Polymer functionality greatly determines many of the key properties of these materials, such as glass-transition temperature, electrical and thermal conductivity, thermal stability, mechanical strength, and processability. Despite the importance of polymer functionality in determining material properties, the synthesis of functional polymers, with well-defined molecular weights and compositions, can still present a significant challenge, with many of the methods related to pre- or postpolymerization modification lacking synthetic scope, or requiring harsh functionalization conditions or transition-metal coupling reactions to install the desired functionality. Perfluoroaromatic systems are promising for the preparation of novel polymer architectures given that they can be readily functionalized using simple nucleophilic chemistries under very mild basic conditions. While promising, these systems have displayed some drawbacks. Previous work has shown that perfluoroaromatics, such as perfluoropyridine, can demonstrate a high degree of chemical reversibility with heteroatom nucleophiles. If the synthetic potential of these systems is to be realized, then a strategy for the rational design of stable monomers must be developed. Herein, we report the design, synthesis, and characterization of a series of unexplored heteroatom-based ring-opening metathesis polymerization (ROMP)-active monomers containing a reactive perfluoropyridine pendent group, which can be used to readily prepare a wide variety of aryl ether-functionalized polymers, using both pre- and postpolymerization modification strategies. We also establish a direct connection between the dihedral angle of the monomer and its propensity to undergo reversible addition reactions, establishing functional criteria for the design of pre- and postmodifiable systems.

No abstract

Improvements to fluoropolymer processing techniques by way of utilizing nanoparticles as drop-in processing aids have pronounced effects on bulk composite properties. In this work, we prepared fluoroalkyl-silanized silica nanoparticles (F-SiNPs, ca. 200 nm) that were solvent-blended with polyvinylenedifluoride (PVDF) in order to prepare composites with varying weight fractions. We demonstrated that the ability to functionalize SiNPs with long fluoroalkylchains that induced co-crystallization with the PVDF matrix, resulting in uniform particle dispersion and improved interlaminate adhesion. This was quantitatively investigated using calorimetry and thermogravimetric analysis, which showed a decrease in the bulk crystallinity of the virgin PVDF from 37% to 10% with minimal 10 wt % F-SiNP loading, rendering a nearly amorphous PVDF. Additional discussions in this work include the effects of various bare and fluoroalkyl-functionalized SiNP loadings on the amorphous and crystalline domains of the PVDF matrix, as well as thermal decomposition.