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ERIC Number: EJ1043235
Record Type: Journal
Publication Date: 2014-Oct
Pages: 4
Abstractor: As Provided
Reference Count: 23
ISSN: ISSN-0021-9584
Exploring pH-Sensitive Hydrogels Using an Ionic Soft Contact Lens: An Activity Using Common Household Materials
Chen, Yueh-Huey; He, Yu-Chi; Yaung, Jing-Fun
Journal of Chemical Education, v91 n10 p1671-1674 Oct 2014
Hydrogels of the so-called smart polymers or environment-sensitive polymers are important modern biomaterials. Herein, we describe a hands-on activity to explore the pH-responsive characteristics of hydrogels using a commercially available ionic soft contact lens that is a hydrogel of poly(2-hydroxyethyl methacrylate-"co"-methacrylic acid), poly(HEMA-co-MAA). The observed oscillatory swelling and contracting behaviors of the ionic soft contact lens in response to the changes in solution pH exhibit the reversible pH-responsive property of the hydrogel. Chemical structures of functional groups and the associated intermolecular forces in connection with the physical states of the hydrogel are demonstrated. Solutions of household materials such as vinegar, baking soda, and table salt were used to provide solutions with various conditions. This activity covers the chemistry of polymers and the topics relevant for general chemistry such as molecular interactions, acid-base reaction, solution concentration, and osmosis. The swelling and contracting of the ionic soft contact lens in solutions with various tonicities also make a unique class demonstration for teaching the topic of osmosis due to the quick response of the lens to the environmental solutions.
Division of Chemical Education, Inc and ACS Publications Division of the American Chemical Society. 1155 Sixteenth Street NW, Washington, DC 20036. Tel: 800-227-5558; Tel: 202-872-4600; e-mail:; Web site:
Publication Type: Journal Articles; Reports - Descriptive
Education Level: Higher Education; Postsecondary Education; Secondary Education; High Schools
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A