Conclusion
In summary, we successfully
synthesized three hyperbranched structures with a common Si-O-C
molecular backbone but differing terminal groups. These structures were
co-crosslinked with thermoset epoxy to explore their terminal effects on
affecting the overall material performance. The special molecular
characteristics of HBPSi-R involves abundant -OH groups for their
reactiveness, as well as distinctive terminals (-NH2,
-EP, vinyl groups) that impart characteristic interface features. All
three variants of HBPSi-R exhibit well compatibility within the epoxy
matrix, showcasing diverse nano-interface and aggregation behavior.
Benefiting their spatial molecular configuration and flexible Si-O-C
branches, HBPSi-R manifests exceptional strengthening and toughening
effects regardless of their terminal groups. Among them,
HBPSi-NH2 predominantly exhibits the aggregation
behavior from supramolecular interaction, while HBPSi-EP show
predominantly exhibits dispersion behavior from covalent effect. HBPSi-V
achieves a balance of the both, surpassing the other two structures in
terms of optimal impact toughness (28.9 kJ mol-1) and
better mechanical performance under high dosage, where the non-reactive
vinyl group acts as a supportable role during polymer crosslinking.
These findings not only emphasize the pronounced reinforcement effects
of HBPSi-R but also provide a fresh perspective from aggregate science
in the context of polymer crosslinking.