The Effect of Different Coupling Agents on Nano-ZnO Materials Obtained via the Sol–Gel Process

Violeta Purcar,Hermine Stroescu,Ioana Gîfu,Ludmila Cinteză,Elvira Alexandrescu,Sabina Niţu,Cristian-Andi Nicolae,Raluca Şomoghi,Simona Căprărescu,Augusta Gabor,Raluca Ianchiş

doi:10.3390/nano7120439

Abstract

Hybrid nanomaterials based on zinc oxide were synthesized via the sol–gel method, using different silane coupling agents: (3-glycidyloxypropyl)trimethoxysilane (GPTMS), phenyltriethoxysilane (PhTES), octyltriethoxysilane (OTES), and octadecyltriethoxysilane (ODTES). Morphological properties and the silane precursor type effect on the particle size were investigated using dynamic light scattering (DLS), environmental scanning electron microscopy (ESEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and X-ray diffraction (XRD). The bonding characteristics of modified ZnO materials were investigated using Fourier transform infrared spectroscopy (FTIR). The final solutions were deposited on metallic substrate (aluminum) in order to realize coatings with various wettability and roughness. The morphological studies, obtained by ESEM and TEM analysis, showed that the sizes of the ZnO nanoparticles are changed as function of silane precursor used in synthesis. The thermal stability of modified ZnO materials showed that the degradation of the alkyl groups takes place in the 300–500 °C range. Water wettability study revealed a contact angle of 142 ± 5° for the surface covered with ZnO material modified with ODTES and showed that the water contact angle increases as the alkyl chain from the silica precursor increases. These modified ZnO materials, therefore, can be easily incorporated in coatings for various applications such as anti-corrosion and anti-icing.

Highlights

The variety of structures of nanometric zinc oxide can be classified among new materials with potential applications in various branches of industry: rubber, pharmaceutical, cosmetics, textile, electronic and electrotechnology, photocatalysis, and pro-ecological systems [1,2,3]
The present study focuses on the preparation of modified zinc oxide (ZnO) materials by the sol–gel process using different silane precursors such as (3-glycidyloxypropyl)trimethoxysilane (GPTMS), phenyltriethoxysilane (PhTES), octyltriethoxysilane (OTES), and octadecyltriethoxysilane (ODTES) as modifying agents
Modified ZnO materials were prepared through the sol–gel process using different silica precursors—(3-glycidyloxypropyl)trimethoxysilane (GPTMS), phenyltriethoxysilane (PhTES), octyltriethoxysilane (OTES), and octadecyltriethoxysilane (ODTES)—and were characterized via dynamic light scattering (DLS), environmental scanning electron microscopy (ESEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and roughness and water contact angle analysis

Summary

Introduction

The variety of structures of nanometric zinc oxide can be classified among new materials with potential applications in various branches of industry: rubber, pharmaceutical, cosmetics, textile, electronic and electrotechnology, photocatalysis, and pro-ecological systems [1,2,3]. Li et al [25] modified commercial zinc oxide nanoparticles using APTES and GPTMS as silane coupling agents. The present study focuses on the preparation of modified zinc oxide (ZnO) materials by the sol–gel process using different silane precursors such as (3-glycidyloxypropyl)trimethoxysilane (GPTMS), phenyltriethoxysilane (PhTES), octyltriethoxysilane (OTES), and octadecyltriethoxysilane (ODTES) as modifying agents. The recorded main peak (P1) of ZnO nanoparticles modified with OTES (Sample 3) and ODTES (Sample 4) indicated, in general, smaller particle sizes than those measured for Samples 1 and 2, values of the average diameters (Dm) were much higher, due to the. Roughness and MSE (mean squared error) of ccoatings with ZnO materials modifified with different silane precursors These results are consistent with the conclusion that long organic groups from a silane precursor promote a higher hydroopphhoobbiicciittyy ooff tthhee ssuurrffaacceess. PPrrooffiilleess ooff wwaatteerr ddrroopplleettss ddeeppoossiitteedd oonnttoo mmeettaalllliicc ssuubbssttrraattee,, ccoovveerreedd wwiitthh uunnffuunnccttiioonnaalliizzeedd ZZnnOO ((MM)) aanndd wwiitthh ZZnnOO nnaannooppaarrttiicclleess mmooddiiffiieedd wwiitthh ((11)) GGPPTTMMSS,, ((22)) PPhhTTEESS,, ((33)) OOTTEESS,, aanndd ((44)) OODDTTEESS,, rreessppeeccttiivveellyy

Materials

Synthesis of Modified ZnO-Nanoparticles

Characterization Methods

Findings

Conclusions