Summary: A multidisciplinary team in IRG-1 is developing a new
class of polymeric materials based on reversible hydrogen (H) bonding.
This modular, `lego-like' approach has a large number of advantages
when compared to traditional plastics and elastomers which are based
on covalent bonds. Unlike thermoplastics, these reversible materials
are self-repairing and do not require elevated processing temperatures
to mold. Instead, flow is achieved at much lower temperatures due to
the reversible and tunable nature of the reversible H-bonds. Currently,
some 100 billion pounds of plastics are produced each year in the U.S.
alone and even a small reduction in energy costs for processing would
equate to significant cost and environmental benefits.
Di and tri-block copolymers based on specific H-bonding
motifs have been synthesized and subsequently processed as thin
films into transparent materials that show the characteristic nanoscopic
phase separation of traditional block copolymers. Characterization of
these materials indicates that the reversible chain end bonding groups
are critical to their performance. Significantly, this behavior is predicted
by simulation which also suggests that these self-repairing materials
will have unique properties when compared to traditional systems,
offering great promise for the future.