Synthesis of Nonspherical Colloidal Particles with Anisotropic Properties

• Published in: Journal of the American Chemical Society Vol. 128; no. 44; pp. 14374 - 14377
• Main Authors: Kim, Jin-Woong, Larsen, Ryan J., Weitz, David A.
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 08.11.2006
• Subjects: Chemistry; Exact sciences and technology; General and physical chemistry; Molecular flexibility; Seeds; Ethylene; Polymerization; Hydrophobic compound; Polymer; High temperature; Imine; Surfactant; Amphiphilic compound; Colloid; Surface treatment; Styrene derivative polymer; Anisotropy; Bulb; Phase separation; Plant origin; Surface properties; Hydrophilic compound; Chemical synthesis; Below ground plant part
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja065032m

We describe a promising and flexible technique for fabricating uniform nonspherical particles with anisotropic phase and surface properties. Our approach is based on the seeded polymerization technique in which monomer-swollen particles are polymerized. The polymerization causes a phase separation to occur, giving rise to two-phase nonspherical particles. We show that the elastic contraction of the swollen polymer particles induced by elevated polymerization temperatures plays an important role in the phase separation. Moreover, chemical anisotropy of nonspherical particles can be obtained by using immiscible polymer pairs and by employing surface treatments. Furthermore, we are able to produce amphiphilic dumbbell particles consisting of two different bulbs:  hydrophilic poly (ethylene imine)-coated polystyrene and hydrophobic polystyrene. Controlled geometries of these amphiphilic nonspherical particles will allow a wide range of potential applications, such as engineered colloid surfactants.