title: Polyurethane-based microparticles: formulation and influence of processes variables on its characteristics.
abstract: This study reports the development of polyurethane-based microparticles and the influence of some processes variables on its characteristics. These microparticles were prepared by emulsion polymerization, using poly(caprolactone) diol (PCL) and poly(propylene glycol), tolylene 2,4-diisocyanate terminated (TDI) or poly(propylene oxide)-based tri-isocyanated pre-polymer (TI). The reaction of polymerization was confirmed by attenuated total internal reflection Fourier transformed infrared spectroscopy (ATR-FTIR). Their thermal characteristics were investigated by dynamical mechanical thermal analysis (DMTA) and thermogravimetric analysis (TGA). For good microparticles formation, formulation 80/20 (mass ratio isocyanate/PCL) was the most indicated. Their spherical shape and smooth surface were observed by optical and scanning electron microscopy (SEM). Zeta potential measurements suggest that ionized carbonyl groups existent at the surface can be responsible for the negative potentials obtained. Respecting size and size distribution of the particles, measured by laser diffraction spectroscopy (LDS), the stirring speed and type were the process variables that most influenced it.
authors.affiliation: Research Centre for Chemical Processes Engineering and Forest Products (CIEPQPF), Department of Chemical Engineering, University of Coimbra, Coimbra, Portugal. elisajcampos@gmail.com
authors.forename: Elisa
authors.initials: E
authors.lastname: Campos
authors.forename: Rosemeyre
authors.initials: R
authors.lastname: Cordeiro
authors.forename: Patrícia
authors.initials: P
authors.lastname: Alves
authors.forename: M G
authors.initials: MG
authors.lastname: Rasteiro
authors.forename: M H
authors.initials: MH
authors.lastname: Gil
mesh_terms: D002244:Carbon / Q000737:chemistry; D002626:Chemistry, Pharmaceutical / Q000379:methods*; D007834:Lasers; D008863:Microspheres; D008956:Models, Chemical; D010087:Oxides / Q000737:chemistry*; D010316:Particle Size; D011108:Polymers / Q000737:chemistry; D011126:Polypropylenes / Q000737:chemistry*; D011140:Polyurethanes / Q000737:chemistry*; D013053:Spectrophotometry; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D013818:Thermogravimetry; D014051:Toluene 2,4-Diisocyanate / Q000737:chemistry*
chemical_list: D010087:Oxides; D011108:Polymers; D011126:Polypropylenes; D011140:Polyurethanes; D014051:Toluene 2,4-Diisocyanate; D002244:Carbon