The widely accepted approach for controlling polymer debonding/bonding properties in responsive materials has been to purposefully engineer the functional end groups responsible for dynamic bonding. In this lecture, however, it will be demonstrated that the debonding temperature of polymer systems constituted of dynamic covalent linkages can also be readily tuned by changing the chain length of the individual polymer building blocks, thus altering the entropy released on debonding. Entropy driven debonding, governed by the building block chain length, is suggested theoretically and experimentally evidenced for two Diels-Alder systems, each based on a different diene/dienophile pairing. In each case a very significant decrease (up to 60 C) in the retro Diels-Alder temperature was observed when the chain length of the difunctional dienophile block is increased. The presented results have the potential to fundamentally change the approach utilized to design materials capable of reversibly bonding on demand.

Harnessing entropy in dynamic covalent macromoleculuar systems

247th National Meeting (2014)

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