6TH International Congress on Technology - Engineering - Kuala Lumpur3 - Malaysia (2018-07-19)

Synthesis Of Sio2 Core - Acrylic Polymer Shell Composites

Organic–inorganic core-shell composites have attracted great interest for many years since they can be synthesized and monitored by step-by-step procedure [1-4]. They can be tunable through the control of size or functionality at each step [1]. The organic part in the core-shell composites usually improves the flexibility, whereas the inorganic part is responsible for mechanical strength. We reported that silica ball core polymethyl methacrylate shell structured core-shell composites with a single spherical phase can be synthesized at the specific reaction condition and can enhances the surface hardness and antiscratch property when added to clearcoat of vehicle [1-3]. The modified silica ball-acrylate core-shell composites were found to form crosslinks through UV curing and improved the surface mechanical properties [1-4]. Recently, we are interested in modification of surface charge and properties by control of organic core materials. The core-shell composites also exhibit complementary physicochemical properties such as hydrophilicity and hydrophobicity. In this study, multi layered core-shell composites with multiple functions was designed and prepared by a three-step process. First, silica ball particle was synthesized by sol-gel synthesis of water glass silica. Second, the surface was modified by ?-methacryloxy propyl trimethoxy silane to introduce the vinyl group on the silica core. Finally, stearyl acrylate, and behenyl stearate were anchored by copolymerization on the core surface. Each step, particle size and surface zeta potential were analyzed by scattering method (Malvern Instruments Ltd). The thermo gravimetric (TG) data obtained from thermo gravimetric analysis (TGA, Mettler TG50 Thermobalance, nitrogen atmosphere over a temperature range of 20 – 900 ? at a heating rate of 5 ?/min) provide the evidence of core-shell complexation. In the first step, water glass silica(29 wt% SiO2) was ion exchanged using by Amberlite ion exchange resin and further aged in a solution of TEOS/ethanol to strengthen of 3-dimensional network structure [5-7]. The particle size of silica formed was 804.6 ± 270.4 nm. In the second step, the particle size increased to 1027.2 ± 290.2 nm after the anchoring of ?-methacryloxy propyl trimethoxy silane. Grafting of polymer chains to a silica surface by vinyl polymerization leads the formation of core-shell composites and is effective to increase the hydrophobicity of the particles. In the third step, stearyl acrylate or behenyl acrylate were anchored and the size increased more than 1000 nm after copolymerization process. The research regarding on the building applications of polyacrylate/silica nanocomposite has been spotlighted since the uniform dispersal of nano-SiO2 in the polymer can improve the strength and the climate-resistance of the polymer materials [6]. Moreover, superhydrophobic surfaces that water contact angle is more than 150? have shown promising anti-icing performance. When the surface is covered with superhydrophobic core-shell materials, these coatings have only weak adhesion to ice and can be characterized as very icephobic coatings [6-10]. In this study, the hydrophilic/hydrophobic properties of clearcoat were studied when the core shell composites synthesized were added as a filler of clearcoating resin. Table 1. Particle size (nm) and zeta-potential (mV) of SiO2 and SiO2-acrylic polymer shell composites SiO2 SiO2-?MPS SiO2-?MPS-SA SiO2-?MPS-BA Particle size(nm) 804.6±270.4 1027.2±290.2 2756±708 2332.8±753 Zeta potential (mV) -42.2 mV -39.2 mV -3.3 mV 4.2 mV Keywords: Behenyl acrylate/ ?-MPS/SiO2 multi-layer composites, core-shell, clearcoat, zeta potential. References: [1] Kim H. C., Noh S. M., Park S. K.: Synthesis and characterization of nano silica ball - PMMA hybrid composites, J. of Appl. Polym. Sci., 3, 1653-1658 (2013). [2] Noh S.-M., Ahn J.-B., Choi K.-H., Park S. K.: Preparation of Core-Shell Hybrid Compounds by Atomic Transfer Radical Polymerization and its Application to Plastic Lens of Headlamp, J. of Nanosci. and Nanotechnol., 15, 7164-7168 (2015). [3] Noh S. M., Choi K. H., Ji S. J., Hwang Y. K., Park S. K.: Anti-scratch Properties of Clearcoat after Application of Polymer Coated Silica Ball, Asian J. Chem., 25, 5596-5598 (2013). [4] Yazdimamaghani M., Pouvala T., Motamedi E., Fathi B., Vashaee D., Yayebi L.: Synthesis and characterization of encapsulated nanosilica particles with acry;ic copolymer by in situ emulsion polymerization using thermpresponsive non-ionic surfactant, Materials, 6, 3727-3741 (2013). [5] Han I. S., Park J. C., Kim S. Y., Hong K. S., Hwang H. J.: Fabrication and network strengthening of monolithic silica aerogels using water glass, J. Korean Ceramic Soc., 44, 162-168 (2007). [6] Laturkar S. V., Mahanwar P. A.: Superhydrophobic coatings using nanomaterials for antifrost applications – review, NANOSYSTEMS: PHYSICS, CHEMISTRY, MATHEMATICS, 7, 650-656 (2016). [7] Zhao Z. B., Tai L., Zhang D. M., Wang Z. F., Jiang Y.: Preparation of poly (octadecyl methacrylate) /silica-(3-methacryloxypropyl trimethoxysilane)/silica multi-layer core-shell nanocomposite with thermostable hydrophobicity and good viscosity break property, Chem. Eng. J., 307, 891-896 (2017). [8] Golovin K., Kobaku S. P. R., Lee, D. H., DiLoreto E. T., Mabry, J. M., Tuteja A.: Designing durable icephobic surfaces, Surf. Chem., 3, 1-12 (2016). [9] Susoff M., Tai L., Siegmann K., Pfaffenroth C., Hirayama M.: Evaluation of icephobic coatings—Screening of different coatings and influence of roughness, Appl. Surf. Sci., 282, 870-879 (2013). [10] Jafari R., Menini R., Farzaneh M.: Superhydrophobic and icephobic surfaces prepared by RF-sputtered polytetrafluoroethylene coatings, Applied Surface Science., 257, 1540-1543 (2010).
Seung-Kyu Park, Chul-Ho Hong