Properties Of Interpenetrating Polymer Networks Research Articles

Characterization Methods to Determine Interpenetrating Polymer Network (IPN) in Hydrogels.

Significant developments have been achieved with the invention of hydrogels. They are effective in many fields such as wastewater treatment, food, agriculture, pharmaceutical applications, and drug delivery. Although hydrogels have been used successfully in these areas, there is a need to make them better for future applications. Interpenetrating polymer networks (IPNs) can be created to make hydrogels more adjustable and suitable for a specific purpose. IPN formation is an innovative approach for polymeric systems. It brings two or more polymer networks together with entanglements. The properties of IPNs are controlled by its chemistry, crosslinking density, and morphology. Therefore, it is necessary to understand characterization methods in order to detect the formation of IPN structure and to develop the properties of hydrogels. In recent studies, IPN structure in hydrogels has been determined via chemical, physical, and mechanical methods such as Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), X-ray diffraction (XRD), and rheology methods. In this paper, these characterization methods will be explained, recent studies will be scrutinized, and the effectiveness of these methods to confirm IPN formation will be evaluated.

Synthesis and characterization of interpenetrating polymer networks (IPNs) based on UV curable resin and blocked isocyanate/polyols

Interpenetrating polymer networks (IPNs) are a non-bonded combination of two or more cross-linked polymers and have superior mechanical properties. Herein we synthesized a series of IPNs by a sequential UV-thermal dual-curing method, which is consisted of UV curable resin network and polyurethanes (PU) network. Blocked isocyanate (BI), polyols, and UV curable resin solutions were mixing completely, the resulting mixture was exposed to UV light to obtain a single network. Then the double network was formed via thermally triggered reaction of deblocking-isocyanate and polyols. The effect of polyol hydroxyl number (from two to six) on properties of IPNs was systematically studied. The results exhibit that pentaerythritol as polyol can be dual-cured by UV and heating to give the highest tensile strength (17.5 MPa), of a 21% increase compared to unheated sample. Furthermore, a series of semi-interpenetrating networks (semi-IPNs) were obtained by using polytetramethylene ether glycol (PTMEG) instead of the polyols. The results showed that introducing interpenetrating or semi-interpenetrating networks exhibit improved mechanical properties of the UV curable resin. Besides, the deblocking temperature of BI is just appropriate for the 3D-printing temperature.

Preparation and Characterization of Poly(2-Hydroxyethyl Methacrylate) and Castor Oil Based Uralkyds Interpenetrating Polymer Networks

Interpenetrating polymer networks (IPNs) of poly[2-hydroxyethylmethacrylate] and uralkyd prepolymer were synthesized using benzoyl peroxide as initiator, polyethylene glycol as chain extender, and N,N-methylene bis acrylamide as crosslinker by sequential polymerization method. The concentration of uralkyd (UA) prepolymer and poly[2-hydroxyethylmethacrylate] (PHEMA) were varied and their effects on chemical, mechanical, thermal, and morphological properties of IPNs were investigated. The IPNs glass-transition temperatures increase with increasing PHEMA concentrations. Tensile strength, and shore A hardness increases with increasing concentration of PHEMA while sacrificing percent elongation. Almost all IPNs have shown similar chemical resistance irrespective of composition. Thermo gravimetric analysis (TGA) indicated that increase in PHEMA concentration increases thermal stability of IPNs. Morphological analysis reveals that IPNs reveals heterogeneous and compact morphologies with distinct microphase separation.

Pseudo Interpenetrating Polymer Networks (IPNs) Based on Epoxy Resin (TGDDM) and POLY(STYRENE): Morphology and Properties

Pseudo-interpenetrating polymer networks (IPNs) of an epoxy resin and poly(styrene), PS, were prepared by the simultaneous mode of synthesis. The structure of the epoxy resin, N', N'- tetraglycidyl - 4,4'- diamine diphenyl methane, TGDDM, (Araldite MY- 720), was confirmed by infrared spectroscopy, elemental analysis and nuclear magnetic resonance (NMR) spectroscopy. The polymer networks produced from this epoxy resin cured with ethylenediamine (EDA) or triethylenetetramine (TETA) and IPNs were investigated by means of their morphology, thermal and mechanical properties. Differential scanning calorimetry (DSC) showed that the maximum conversion (a) was reached after 4 hours of cure at 40°C, using either EDA or TETA. The reactivity of TGDDM using TETA was approximately the same as that using EDA. The stability of the materials at PS/TGDDM compositions of 2/98, 6/94 and 8/92 (styrene wt.% / epoxy resin wt.%). was approximately the same as that of the epoxy resin cured by EDA and TETA. The mechanical properties of IPNs at low compositions of PS are similar to those of the epoxy resin cured with EDA and TETA. The curing agent, reaction rate, and composition of PS strongly influence the morphology of the materials.

