Interpenetrating Polymer Networks, High Performance
Authors: Selvaraj M. 
Published: July 2012

High performance interpenetrating polymer network (IPN) technology covers different kinds of important IPNs used in industrial coatings, aerospace, and adhesive application. The importance of sequential IPN, simultaneous IPN, thermoplastic IPN, latex IPN (LIPN), and gradient IPN is reviewed with their synthesis, properties, and phase morphologies. High performance IPNs prepared by sequential method have improved the corrosion resistance as well as high temperature‐withstanding ability. The synergistic effect of IPN is explained. The mechanical performances of the compositions are improved by simultaneous IPN synthesis method. It is explained through the Takayanagis model equation. Thermoplastic IPN is explained through the synthesis of polypropylene (PP)/ethylene‐propylene‐diene monomer (EPEM) IPN, which is used as a coating for the plastic components of automobile industries. Ecofriendly high performance LIPN is also explained through the morphological changes during the formation of IPN.

Thermoresistant high performance IPN has been explained with the synthesis of epoxy silicone titanate IPN. Their chemistries, structural illustrations, and infrared (IR) spectroscopy are also described. Thermogravimetric analysis exhibits considerable improvements in heat resistance property when 20% titanate w/w is used to cure the epoxy silicone polymer. The surface morphology study confirms that only 10% siloxane content enhances the thermal stability of the IPN. Further, the incorporation of heat‐resistant pigments such as hexagonal structured silicon carbide and flaky structured graphite in this IPN still enhances the thermal stability to protect the steel structure for long duration.

Corrosion‐resistant high performance IPN synthesized from epoxy acrylic polyurethane by graft as well as full IPNs are described in a detailed manner. Moisture vapor transmission rates of these IPNs are measured, and it is found that the IPNs have very low rate of moisture transmission power than that of the neat polymers. This is explained by the fact that the interlocking of the polymer segments inhibits the water permeation process. The electrochemical impedance studies (EIS) indicate that the resistance exerted by most of the IPNs is in the range of 108 Ω cm2after 80 days of exposure in 3% w/v sodium chloride solution. This enhanced resistance of IPNs proves that the IPNs have high performance to protect the metal surfaces from the corrosive environment rather than from the corresponding neat polymer systems. Further, IPN is used as a weather‐resistant coating. It is also established that unlike epoxies, this IPN can be used as a top coat system because it is not affected by ultraviolet (UV) radiations.

Dual curing acrylic hyperbranched polyester IPN systems are mainly used for protecting the plastic parts of automobiles. Dynamic mechanical analysis to determine the properties of these IPNs is explained. Various mechanical properties, such as hardness, flexibility, storage modulus, and cross‐linking density of the IPNs are obtained from the dynamic mechanical analysis (DMA), and spectral analysis is explained through the experimental result. The homogeneity of IPN identified from the width of the loss tangent peaks is also explained in this review.

High performance LIPN formulation methods are explained. These IPN emulsions have better mechanical, chemical, and accelerated weathering properties than the respective polymer and polymer blends. The ecofriendly LIPN can be utilized as a high performance industrial coating. Conducting polymer IPN has the controlled drug releasing property, so it is used in the medical field. These IPNs are also used in smart coating formulations. Further, conducting polymer IPN has better corrosion and thermoresistance than the neat polymers.