Semi-interpenetrating polymer networks stabilization

Kumar, H., Anilkumar, A., and Siddaramaiah. 2006. Physico-mechanical, thermal and morphological behaviour of PU/PMMA semi interpenetrating polymer networks. Polymer Degradation and Stability 91 1097-1104. 

Semi-interpenetrating polymer network membranes based on sulfonated polyimide-siloxane and epoxy polymers have been prepared [61]. The membranes show desirable mechanical properties and thermal stabilities, with proton conductivities superior to those of Nation 117 at 80 °C. 

Rosu, D., Rosu, L., Varganici, C.-D. The thermal stability of some semi-interpenetrated polymer networks based on epoxy resin and aromatic polyurethane. J. Anal. Appl. Pyrol. 100, 103-110 (2013)... 

J. Seo, W. Jang, S. Lee, H. Han, The stability of semi-interpenetrating polymer networks based on sulfonated polyimide and poly (ethylene glycol) diacrylate for fuel cell applications, Polym. Degrad. Stab. 93 (1) (2008) 298-304. 

Another class of cross-linked networks incorporating NLO chromophores based on a semi-interpenetrating polymer network (semi-IPN) [105] and fully interpenetrating polymer networks (full-IPN) [106-108] has been investigated. These systems were developed to enhance temporal stability by realizing the ability of an IPN structure to improve the viscoelastic properties of polymers. The semi-IPN system was prepared by combining a high 7g polyimide and a sol gel network [105]. The poled semi-IPN sample has a of 28 pm/V at 1.064 /x,m. After over 168 h at 120°C, a retention of 13% of the d value was observed. 

Perfluorinated sulfonic acid polymers, such as Nafion membranes, were the most commonly used materials in practical systems for their high proton conductivity and extremely high oxidative stability. However, due to the poor dimensional stability, low mechanical properties of Nafion at high humidity and high temperature, and high cost, an essential need for cost-effective and reinforced substitutes with improved performance arises [193-195]. Nafion blended with the second component could not only reduce the cost, but also improve the mechanical properties and the dimensional stability. Recently, the reinforced composite membranes based on semi-interpenetrating polymer network (semi-IPN) structures of Nafion , polyimidazole (PI) [196-198], polybenzimidazole (PBI) [199], and poly(vinyIidene fluoride) (PVDF) [200] were reported. As shown in Fig. 2.35, the composite membranes with... 

Semi interpenetrating polymer networks pPNs) of carboxymethyl cellulose (CMC) and polyacrylic acid were prepared by Bajpai et. al. [130] and its potential for controlled release of ciprofloxacin were assessed. The IPNs were characterized by IR spectral analysis and ESEM analysis. The entrapped drug was examined for its antibacterial activity and chemical stability. The effects of experimental parameters such as vaiying chemical composition of the IPNs, % loading of Cfe (ciprofloxacin) hydrochloride, pH, and temperature of release medium and presence of salts ions in outer solution were examined on the release profile of the drug. 

Interpenetrating polymer networks (IPNs) have been the subject of extensive study since their advent in the 1960s. The IPN is a combination of two polymers in network form, at least one of which is synthesized and/or cross-linked in the immediale presence of the other. In this section, we will refer to the research in recent years on the IPN or semi-IPN based on BMI. A special class that is part of the IPN network is made up of the bismaleimide-triazine (BT) resins based on BMI and dicyanate ester (CE), which has many attractive properties such as very good thermal stability, moisture resistance, low dielectric constant, and low dielectric loss. The cure mechanism of their blends was highly controversial and sometimes conflicting, and all research done on this subject until the year 2006 led to the conclusion that CE... 

Semi-IPNs were prepared by the sol-gel technique through in situ polymerization of BMI in thermoplastic polyetherimide (PEI) as well as in polysulfone (PSF) (Kurdi and Kumar 2006). Structure and properties of semi-IPN membranes could be varied by controlling the thermoset BMI microdomain size interpenetrating within a thermoplastic polymer network. The size of this microdomain depended on the polymerization time of BMI and on the degree of thermoset/thermoplastic phase separation. These semi-IPN membranes showed an improved Tg but a decrease in their thermal stability and could be used for Oj-emiched-air applications where high selectivity is not required. At ambient temperature, it was possible to increase the permeance of semi-IPN membranes. 

Second-order NLO materials with superb stability based on semi-IPN and IPN systons have been demonstrated. The high rigidity of polymer backbones, increased crosslinking density, and interpenetrating network architecture are important factors for the material design and development. The relaxation behavior of the IPN system was found to be fundamentally different fiem that of a guesl/host system. 

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