STUDY ON THE MORPHOLOGY AND PROPERTIES OF INTERPENETRATING POLYMER NETWORKS OF POLY(ANTIMONY ACRYLATE) AND POLY(BISMUTH ACRYLATE)

A series of semi-IPN based on poly(antimony acrylate) and poly(bismuth acrylate), using benzoyl peroxide in DMF and divinylbenzene as crosslinking agents, has been synthesized. The values of coefficient of interaction (K AB) between the two polymers in solvents such as DMSO, DMF, and dioxane reflect contraction of the polymer coils in the order DMSO > DMF > dioxane. The scanning electron microscopy (SEM) reveals a dual-phase morphology of both metal acrylates. Properties like percentage swelling, average molecular weight between crosslinks (M c), and Young's modulus increase with concentration of poly(antimony acrylate) and poly(benzoyl peroxide). However, they decrease with concentration of bismuth acrylate and divinyl benzene. The differential scanning calorimeter (DSC) curve shows two glass transition temperatures for IPN at 60 and 72°C. The value of activation energy, calculated from thermogravimetric analysis, is 20 KJ/mol.

A Review of Kinetic Studies on the Formation of Interpenetrating Polymer Networks

Interpenetrating polymer networks (IPNs) are unique alloys of crosslinked polymers. This article reviews the studies on kinetic effects involved in IPN formation. Several investigators have studied the effect of kinetics of curing reactions on the morphology and properties of IPNs. It was found, in general, that the faster the rates of the respective chain extension and crosslinking reactions are and the closer they are to simultaneity, the more homogeneous are the IPNs. Other investigations revealed that the individual components sometimes can polymerize more rapidly in the IPN than alone, due to a “solvent effect” of the IPN. Effects of changing reaction variables, such as NCO/OH ratio, composition activators and temperature were used to study reaction kinetics as well as phase morphology by the Fourier transform infrared technique. Thermochemical techniques have been utilized to study the kinetics of IPN formation which influence phase separation. Small-angle X-ray scattering and small-angle neutron scattering techniques were used to estimate the extent of microheterogeneity of the phase domains in a study of the kinetics of phase separation in the IPNs.

Polymers from Renewable Resources. IV. Castor-Oil-Based Interpenetrating Polymer Networks Derived from Isophorone Diisocyanate Poly(Acrylamide) and Poly(Methacrylamide)

Abstract A number of polyurethanes were synthesized by reacting castor oil with isophorone diisocyanate while varying the NCO/OH ratio. All these polyurethanes were reacted with such acrylic monomers as acrylamide and methacrylamide by using ethylene glycol dimethacrylate as a crosslinker and benzoyl peroxide as the initiator. The physicochemical properties of interpenetrating polymer networks (IPNs) are reported. The durability, solvent absorption, outdoor weathering, and aging properties of IPNs have been studied. Thermogravimetric analysis was used to study the thermal behavior of IPNs and the evaluation of kinetic parameters. A number of equations, such as those of Freeman-Anderson, Broido, Piloyan-Novikova, Horowitz-Mitzger, and Coats-Redfern, have been used to determine the kinetic parameters. The degradation mechanism is discussed.

Interpenetrating polymer network of polyurethane and unsaturated polyester: Mechanical properties

Interpenetrating polymer networks (IPNs) of polyurethane (PU) and unsaturated polyester (UP) were prepared in this study. The mechanical properties of the IPNs were determined to relate to their structure. In order to improve the mechanical properties of the resultant IPNs, it was found that the -OH group present in the UP should be employed to react with some isocyanate-terminated PU prepolymer. Thus, the PU and UP were, in fact, interpenetrated with each other and chemically bonded through a grafting reaction to form the graft-IPN. The tensile strength of the IPNs was increased to a maximum value and then decreased as the PU content increased. The Izod impact strength and fracture energy of the IPNs increased more or less with an increase of the PU content, depending on the types, chain length of polyols used in the PU and the degree of the grafting reaction between PU and UP.