Irradiation effects in poly(ethylene oxide)/silica nanocomposite films and gels

Abstract

Poly(ethylene oxide)/silica (PEO/SiO2) nanocomposite films were modified, and nanocomposite gels were prepared by γ‐irradiation up to 100 kGy. Thermal analysis, optical microscopy, X‐ray diffraction, and Fourier transform infrared spectroscopy revealed that the outcome mostly depended on the state of the PEO matrix on irradiation and that the state of the sample had a bearing on the effect of nanosilica addition. In unirradiated films, nanosilica induced heterogenous nucleation and increased crystallization temperatures proportional to its content. On irradiation of nanocomposite films, degradation prevailed, resulting in an increased crystallinity of samples irradiated to 50 kGy and a significant deterioration of mechanical properties at higher doses. In films irradiated in air, nanosilica did not provide radiation resistance. It enhanced oxidative degradation by increasing the content of a more radiation sensitive amorphous phase and probably facilitated the crystallization of broken chains resulting in an additional crystallinity increase. In the same dose range, the irradiation of PEO/nano‐SiO2 aqueous solutions produced cross‐linked nanocomposite gels of much lower crystallinity and phase transformation temperatures and better mechanical properties. Interactions and radiation‐induced effects in nanosilica likely contributed to a further crystallinity reduction in nanocomposite gels. Pronounced changes on the addition of 20 wt% of nano‐SiO2 to both nanocomposite films and gels indicate a possible synergism of γ‐irradiation and nanoparticle addition. POLYM. ENG. SCI., 53:2318–2327, 2013. © 2013 Society of Plastics Engineers

Rheological, Microstructural and Thermal Properties of Magnetic Poly(Ethylene Oxide)/Iron Oxide Nanocomposite Hydrogels Synthesized Using a One-Step Gamma-Irradiation Method

“…Crosslinks also impose restrictions on molecular motions of PEO chains and at high doses the high density of PEO crosslinks and a small segment of PEO chains between two crosslink junctions seriously impede crystallizability, resulting in a significant lowering of T c . Such a decrease of T m and enthalpies of melting with the dose for PEO gels was also reported by other authors [ 12 , 30 , 47 ].…”

“…γ-irradiation (radiolytic method) has the advantage of a pure and homogeneous initiation of the polymer crosslinking reaction and reduction of metal cations, as well as the sterility of the final product. Typically, nanocomposite gels are synthesized by two-step methods: (i) γ-irradiation induced crosslinking of the polymer in solution in the presence of pre-prepared nanoparticles (NPs) [ 12 , 13 ] or (ii) in situ γ-irradiation synthesis of nanoparticles within the already prepared polymer gel [ 14 , 15 , 16 , 17 ]. Of particular interest is the one-step γ-irradiation synthesis of nanocomposite gels.…”

“…For instance, it is used as wound dressings and hydrogels for active substance release. Upon γ-irradiation of PEO aqueous solutions, PEO easily crosslinks and forms macroscopic “wall-to-wall” hydrogels [ 12 , 30 , 31 , 32 , 33 ]. In this work, we optimized the experimental conditions and synthesized magnetic PEO/iron oxide nanocomposite hydrogels in one step starting from an alkaline aqueous suspension of PEO and Fe 3+ precursor.…”

Ionic Liquid-Based Polymer Electrolytes via Surfactant-Assisted Polymerization at the Plasma–Liquid Interface

“…[38][39][40] It has been reported that the formation of C=C and C=O bonds is a result of either disproportionation of the ethylene oxide unit macro-radicals in the region with a lower concentration of O 2 or decomposition of these radicals (SI, Figure S2). 41 The presence of functional group peaks after the deconvolution is consistent with the FTIR results. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 In the initiation stage, the radical generation is mainly attributed to hydrogen abstraction, chain scission of ethylene oxide groups, and fluorine dissociation of fluoroborate groups under a high energy dose of plasma irradiation.…”

“…47 Thus, we could project that the ionic conductivity would be decreased with increasing Triton X100 molar content. 41 This implies that the formation of C=C bonds causes a reduction of the concentration of active radicals that bind to create crosslinking. As a consequence, the crosslinking density is somewhat lower with respect to an increase in intensity of C=C bonds.…”