Fine-tuning of functional poly(methylmethacrylate) nanoparticle size at the sub-100 nm scale using surfactant-free emulsion polymerization

Functional poly(methylmethacrylate) (PMMA) nanoparticles are of great use in various research areas from photonic band gap materials to biomolecule delivery vehicles. Herein, we introduce a conventional surfactant-free emulsion polymerization (SFEP) method that enables the production of functional sub-100 nm PMMA nanoparticles without the need of microwave irradiation. Cross-linked PMMA latex having monodisperse size distribution can be prepared. Particle characterization studies were carried out using dynamic light scattering (DLS). Spherical and uniformly sized nanoparticles were observed by scanning electron microscopy (SEM). Stable cationic PMMA nanoparticle dispersions were obtained for all formulations where the particle charge stems from the amidine initiator. The presence of the amidine moieties was confirmed by using an isothiocyanate containing fluorophore. An important appealing feature of this method is the ability to fine-tune the resultant particle size at the sub-100 nm scale by simply varying the monomer concentration.