Synthesis of Rhodamine B-Doped and Monodispersed Spherical Particles of Polyorganosiloxane Using a W/O Emulsion

• Published in: Journal of the American Ceramic Society Vol. 88; no. 12; pp. 3458 - 3468
• Main Authors: Matsumoto, Taichi, Takayama, Yasushi, Onoda, Hiroaki, Kojima, Kazuo, Wada, Noriyuki
• Format: Journal Article
• Language: English
• Published: Malden, USA Blackwell Science Inc 01.12.2005; Blackwell; Wiley Subscription Services, Inc
• Subjects: Applied sciences; Aqueous solutions; Droplets; Dyes; Emulsions; Exact sciences and technology; Inorganic and organomineral polymers; Materials science; Microemulsions; Physicochemistry of polymers; Porosity; Preparation; Rhodamine; Silica; Tables; Transformations; Rhodamine; Water oil emulsion; Heat treatment; Organic dye; Experimental study; Thermal stability; Thermal properties; Structure processing relationship; Sol gel process; Morphology; Preparation; Monodispersed particle; Doped polymer; Spherical particle; Formation mechanism; Siloxane polymer
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/j.1551-2916.2005.00607.x

Rhodamine B (RB)‐doped and monodispersed spherical particles of polyorganosiloxane were synthesized by a sol–gel method from methyltrimethoxysilane (MTMS) using a reaction field of W/O emulsion that was formed from a hydrophobic solution of sorbitantrioleate (SPAN85) plus n‐octane, and an aqueous solution of RB. Three different methods of introducing MTMS into the solution were examined. In the first method, MTMS was added only to the hydrophobic solution of SPAN85 and n‐octane. Although monodispersed spherical particles were synthesized by this method, RB was hardly doped in the spherical particles. In the second method, RB could be doped in spherical particles by introducing MTMS only into the aqueous solution of RB. However, the particle was not monodispersed, and several of pores were present in the particles, which was probably because of a deficiency of silanols in the water droplets in the emulsion. In the third method, above two methods were used together to obtain RB‐doped and monodispersed spherical particles. Moreover, the pores in the particles were remarkably decreased. This is probably because sufficient amounts of silanols were supplied to the water droplets from the oil phase. The content of RB in the particles was different among the three methods. To incorporate RB into the spherical particle, the interaction between RB and silanol was found to play an important role. The RB‐doped spherical particles were heat treated up to 600°C, and the thermal stability of RB was determined. In RB‐doped spherical particles, transformation of T2 into T3 at 200°C was prevented and Si–OH still remained. Fluorescence was still observed in the RB‐doped spherical particles heat treated at a high temperature of 350°C. Therefore, RB was considered to be incorporated tightly into the silica matrix containing Si–CH3. From the above results, we discussed the formation mechanism of RB‐doped spherical particles.