- Nano Express
- Open Access
Raspberry-like PS/CdTe/Silica Microspheres for Fluorescent Superhydrophobic Materials
© Chang et al. 2016
- Received: 14 August 2015
- Accepted: 19 February 2016
- Published: 29 February 2016
Superhydrophobic particulate films were fabricated via deposition of raspberry-like fluorescent PS/CdTe/silica microspheres on clean glass substrates and surface modification. Particularly, the fluorescent microspheres were prepared by a kind of modified strategy, namely introducing poly (acrylic acid)-functionalized polystyrene microspheres and thiol-stabilized CdTe quantum dots into a hydrolysis reaction of tetraethoxysilane simultaneously. And through adjusting the reaction parameters, the polystyrene spheres with two particle sizes and three colors of CdTe quantum dots aqueous solution were obtained. Consequently, raspberry-like microspheres consist of polystyrene cores and the composite shells of CdTe quantum dots and silica. These microspheres possess a fluorescent characteristic and form a hierarchical dual roughness which was conductive to superhydrophobicity, and the hydrophobic tests also showed the contact angles of water droplets on the surface of the raspberry-like microspheres which were over 160° at room temperature.
- Polystyrene microspheres
- Particulate films
Considerable attention has been paid to the wettability of solid surfaces due to its importance in the deep understanding of interface chemistry and the precise manufacture of surface microstructures as well as its great potential for fundamental and industrial applications [1–4]. Unfortunately, because of the expensiveness, instability, and fragility of the related materials and end-product films, most of these cases have difficulty in practical applications . In recent years, polymer/silica raspberry-like particles synthesized in hydrolysis reactions for large-scale superhydrophobic materials have aroused much interest [6–9]. Meanwhile, some jobs have been reported on the synthesis of aqueous CdTe/silica composite particles in a hydrolysis reaction to maintain the fluorescent stability of aqueous CdTe quantum dots (QDs) [10, 11].
Herein, after studying the methods for preparation of polymer/silica raspberry-like particles  and the synthesis of aqueous CdTe/silica composite particles , we combined the two hydrolysis reactions into a simple process to prepare raspberry-like microspheres by introducing poly (acrylic acid) (PAA)-functionalized polystyrene (PS) microspheres and thioglycolic acid (TGA)-stabilized CdTe QDs into a hydrolysis reaction of tetraethoxysilane (TEOS). The monodispersed PAA-functionalized PS microspheres were used as cores, and tiny silica particles with CdTe QDs enfolded and then assembled on the surface of PS microspheres to construct raspberry-like microspheres during the hydrolysis process. Subsequently, the particulate films were constructed by depositing these raspberry-like fluorescent microspheres on clean glass substrates. After surface modification with fluoroalkyl-silane (FAS), superhydrophobic surfaces were obtained.
The morphologies of CdTe QDs, PS microspheres, and PS/CdTe/silica fluorescent microspheres were characterized by TEM (FEITECNAI F20) and scanning electron microscope (SEM, S-4800), respectively. The crystallization of CdTe QDs was investigated by X-ray diffraction (XRD, D8 advance). Contact angle measurements for samples were performed using a contact angle meter (OCA20, Dataphysics) by placing a water droplet (~7 μL) on the surface of samples.
In this study, the particulate films consisted of raspberry-like PS/CdTe/silica microspheres which were prepared via the use of functional PS spheres as the growing cores and the hydrolysis process. Due to the fluorescent characteristic of CdTe QDs and the modification with FAS, the films displayed three different colors under UV rays and their surface became hydrophobic. It is well known that the hierarchical structure was beneficial to hydrophobic property. Therefore, the contact angles of water droplets on particulate films could reach 163.2°. Furthermore, the materials for constructing this kind of dual-sized structured films have the advantages of low cost, stable fluorescence, and large-scale fabrication, which can make it a good candidate for the achievement of optical functional hybrid wettability surfaces.
The present study has been supported by the National Natural Science Foundation of China (grant no. 51273056, 51473046, 21202091, 51303045, and 51372072), the Natural Science Foundation of Heilongjiang Province (grant no. 1254-NCET-024), Abroad Person with Ability Foundation of Heilongjiang Province (grant no. 11551339, 12521400, and 1252CGZH09), China Postdoctoral Science Foundation (2014 M561545), Heilongjiang Province Postdoctoral Science Foundation (grant no. LBH-Q12021 and LBH-Q09032), and Heilongjiang Provincial Department of Education (grant no. 12521398).
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