Event Information
The Effect of gem-Dichlorocyclopropane Mechanophore on the Macroscopic Mechanical Properties of Polymers
- Abstract:
Toughness is an important property of materials that shows how much energy a material can absorb before rupture. It has been demonstrated that the toughness of a gem-dibromocyclopropane (gDBC) functionalized polybutadiene single polymer chain is greater than that without the gDBC mechanophores, due to the electrocyclic ring opening reaction of gDBC into 2,3-dibromoalkenes that occurs under mechanical load. Our goal is to determine whether this molecular mechanical property can also be manifested in bulk material properties. Crosslinked gem-dichlorocyclopropane (gDCC) embedded polybutadiene polymers were swollen in various solvents and mechanically deformed under tensile stress. Modulus and fracture toughness were compared among polybutadienes with different percentages of mechanophore incorporated. The temporary results showed that the incorporation of gDCC does not increase the fracture toughness of the corresponding crosslinked polybutadiene polymers. Based on the NMR characterization of the post-test samples, there was no detectable activation of the gDCC in the crosslinked polybutadiene backbones. Further experiments will be focused on optimizing the material structures, i.e. relocate the mechanophores in the crosslinking positions and continuing exploring the correlation between molecular responses and changes in macroscopic properties. In the same time, we will keep exploring the force induced crosslinking through nucleophilic displacement reaction by incorporating good nucleophile in the polymer backbones and see whether the crosslinking density will increase and how it affects the material’s mechanical properties.
Preliminary Examination Seminar
Student Exams Seminar