Artigo de peri??dico
Qualitative and semiquantitative determination of the atomic and molecular tungsten distributions in hybrid hydroxyurethanes???poly(dimethylsiloxane) films containing phosphotungstates ([PW12O40]3???)
Registro en:
0003-7028
12
74
10.1177/0003702820945018
54.28
70.00
Autor
YSNAGA, ORLANDO E.
AGUIAR, KELEN M.F.R. de
ZAMBONI, CIBELE B.
POLITO, WAGNER L.
RODRIGUES-FILHO, UBIRAJARA P.
Resumen
In this study, hybrid poly(dimethylsiloxane)-derived hydroxyurethanes films (PDMSUr-PWA) containing phosphotungstic
acid (H3PW12O40/PWA) were characterized using field emission gun scanning electron microscopy (FEG-SEM), in attenuated
total reflectance Fourier transform mid-infrared mode (ATR FT-MIR), and analyzed using synchrotron radiation
micro-X-ray fluorescence (SR-mXRF), synchrotron radiation grazing incidence X-ray fluorescence (SR-GIXRF), laserinduced
breakdown spectroscopy (LIBS), and instrumental neutron activation analysis (NAA) in order to correlate the
distribution patterns of tungsten and properties of PDMSUr-PWA films. PDMS constitute elastomers with good mechanical,
thermal, and chemical (hydrophobicity/non-hygroscopy) resistance. Currently, products based on urethanes (e.g.,
polyurethanes) are widely used in many applications as plastics, fiber-reinforced polymers, high-performance adhesives,
corrosion-resistant coatings, photochromic films, among others. The possibility to combine inorganic and organic components
can produce a hybrid material with unique properties. PWA has an important role as agent against the corrosion
of steel surfaces in different media, besides exhibiting amazing catalytic and photochromic properties in these films. PWA
kept its structure inside of these hybrid films through interactions between the organic matrix of PDMSUr and silanol from
the inorganic part (organically modified silica), as was shown using ATR FT-MIR spectra. The FEG-SEM/SR-mXRF/wideangle
X-ray scattering (WAXS)/X-ray diffraction (XRD)/energy dispersive X-ray results proved the presence of PWA in
the composition of domains of PDMSUr-PWA films. At PWA concentrations higher than 50 wt%/wt, tungsten segregation
across the thickness is predominant, while that at PWA concentrations lower than 35 wt%/wt, tungsten segregation at
surface is predominant. Inhomogeneities in the tungsten distribution patterns (at micrometric and millimetric level) may
play an important role in the mechanical properties of these films (elastic modulus and hardness). Funda????o de Amparo ?? Pesquisa do Estado de S??o Paulo (FAPESP) Conselho Nacional de Desenvolvimento Cient??fico e Tecnol??gico (CNPq) FAPESP: 11/08120-0; 11/06019-0; 13/05279-3 CNPq: 141880/2011-2; 160515/2011-4