic PDMS-vinyl solution in the presence of 2,2-dimethoxy-2-phenylacetophenone (DMPAP) and N’,N-methylenebisacrylamide (MBA) as initiating and reticulating agents, respectively, to obtain samples with the following PVA/PDMS-vinyl (w/w) compositions: 100/0, 75/25, 50/50, and 25/75. Confirmation of the IPN formation was done by a set of techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TG), differential scanning calorimetry (DSC), as well as theoretical calculations. The techniques used showed evidence of cross-linking reactions occurring in both PVA and PDMS-vinyl. Swelling experiments showed a proper balance of the resulting IPNs in swelling polar and apolar solvents, according to their composition and cross-linking. Tools of Theoretical Chemistry (Methods of Molecular Mechanics and Quantum Mechanics) were employed for the first time to investigate the cross-linking reaction between PVA and MBA and corroborate the experimental results. The PVA/PDMS IPNs showed a high capacity (up to 80 wt.%) to absorb water and may be characterised as hydrogels.

Modification of ultrafiltration membranes via interpenetrating polymer networks for removal of boron from aqueous solution

Interpenetrating polymer networks (IPNs) are polymeric structures formed when two distinct multi-functional polymers become entangled at the molecular level. Thus, an IPN permits the combination of chemical and physical properties of individual polymers in the same material. The objective of this work was to develop new ultrafiltration membranes with the capacity of boron retention via IPNs. Cellulose ultrafiltration membranes were used as substrate resin (or primary network) for in situ polymerization of a boron selective monomer based on N-methyl-d-glucamine. Structural properties, percent of secondary network, change of hydrophilicity, permeability and boron retention properties were studied. Results suggest that surface porosity is not affected by the formation of IPN. In addition, pore radius was decreased at 40.9% whereas the pore number was increased at 202.1% and values of boron retention were 20.5%, 17.8% and 14.8% for pHs 5.0, 7.0, and 9.0, respectively. It was concluded that new ultrafiltration membranes could be produced by in situ polymerization of vinyl monomer in order to improve their retention, surface, and permeability properties.

Polymer networks based in (4‐vinylbenzyl)‐N‐methyl‐D‐glucamine supported on microporous polypropylene layers with retention boron capacity

ABSTRACTNew cellulose porous layers, with capacity to transport and retain boron from aqueous solution, were developed via interpenetrating polymer network (IPNs). These polymer systems were made to assemble mimetic systems of plant root tissue for the study of available boron transport. For that cellulose porous layers supported on polypropylene matrix were used as primary network for the formation of IPN. A vinyl monomer, (4‐vinylbenzyl)‐N‐methyl‐d‐glucamine (VbNMDG), was synthesized at three concentration levels and cellulose ultrafiltration membranes were modified by in situ polymerization in the inside of the pores. Change of hydrophilicity, percent of secondary network, permeability and retention properties were studied. The formation of IPNs in the inside of the pores decreased the permeabilities of polymer layers. In addition, a decrease of hydrophilicity was seen. A linear increase of boron retention in function of VbNMDG concentrations was observed for the different boron concentrations and a negative effect on retention capability was evidenced for several charge and discharge cycles. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40653.

Tribological mechanism improving the wear resistance of polyurethane/epoxy interpenetrating polymer network via nanodiamond hybridization

ABSTRACTThe excellent synergistic effect of physical/mechanical properties of polyurethane/epoxy (PU/EP) interpenetrating polymer network (IPN) and the validity of nanofilling have one potential to improve the wear resistance of polymeric materials. With the aim of practical application, PU/EP IPN nanocomposites are prepared with nanodiamond (ND) as a reinforcing additive. Results showed the uniform thermal stability and the excellent compatibility between PU and EP in ND‐hybridized PU/EP IPN. Simultaneously, ND particles work as crosslinked points improving the physical/mechanical properties of ND‐hybridized PU/EP IPN, especially the wear resistance. The measurement of tribological property and the scanning electron microscope indicated that the wear resistance is able to be improved a lot by the formation of IPN and by the addition of ND. Consequently, the tribological mechanism of PU/EP IPN nanocomposites comes into being. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40244.

Synthesis and characterization of interpenetrating polymer networks from transesterified castor oil based polyurethane and polystyrene

A series of two component interpenetrating polymer networks (IPN) of modified castor oil based polyurethane (PU) and polystyrene (PS) were prepared by the sequential method. Castor oil was modified by triethanolamine by means of transesterification and designated as transesterified castor oil (TCO). The polyurethane network was prepared from transesterified castor oil (TCO) with the isophoronediisocyanates (IPDI) by using dibutyltindilaurate (DBTDL) as catalyst. Simultaneously styrene was added with benzoyl peroxide (BPO) as initiator and N,N′-Dimehtylaniline as coinitiator. Diallylphthalate was added as a crosslinking agent to form IPN and finally cast into films. To cast the film, the mixture (IPN) was poured in the glass cavity with pourable viscosity free from air bubbles. A series of two component interpenetrating polymer networks were prepared by varying % weight ratio of both polyurethane and polystyrene. These films were characterized by FT-IR, dynamic mechanical analysis (DMA), thermogravimetry analysis (TGA), morphology was measured by scanning electron microscopy (SEM). FT-IR have given the conformation of IPN formation. DMA results have shown much increase in the value of tanδ and a decrease in the value of Tg by increasing the anount of Styrene.

