This research is concerned with nanoparticle design for polymer composites through the discovery of nanoparticle synthesis strategies which provide shape control as well as provide opportunities for concomitant surface functionalization. Specifically, a method to synthesize hydroxyapatite nanoparticles using a dispersed block copolymer template is explored with two different block copolymer chemistries: poly(ethylene oxide)-b-poly(methyacrylic acid) (PEO-b-PMAA) and poly(methyl methacrylate)-b-poly(methyacrylic acid) (PMMA-b-PMAA). Despite differences in the block copolymer chemistry and the solvents used for synthesis, the synthesis proceeded in a similar fashion for both conditions. The shape of the resulting nanoparticle was found to be related to the mole ratio of Ca2+/COO- used during synthesis, and the mole ratios corresponding to the transition from spherical to needle-shape particles was qualitatively consistent between the two block copolymers used. These nanoparticles were incorporated into polymer matrices, and the polymer matrices chosen, PEO and PMMA, matched the outer block of the copolymer coating on the nanoparticle surface. The composites showed relatively homogeneous dispersion at high particle loadings in both systems, and the dynamic moduli were increased with nanoparticle addition both above and below the matrix glass transition temperature. While limited change was seen in the magnitude of the matrix glass transition temperature in both matrices, the crystallinity of the PEO matrix was decreased at high nanoparticle loadings when the nanoparticle spacing was sufficiently small and when the nanoparticle surface area was sufficiently high. Overall, these results suggested that this nanoparticle synthesis scheme is applicable to other block copolymers containing a PMAA block and that the resulting nanoparticles may be successfully utilized in nanocomposites. Additionally, since not all nanocomposite properties are optimized with a single microstructure, developing materials design guidelines for these nanocomposites is relevant to their use in a variety of functional and structural applications.

Copolymer-mediated synthesis of nanoparticles for use in polymer matrix composites

247th National Meeting (2014)

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