Asymmetric Colloidal Janus Particle Formation Is Core-Size-Dependent

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• 作者：Preston B. Landon ; Alexander H. Mo ; Adam D. Printz ; Chris Emerson ; Chen Zhang ; Woraphong Janetanakit ; David A. Colburn ; Siddhartha Akkiraju ; Samuel Dossou ; Baxi Chong ; Gennadi Glinsky ; Ratnesh Lal
• 刊名：Langmuir
• 出版年：2015
• 出版时间：August 25, 2015
• 年：2015
• 卷：31
• 期：33
• 页码：9148-9154
• 全文大小：514K
• ISSN：1520-5827

文摘

Colloidal particles with asymmetric surface chemistry (Janus particles) have unique bifunctional properties. The size of these particles is an important determinant for their applications in diverse fields from drug delivery to chemical catalysis. The size of Janus particles, with a core surface coated with carboxylate and a partially encapsulating silica shell, depends upon several factors, including the core size and the concentration of carboxylate coating. The role of the carboxylate coating on the Janus particle size is well-understood; however, the role of the core size is not well defined. The role of the carboxylated polystyrene (cPS) core size on the cPS鈥搒ilica Janus particle morphology (its size and shape) was examined by testing two different silica sizes and five different cPS core sizes. Results from electron microscopy (EM) and dynamic light scattering (DLS) analysis indicate that the composite cPS鈥搒ilica particle acquires two distinct shapes: (i) when the size of the cPS core is much smaller than the non-cPS silica (b-SiO₂) sphere, partially encapsulated Janus particles are formed, and (ii) when the cPS core is larger than or equal to the b-SiO₂ sphere, a raspberry-like structure rather than a Janus particle is formed. The cPS鈥搒ilica Janus particles of 鈭?00鈥?00 nm size were obtained when the size of the cPS core was much smaller than the non-cPS silica (b-SiO₂) sphere. These scalable nanoscale Janus particles will have wide application in a multifunctional delivery platform and catalysis.