Castor and Linseed oil Polyurethane/TEOS Hybrids as Protective Coatings

In the present study, preparation, characterization and coating properties of plant oils based organic-inorganic hybrid materials [OIHM] are described. Polyols from Castor oil [CO], Linseed oil [LO] and tetraethoxyorthosilane [TEOS] serve as organic and inorganic constituents, respectively. OIHM are prepared by “hydrolysis-condensation” reactions. The hydroxyl groups of polyols condensed with TEOS, forming silica anchored polyol based OIHM which on addition reaction with isocyanate formed polyurethane hybrids [COHM-PU and LPOHM-PU]. In FTIR spectra of OIHM, absorption bands at 800 cm−1(Sisingle bondOsingle bondSi sym str) and 1090.0 cm−1 (Si-O-Si assym str) confirmed the formation of nano silica, that occurred as unagglomerated and spherical particles as observed in TEM micrographs of OIHM. Thermogravimetric analysis showed the onset of degradation at 220 °C–225 °C. OIHM showed moderate to good antibacterial behavior against E.coli and S.aureus. OIHM coatings showed good corrosion rate and inhibition efficiency in 3.5 wt% NaOH, 3.5 wt% HCl and performed well in salt fog environment. The corrosion rate and IE% values for COHM-PU were found to be 1.534 × 10−2 mm/yr and 94.208%, and 9.923 × 10−3 mm/yr and 95.062% for LPOHM-PU, in 3.5 wt% NaOH for 0.5 mol loading of TEOS. In 3.5 wt% HCl, corrosion rate was 9.78 × 10−3 mm/year for COHM-PU with IE% value as 91.90% and 7.98 × 10−3 mm/year for LPOHM-PU with IE% value as 93.44%. OIHM were developed via a synergistic approach wherein plant polyols provide matrix for the production of SiO2; the latter act as reinforcements improving the performance properties in hybrid polyurethane. OIHM may serve as platform chemicals for numerous industrial products such as paints and coatings.

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Volume 108, July 2017, Pages 1–14

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