Hierarchical Structure in Semicrystalline Polymers Tethered to Nanospheres
KAUST Grant NumberKUS-C1-018-02
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AbstractWe report on structural and dynamic transitions of polymers tethered to nanoparticles. In particular, we use X-ray diffraction, vibrational spectroscopy, and thermal measurements to investigate multiscale structure and dynamic transitions of poly(ethylene glycol) (PEG) chains densely grafted to SiO2 nanoparticles. The approach used for synthesizing these hybrid particles leads to homogeneous SiO2-PEG composites with polymer grafting densities as high as 1.5 chains/nm2, which allows the hybrid materials to exist as self-suspended suspensions with distinct hierarchical structure and thermal properties. On angstrom and nanometer length scales, the tethered PEG chains exhibit more dominant TTG conformations and helix unit cell structure, in comparison to the untethered polymer. The nanoparticle tethered PEG chains are also reported to form extended crystallites on tens of nanometers length scales and to exhibit more stable crystalline structure on small dimensions. On length scales comparable to the size of each hybrid SiO 2-PEG unit, the materials are amorphous presumably as a result of the difficulty fitting the nanoparticle anchors into the PEG crystal lattice. This structural change produces large effects on the thermal transitions of PEG molecules tethered to nanoparticles. © 2014 American Chemical Society.
CitationKim SA, Archer LA (2014) Hierarchical Structure in Semicrystalline Polymers Tethered to Nanospheres. Macromolecules 47: 687–694. Available: http://dx.doi.org/10.1021/ma4019922.
SponsorsThis work was supported by the National Science Foundation, Award DMR-1006323, and by Award KUS-C1-018-02, made by King Abdullah University of Science and Technology (KAUST). Facilities available though the Cornell Center for Materials Research (CCMR) were used for this study (DMR-1120296). The authors thank Dr. Ivan Keresztes for the help with the NMR experiment.
PublisherAmerican Chemical Society (ACS)