The self-assembling properties of a core-shell system are considered to be the most desirable characteristics that allow using this class of polymers in different applications. New hairy nanoparticles (HNPs) with hydrophobic polystyrene cores (PS Cores) and hydrophilic poly(2-hydroxyethylmethacrylate) (PHEMA) shells were synthesized by coupling polymerization methods. Living anionic polymerization in one-pot step was used to synthesize cross-linked polystyrene cores functionalized with hydroxyl groups and atom transfer radical polymerization (ATRP) was then carried out to prepare PHEMA hairs following the grafting form technique. The structural characterizations were carried out by FT-IR and NMR spectroscopy (1H NMR, 13C NMR, APT 13C NMR and 1H 13C HMQC). Dynamic light scattering measurements of obtained HNPs show small increase in the order of nanometers of their hydrodynamic radii after the grafting. Thermal properties were studied by TGA and DSC. The thermal stability of PS cores was affected by functionalization with the hydroxyl group. However, the stability of the PS core was not affected by grafting of PHEMA on their surfaces. DSC thermograms of the HNPs shows two distinct transition temperatures corresponding to glass transition temperatures (Tg) of a PS phase and of a PHEMA phase indicating the formation of a hydrophobic-hydrophilic phase separated system. SEM and AFM were utilized to study the morphologies and self-assembly of nanoparticles. The self-assembled HNPs morphologies were dependent on the solvents used.
Complexes of the synthesized HNPs and R- or S-mandelic acid were prepared and characterized by circular dichroism (CD) and AFM. CD was used to study the induced chiral properties of the complexes. The CD spectra indicated the formation of enantiomeric chiral structures and the AFM images show toroidal self-assembled structures. Polymer blends of polystyrene functionalized with hydroxyl groups and PHEMA show different morphology and different thermal properties than the core-shell HNP system.
| Identifer | oai:union.ndltd.org:auctr.edu/oai:digitalcommons.auctr.edu:cauetds-1319 |
| Date | 20 May 2019 |
| Creators | Habel, Azza |
| Publisher | DigitalCommons@Robert W. Woodruff Library, Atlanta University Center |
| Source Sets | Atlanta University Center |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Electronic Theses & Dissertations Collection for Atlanta University & Clark Atlanta University |
Page generated in 0.0019 seconds