10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
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Production of Cauliflower-like Amphipathic Copolymer Nanoparticles using Aerosol-Photopolymerization
Masoom Shaban, Jalal Poostforooshan, ALFRED P. WEBER, TU Clausthal
Abstract Number: 704 Working Group: Aerosol Chemistry
Abstract Amphipathic copolymers consist of hydrophilic and hydrophobic monomer units have attracted great technological attention recently, owing to their unique properties and their ability to stabilize various interfaces in aqueous systems. However, producing these copolymers is still a great challenge in liquid phase due to different polarities of monomers. As a promising alternative to the conventional liquid methods, the polymer nanoparticles can be prepared by an aerosol-polymerization. This method can also avoid the requirement of surfactants and solvents, and produce directly solvent-free dry powders with a high purity and spherical morphology in a continuous process which is desirable in pharmaceutical applications.
The work presented here describes a continuous aerosol-photopolymerization to produce different kind of spherical polymer nanoparticles including polyacrylamide (PAM), polystyrene (PS) and hydrophobically modified polyacrylamide (HM-PAM) [1]. The experimental setup is a combination of an atomizer, a homemade flow-through photoreactor, and a collection filter. Initially, the monomer droplets consisting of dissolved photoinitiator were generated by the atomizer. Then, sprayed droplets were passed through the photoreactor, where the free radicals were generated upon UV irradiation within the average aerosol residence time of 30 s in the photoreactor. To control the aqueous solubility, size and morphology of the resulting HM-PAM copolymers, different styrene/acrylamide monomer concentrations were introduced into the system.
The textural properties of the obtained materials were characterized by TEM, SEM, and N2 adsorption-desorption isotherms. The results revealed that the copolymers and polyacrylamide have cauliflower-like morphologies, while polystyrene has a nearly smooth morphology. Moreover, chemical compositions of the obtained materials were investigated by several characterization techniques such as 1H NMR, FT-IR, TGA and elemental analysis. 1H NMR and elemental analysis of resulting copolymers microstructures displayed successful incorporation of styrene in the copolymer with a good agreement compared to initial ratios.
Importantly, the final particle size of resulting polymer nanoparticles could be controlled either by the concentration of solution or flow rate of the carrier gas. As an example, the nanospheres generated with the total initial concentration of 0.195 M and 0.468 M, lead to the average size of 103 nm and 199 nm, respectively.