Effect of Particle Grafting on Directing Organization Through Polymer Crystallization

It has recently been shown by tuning the crystallization rate of a semicrystalline polymer that grafted nanoparticles (NP) can be forced into interlamellar, interfibrillar, and interspherulitic regions by controlling the isothermal crystallization temperature. Results thus far have demonstrated the ability to tune the fractions of NPs that end up in each region with just temperature. However, crystallization speed and particle mobility are inherently affected by the grafted polymer, used to ensure good initial dispersion in the polymer melt due to the favorable interaction between the graft and matrix. To further study this effect of mobility on the ordering of NPs we vary the graft density of chains on the particle surface, as well as NP size, thereby manipulating their ability to get “pushed” more easily into the various crystal regions. The decrease in effective diameter of these NPs allow for significantly faster crystallization of the surrounding matrix, demonstrated with isothermal DSC experiments. The combination of these effects lead to variations in the NP ordering, as seen with SAXS and TEM. With a variety of nanofillers available, these materials provide a scheme for determining how to optimize the various properties of these trapped-particle composites.