Block Copolymer Definition (Chemistry)

Nitrile, a plastic commonly used in disposable gloves, is a block copolymer.
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A block copolymer is a copolymer formed when the two monomers cluster together and form 'blocks' of repeating units.

For example, a polymer made up of X and Y monomers joined together like:

-Y-Y-Y-Y-Y-X-X-X-X-X-Y-Y-Y-Y-Y-X-X-X-X-X-

is a block copolymer where -Y-Y-Y-Y-Y- and -X-X-X-X-X- groups are the blocks.

Block Copolymer Examples

The material used to make automobile tires is a block copolymer called SBS rubber (acrylonitrile butadiene styrene). The blocks in SBS rubber are polystyrene and polybutadiene (StyreneButatineStyrene). Nitrile and ethylene-vinyl acetate are also copolymers.

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Helmenstine, Anne Marie, Ph.D. "Block Copolymer Definition (Chemistry)." ThoughtCo, Aug. 27, 2020, thoughtco.com/definition-of-block-copolymer-604834. Helmenstine, Anne Marie, Ph.D. (2020, August 27). Block Copolymer Definition (Chemistry). Retrieved from https://www.thoughtco.com/definition-of-block-copolymer-604834 Helmenstine, Anne Marie, Ph.D. "Block Copolymer Definition (Chemistry)." ThoughtCo. https://www.thoughtco.com/definition-of-block-copolymer-604834 (accessed May 12, 2021).