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<p>Toughness, the measure of how much energy a material can absorb before rupture,
is an important property of materials. It has been demonstrated that the toughness
of a single polymer chain of <italic>gem</italic>-dihalocyclopropane (<italic>g</italic>DHC)
functionalized polybutadiene (PB) is increased dramatically over PB alone, due to
the mechanically triggered electrocyclic ring opening reaction of <italic>g</italic>DHC
into 2,3-dibromoalkenes. This thesis explores whether this molecular mechanical property
can also be manifested in bulk material properties. Crosslinked <italic>gem</italic>-dichlorocyclopropane
(<italic>g</italic>DCC) embedded PB polymers were swollen in various solvents, and
the resulting gels were mechanically deformed under tensile stress. Young's modulus
and fracture toughness were compared among PBs with <italic>g</italic>DCC incorporated
in the backbones and/or crosslinking positions. The results showed that the incorporation
of <italic>g</italic>DCC does not measurably increase the fracture toughness of the
crosslinked polymer gels. Neither NMR nor FT-IR characterization of the post-test
samples revealed detectable activation of the <italic>g</italic>DCC in the crosslinked
PB. Further experiments will be focused on optimizing the polymer structure and testing
methods to more effectively transfer the macroscopic force to the mechanophore in
the material and continuing exploring the correlation between molecular responses
and changes in macroscopic properties.</p>
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