How Do Repositional Self-Adhesive Paper Notepad Sheets Post-it Notes Work

31 How Do Repositional Self-Adhesive Paper Notepad Sheets (Post-it Notes) Work  

Post-It Notes are ubiquitous forms of communication at the office, in schools, and at home. This extremely useful invention is actually the result of a failed experiment. How does chemistry contribute to the function of this convenient product  

Office supplies and office communication have been revolutionized by the introduction of the 3M product Post-it Notes in 1980. The temporary adhesive of these self-sticking notes actually was initially rejected as a glue by its inventor, 3M chemist Spencer Silver, because of its impermanence. However, 3M researcher Art Fry found a niche for the adhesive — as an adhesive for a temporary bookmark for his choir hymnalJ ] Key to the performance of these removable, repositional adhesive products is the application of the adhesive to the backing of a note sheet via tiny microspheres rather than a continuous film. With an average particle diameter of 25 45 //m, the microsphere adhesives form a discontinuous layer that assists in retaining the ability to re-apply the note to new surfaces. Traditional adhesive tape contains particles of smaller dimension (typically 0.1 to 2.0 y m) that coalesce to form a continuous film that limits removal.t2  

The tacky polymeric microspheres that comprise the pressure-sensitive adhesive layers of repositionable notes are patented inventions. One such material (U.S. Patent 5,714,237) is prepared by a free-radical polymerization reaction of isooctyl acrylate (Fig. 14.3.1) in the presence of polyacrylic acid with a chain- 

Free-radical polymerization reactions are also known as chain-growth or addition polymerization reactions. Let s look at a chain-growth polymerization re- 

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