1 research outputs found
Role of Surface-Grafted Polymers on Mechanical Reinforcement of Metal–Organic Framework–Polymer Composites
Utilizing metal–organic frameworks (MOFs) as reinforcing
fillers for polymer composites is a promising strategy because of
the low density, high specific modulus, and tunable aspect ratio (AR).
However, it has not been demonstrated for the MOF-reinforced polymer
composite using MOFs with high AR and polymer-grafted surface, both
of which are extremely important factors for efficient load transfer
and favorable particle–matrix interaction. To this end, we
designed an MOF–polymer composite system using high AR MOF
PCN-222 as the mechanical reinforcer. Moreover, we developed a synthetic
route to graft poly(methyl methacrylate) (PMMA) from the surface of
PCN-222 through surface-initiated atomic transfer radical polymerization
(SI-ATRP). The successful growth of PMMA on the surface of PCN-222
was confirmed via proton nuclear magnetic resonance
and infrared spectroscopy. Through thermogravimetric analysis, the
grafting density was found to be 0.18 chains/nm2. The grafted
polymer molecular weight was controlled ranging from 50.3 to 158 kDa
as suggested by size exclusion chromatography. Finally, we fabricated
MOF–polymer composite films by the doctor-blading technique
and measured the mechanical properties through the tension mode of
dynamic mechanical analysis. We found that the mechanical properties
of the composites were improved with increasing grafted PMMA molecular
weight. The maximum reinforcement, a 114% increase in Young’s
modulus at 0.5 wt % MOF loading in comparison to pristine PMMA films,
was achieved when the grafted molecular weight was higher than the
matrix molecular weight, which was in good agreement with previous
literature. Moreover, our composite presents the highest reinforcement
measured via Young’s modulus at low weight
loading among MOF-reinforced polymer composites due to the high MOF
AR and enhanced interface. Our approach offers great potential for
lightweight mechanical reinforcement with high AR MOFs and a generalizable
grafting-from strategy for porphyrin-based MOFs