Morphology of Composite Films Based on Poly(N-vinylcaprolactam) with Titanium Dioxide Nanoparticles
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Morphology of Composite Films Based on Poly(N-vinylcaprolactam) with Titanium Dioxide Nanoparticles O. I. Timaevaa*, A. S. Orekhovb,c, G. M. Kuz’michevaa, V. V. Klechkovskayac, and I. P. Chihachevaa a MIREA
- Russian Technological University, Moscow, 119571 Russia Research Center “Kurchatov Institute,” Moscow, 123182 Russia c Shubnikov Institute of Crystallography, Federal Research Centre “Crystallography and Photonics,” Russian Academy of Sciences, Moscow, 119333 Russia *e-mail: [email protected] b National
Received March 17, 2017; revised May 9, 2018; accepted June 7, 2018
Abstract—PVCL25 and PVCL40 films have been synthesized by poly(N-vinylcaprolactam) (PVCL) aqueous solution flow coating and complete desiccation below (∼32–34°С) and above (40°С) the coil–globule phase transition temperature (ТPT) and (Hombifine N/PVCL)25 and (Hombifine N/PVCL)40 nanocomposite films added with Hombifine N (nanoanatase) have been obtained. The films are studied by X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray microanalysis. The differences between the compositions and structural characteristics of the PVCL25 and PVCL40 films and (Hombifine N/PVCL)25 and (Hombifine N/PVCL)40 nanocomposites are found. It is established that the (Hombifine N/PVCL)40 nanocomposite film desiccated at Т > ТPT contains PVCL globules, inside which nanoanatase associates with ОН groups are located on the nanoparticle surface. These assocoiates are bound with water molecules in PVCL by hydrogen bonds, which makes the (Hombifine N/PVCL)40 nanocomposite a unique material with physicochemical properties differing from those of (Hombifine N/PVCL)25 nanocomposite. DOI: 10.1134/S1063774519010280
in temperature and undergo a coil–globule transition, which is widely used in biotechnology and medicine [2, 3]. A representative of temperature-responsive polymers is poly(N-vinylcaprolactam) (PVCL), which consists of a hydrophobic polymer chain (–CH2–CH2–) and a caprolactam ring with the hydrophilic amide group (N–C=O) and undergoes a phase transition at a temperature (ТPT) of 32–34°С. In an aqueous solution, each monomeric unit can bind two water molecules into a highly hydrated system below ТPT. An increase in the polymer solution temperature leads to break of hydrogen bonds, dehydration, and intra- and intermolecular hydrophobic interactions, which results in the transformation of polymer coils into insoluble globules (precipitate) in water. In this case, the spatial arrangement of macrochains also changes: hydrophobic chain segments prevail at the globule center, whereas hydrophilic ones dominate on its periphery [4, 5].
INTRODUCTION A combination of components of different chemical origin (e.g., a polymer and an inorganic compound) during synthesis of composites may lead to the formation of a material with characteristics superior or different from those of the constituents. The effect of an inorganic compound on the properties of composites depends on its composition, structure, concentration
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