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Name Mr. Sachit Shah
Organization or Institution University of Central Florida
Presentation Type Poster

Thermo-responsive Polyelectrolyte Complex Micelles


Sachit Shah, Lorraine Leon

Author Institution(s)

University of Central Florida


Polyelectrolyte Complexes form by mixing two oppositely charged polymers in solution. This phenomenon results in either complex coacervation which is a liquid-liquid phase separation or solid precipitate formation Electrostatic interaction between a diblock copolymer of a neutral block and a charged block, with an oppositely charged polymer leads to the formation of polyelectrolyte complex (PEC) micelles. The micelles formed have a polyelectrolyte complex core, while the neutral block forms the corona. PEC micelles have applications in nucleic acid delivery, where the negatively charged nucleic acid serves as the polyanion. This work explores using a thermosensitive polymer a poly(N-isopropyl acrylamide)(pNIPAM) as the neutral block. pNIPAM has a lower critical solubility temperature, above which a hydrophilic to hydrophobic transition occurs. This transition could lead to a core-corona inversion, that could facilitate the release molecules within the polyelectrolyte core leading to potential applications in controlled release drug delivery. We have developed a system using a poly(N-isopropyl acrylamide)-poly(acrylic acid) (pNIPAM-pAA) diblock copolymer and poly(L-lysine). The morphology and stability of these micelles is studied in varying solution conditions of salt concentration, pH, and temperature, which are all parameters known to affect polyelectrolyte complex formation. Additionally, the polymer charge concentration is varied to investigate its effects on micelle morphology. Techniques of dynamic light scattering and small-angle x-ray scattering are being used to study micelle architecture, before and after temperature transition. Preliminary results indicate that micelles begin to aggregate above the LCST transition, but it is unclear if the core and corona segments demix after the transition. Future work involves, using small angle neutron scattering with deuterated pNIPAM in order to verify if a true core-corona inversion is occurring.