(Blacksburg, Va., Aug. 29, 2001) -- Once materials are joined to create a polymer, or plastic, the molecules are traditionally irreversibly linked. This is a concern when a product has reached the end of its useful life and the material cannot be degraded or separated into its components for reuse.
Now, Virginia Tech researchers are reversing the irreversible.
In a presentation at the American Chemical Society's 222nd national meeting, Aug. 26-30 in Chicago, researchers will talk about polymers that can be reversed, or disconnected, using heat.
"We are using hydrogen bonding in combination with living polymerization techniques to create polymer molecules with well-defined, reversible architectures," explains Tim Long of Virginia Tech's chemistry department. "If you glue something together at the molecular level, you should be able to take it apart."
The researchers are most interested in thermoplastic elastomers (TPE), a rubbery material based on block co-polymers -- polymer molecules created by linking long units of first one component or monomer, then another. "Another exciting application would be new adhesives that could simply be reversed with heat," says Long.
In a talk on "Synthesis and characterization of telechelic multiple hydrogen-bonded polymers via living anionic polymerization (PMSE 278), Koji Yamauchi, a visiting international scientist from Toray Industries in Japan, will talk about his and Long's work to synthesize nano-phase separated polystyrene and polyisoprene based materials containing reversible linkages.
In addition to the controlled synthesis of the novel copolymers, the melt viscosity behavior, morphology, and hydrogen bond dissociation temperatures will be described. The researchers monitored the entire process in real-time using in-situ infrared spectroscopy.
Yamauchi will present his research on Wednesday, Aug. 29, at 2:30 p.m., in McCormick Place South Room S103A, Level 1.