Morphological study of surface-modified urea–formaldehyde microcapsules using 3-aminopropyltriethoxy silane

In the current study, urea–formaldehyde (UF) microcapsules containing drying oils were prepared by in situ polymerization method. The surface of the prepared UF microcapsules was functionalized by using a silane-coupling agent. Scanning electronic microscopy (SEM), transmission electronic microscopy (TEM), as well as atomic force microscopy observations showed that the surface roughness of the microcapsules has been promoted by the silane treating. Fourier transform infrared spectra and field-emission scanning electron microscopy coupled with energy-dispersive X-ray (EDX) analyses showed that the silane-coupling agent molecular binds strongly to the UF microcapsules surface. The particle size analyzer results show that agglomeration of the treated microcapsules was highly reduced. Thermogravimetric analysis indicated that this modification has improved thermal properties of the microcapsules. The SEM and TEM results indicated the surface roughness is increased after the functionalization treatment, and the silane molecules were attached to the surface of the UF microcapsules. According to EDXA, the weight percent of silicon was increased from 0.95 to 1.25 in the case of increasing the weight percent of the silane-coupling agent from 2 to 5 wt%. In fact, it was concluded that two major factors had influenced the UF microcapsules adhesion into the matrix, which were included as the interfacial bonds between the components and the surface roughness. The heat resistance of the microcapsules had been improved by silane-coupling agent functionalization.