4(%3)3 - Ecole nationale supérieure de chimie de Montpellier

181614SP2 - iNumber of Particles12108642SP2 - ii02535455565758595105115125135145155178188198208218228238248258268278288Particle Diameter (nm)Figure – 3.9: Bimodal size distribution obtained for silica nanoparticles (SP2) showing two population of NPsUnlike the monomodal distribution of poly(styrene) NPs, both series of silica NPs showed abimodal distribution (Figure – 3.8 & 3.9). The average diameters of the NPs were calculated usingequation – 3.1 by measuring the diameters of individual NPs in SEM images (Figure – 3.10a,b,c,d)obtained for both series. The average mean diameters thus obtained for two populations of both theseries have been presented in the table – 3.1. The SP1 series silica particles comprised an approximate56.7 % of smaller silica particles while SP2 series comprised 61 % of smaller NPs.Average MeanDe Brouckere MeanDispersityNanoparticlesDiameter (D a )Diameter (D b )IndexPercentage(nm)(nm)(D b /D a )of NanoparticlesSilica SP1 – i 156 167 1,07 57Silica SP1 – ii 279 293 1,05 43Silica SP2 – i 88 94 1,07 61Silica SP2 – ii 223 230 1,03 39Table – 3.1: Various diameters, dispersity indices and relative % of silica nanoparticles calculated from ScanningElectron Microscopy images. 200 particles were counted for each type of population.82