Preparation and characterization of IPN hydrogels composed of chitosan and gelatin cross-linked by genipin

The interpenetrating polymer networks (IPN) hydrogels based on chitosan and gelatin using genipin as the cross-linker were prepared and characterized. The IPN formation of the genipin-cross-linked chitosan/gelatin hydrogel was confirmed by means of the instrinsic viscosity measurement, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and the ninhydrin assays. The instrinsic viscosity measurement, FT-IR and SEM suggested that chitosan and gelatin were miscible in the molecular level. The miscibility leads to the formation of IPN after cross-linking. FT-IR also examined the cross-linking mechanism of genipin with primary amino groups. The degree of cross-linking increased with increase genipin concentration. Swelling results revealed that the IPN hydrogels are pH-sensitive, exhibiting reversibility and rather rapidly response in swelling to pH changes. It is expected this IPN hydrogel has potential as controlled drug delivery system or as alternative sorbents for biomedical and environmental use as pH altered.

Controlled Release of an Antihypertensive Drug through Interpenetrating Polymer Network Hydrogel Tablets of Tamarind Seed Polysaccharide and Sodium Alginate

The application of interpenetrating polymer network (IPN) hydrogel tablets of tamarind seed polysaccharide and sodium alginate for controlled release of a water-soluble antihypertensive drug, propranolol HCl (PPL), was investigated. The IPN tablets loaded with PPL or PPL–resin complex (resinate) were prepared by a wet granulation/covalent cross-linking method. Fourier Transform Infrared Spectroscopic confirmed the cross-linking reaction and IPN formation, while X-ray Diffraction and Scanning Electron Microscopy studies confirmed the amorphous dispersion of the drug within the IPN tablets. The plain drug PPL showed complete release within 1 h, while drug release from the resinate was prolonged for 2.5 h and the IPN matrices showed drug release up to 24 h. The drug release rate from the IPN matrices was affected by polymer concentration and cross-linking time; the higher the cross-linking time, the slower was the drug release. The drug release mechanism was found to be of a non-Fickian type.

Preparation and in vitro evaluation of xanthan gum facilitated superabsorbent polymeric microspheres

Interpenetrating polymer network (IPN) hydrogel microspheres of xanthan gum (XG) based superabsorbent polymer (SAP) and poly(vinyl alcohol) (PVA) were prepared by water-in-oil (w/o) emulsion crosslinking method for sustained release of ciprofloxacin hydrochloride (CIPRO). The microspheres were prepared with various ratios of hydrolyzed SAP to PVA and extent of crosslinking density. The prepared microspheres with loose and rigid surfaces were evidenced by scanning electron microscope (SEM). Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis confirmed the IPN formation. Differential scanning calorimetry (DSC) study was performed to understand the dispersion nature of drug after encapsulation. The in vitro drug release study was extensively evaluated depending on the process variables in both acidic and alkaline media. All the formulations exhibited satisfactory physicochemical and in vitro release characteristics. Release data indicated a non-Fickian trend of drug release from the formulations. Based on the results, this study suggest that CIPRO loaded IPN microspheres were suitable for sustained release application.

Novel Interpenetrating Polymer Networks Based on Natural Rubber/Poly(vinyl alcohol)

Fully interpenetrating polymer networks (IPN) based on natural rubber (NR) and poly(vinyl alcohol) (PVA) were prepared by using glutaraldehyde as the common cross-linking agent. The mechanical performance of this system has been studied in detail. Stress-stain behavior, tensile strength, elongation at break and young's modulus was determined. Effects of weight fraction on the physical properties of NR/PVA IPN's were also studied along with the thermal degradation behavior using thermogravimetric analysis. A remarkable improvement was observed in the mechanical strength and the thermal stability of the blend by the formation of IPN. The activation energy of degradation was analyzed using the Horowitz-Metzger equation. The solvent resistance properties of these samples were investigated by the equilibrium swelling method using benzene as a solvent. The impact of weight fraction of PVA on the solvent transport of the system was also analyzed. A reduction in swelling was exhibited with the addition of PVA to natural rubber by the formation of IPN. The water absorbability of the blend decreases by the addition of glutaraldehyde.

Interpenetrating polymer network (IPN) hydrogel microspheres for oral controlled release application

Interpenetrating polymer network (IPN) hydrogel microspheres of sodium carboxymethyl cellulose (NaCMC) and poly(vinyl alcohol) (PVA) were prepared by water-in-oil (w/o) emulsion crosslinking method for oral controlled release delivery of a non-steroidal anti-inflammatory drug, diclofenac sodium (DS). The microspheres were prepared with various ratios of NaCMC to PVA, % drug loading and extent of crosslinking density at a fixed polymer weight. The prepared microspheres with loose and rigid surfaces were evidenced by scanning electron microscope (SEM). Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis confirmed the IPN formation. Differential scanning calorimetry (DSC) study was performed to understand the dispersion nature of drug after encapsulation. The in vitro drug release study was extensively evaluated depending on the process variables in both acid and alkaline media. All the formulations exhibited satisfactory physicochemical and in vitro release characteristics. Release data indicated a non-Fickian trend of drug release from the formulations. Based on the results of this study suggest that DS loaded IPN microspheres were suitable for oral controlled release application.