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Márta Rózsahegyi

Department of Inorganic and Analytical Chemistry, L. Eötvös University, Pázmány s. 1/a, H-1117 Budapest, Hungary

Károly Mazák

Institute of Pharmaceutical Chemistry, Semmelweis University, H-1092 Budapest, Hungary

Sándor Szabó L.

Chemical Research Center, Hungarian Academy of Sciences, POB 17, H-1525 Budapest, Hungary

Dezsö Knausz

Department of General and Inorganic Chemistry, L. Eötvös University, H-1117 Budapest, Hungary

J. Chem. Educ., 2001, 78 (3), p 329

DOI: 10.1021/ed078p329

Publication Date (Web): March 1, 2001

Abstract

These experiments present the "hydrophobizing" and organophilic properties of silicones. The method is to make hydrophobic the polar, hydrophilic surface of glass by silylating the surface of various glass objects with trimethylsilyl N,N-dimethylcarbamate. The process of activating and silylating glass beads, capillaries, beakers, and glass sheets is described. Classroom demonstrations are presented on the different behaviors of the silylated and simply activated surfaces of these glass objects interacting with distilled water, and in the case of capillaries, also with hexane and ethanol. Spherical water drops can be observed on the hydrophobic microscope slide. Silylated glass beads float on the surface of water, displaying different patterns. They also remove oil contamination from the surface of water. The capillaries show different capillary action toward water and hexane. These experiments can enrich the coverage of silicon compounds in the classroom and make them more familiar to children.