Synthesis and characterization of nanosilica/waterborne polyurethane end‐capped by alkoxysilane via a sol‐gel process

Abstract

A novel method was used to synthesis nanosilica/waterborne polyurethane (WPU) hybrids by in situ hydrolysis and condensation of tetraethyl orthosilicate (TEOS) and/or 3-aminopropyltriethoxylsilane bonding at the end of the WPU molecular chain. The hybrid was characterized by scanning electron microscopy, energy dispersive spectroscopy (EDS), transmission electron microscopy, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The results showed that the nanosilica/WPU hybrids with well-dispersed nanosilica particles were synthesized, in which the particles had typical diameters of about 50 nm. In addition, XPS and FTIR analyses demonstrated that chemical interaction occurred between WPU and silica. The effects of TEOS on surface wettability, water resistance, mechanical strength, and thermal properties of the hybrid were also evaluated by contact angle measurements, water absorption tests, mechanical tests, and differential scanning calorimetry, respectively. An increase in advancing contact angles, water resistance, and tensile strength, as well as decrease in elongation at break and glass transition temperature, were obtained with the addition of TEOS. Water absorption decreased from 17.3 to 5.5%. The tensile strength increased to a maximum of 29.7 MPa, an increase of about 34%. Elongations at break of the hybrids decreased 191%. These results were attributed to the effects of the nanosilica and the chemical interaction between WPU and silica.

Preparation and properties of Waterborne polyurethane/nanosilica composites: A diol as extender with triethoxysilane group

“…The reason may be that WPU contained SiOCH 2 CH 3 or SiOH group, but these groups transferred to SiOSi after incorporating nanosilica into WPU. The peak at 460 cm −1 corresponding to SiOSi group also confirmed this suggestion . PU prepolymer showed weak absorption peak at this situation, but this peak became stronger progressively after emulsion and incorporating nanosilica.…”

“…Interfacial interaction between WPU and nanosilica is the decisive factor for the properties of WPU/nanosilica composites. Because the interactions between WPU and nanosilica are often physical or weak phase interaction such as hydrogen bonding and Van der Waals bonding, incorporating nanosilica into WPU always leads to unstable emulsion, nanosilica aggregation and poor mechanical properties . In recent years, sol–gel process and in situ polymerization have been developed to prepare WPU/nanosilica composites to solve these problems .…”

Fabrication and properties of novel superparamagnetic, well – Dispersed waterborne Polyurethane/Ni–Zn ferrite nanocomposites

“…The second weigh loss stage occurred at 398-510 °C, which may be attributed to the decomposition of the soft segment of the WPU matrix. [26,27] M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 11 Furthermore, the degradation temperature for nanocomposites in the second stage shifts toward higher temperatures than those of the pure one; greater functionalized NZFO contents lead to higher temperature. The weight loss decreased as the NZFO-IPTS content increased.…”

Preparation of Two-Component Polyurethane Coatings from Bleached Liquefied Wood

“…The elasticity of the films was not changed. Improvement of the properties (strength and water resistance) of PU films modified with various silanes were reported by many authors (Xia and Larock 2011;Zhai et al 2013;Allauddin et al 2013, Fu et al 2014, but application of n-octyltriethoxysilane 4000 3200 2400 1800 1400 1000 650…”

“…Excluding numerous reports on silane treated (nano) particles in PU coatings, it is known that the resistance of coatings to water can be improved also by treatment of resins or formulations with silanes (Materne et al 2012). For example, Zhai et al (2013) observed that PU endcapped by alkoxysilane (tetraethyl orthosilicate) via a sol-gel process increased the water contact angle and water resistance of coating films. Similarly, approach with silane endcappers was applied in the case of polyurethane based adhesives, resulting in their improved properties (Nomura et al 2007).…”