Different Strategies to Synthesize Hybrid Nanogels by Photopolymerization Employing Conjugated Polymers Nanoparticles and Silsesquioxanes

CAGNETTA, G.; M. L. GOMEZ; GALLASTEGUI, A.; C. A. CHESTA; PALACIOS R

Viña del Mar

Congreso; XIV Elafot; 2019

The design and preparation of nanogels have attracted a great deal of interest in biomedical engineering, pharmaceutical applications, and in biomaterials science. Nanogels have certain advantages over macro hydrogels such as: controlled administration of bioactive agents at specific sites, low toxicity, and high biocompatibility, among others1. On the other hand, nanogels can be combined with other materials to generate hybrid systems and thus improve and/or establish better specific properties. Among all the synthesis paths to achieve nano materials, inverse mini emulsion polymerization seems to be the most used technique to synthesize nanogels from hydrophilic monomers2. Nevertheless, the employment of organic solvents and the use of surfactants represent disadvantages associated to this technique. Because of these drawbacks, some new techniques have been investigated to overcome these issues. In this work two different successful ways to synthesize nanogels are presented: inverse mini emulsion photopolymerization and precipitation. In both cases conjugated nanoparticles as macrophotoinitiators (CPNPs) were employed.Nanogels of 2-methacryloyloxy ethyl trimethyl ammonium chloride (METAC) and 2-hydroxyethyl methacrylate (HEMA) containing a silsesquioxane precursor in their structure that act as crosslinker and co-iniciator were synthesized by both methods. The photoinitiator system consists of conjugated polymers nanoparticles of F8BT or PFO. Also, monomer, surfactant, crosslinker and CPNPs concentrations were varied to obtain nanogels with different diameter by both methods.CPNPs have the capacity to absorb and emit radiation in the visible region of the electromagnetic spectrum; and to participate as an electron transfer agent, thus initiating the polymerization by visible light without a sensitizer. In addition, CPNPs are retained in the nanogel matrix after polymerization, which represents an advantage for the application of these materials in fluorescent imaging3.Nanogels were characterizad through DLS (Dynamic Light Scattering), TEM (Transmition Electron Microscopy), SEM (Scaning Electron Microscopy), UV-visible spectroscopy, Fluorescence spectroscopy, Individual particle fluorescence microscope, among others.Nanogels of ∼120 nm diameter of poly-HEMA were obtained by inverse mini emulsion polymerization, however an exhaustive process of dialysis is necessary to eliminate all surfactant. On the other hand, nanogels of ∼150 nm diameter of poly-METAC were obtained by direct irradiation of solution containing CPNPs and monomers. All synthesized nanogels maintain intact CP properties, as confirm by spectroscopic characterization.At the present microbiological experiments with poly-METAC nanogels are being performed to corroborate their antifouling activity.