Spherical mesoporous silica nanoparticles/tailor-made polystyrene nanocomposites by in situ reverse atom transfer radical polymerization

Abstract

Spherical mesoporous silica nanoparticles (MCM 41)/tailor made polystyrene nanocomposites were synthesized by in situ reverse atom transfer radical polymerization. Characteristics of spherical MCM 41 nanoparticles were evaluated by nitrogen adsorption/desorption isotherm and X ray diffraction. Morphological studies were also performed by scanning and transmission electron microscopy. Conversion and molecular weight evaluations were carried out using gas and size exclusion chromatography respectively. Addition 3 wt% of MCM 41 nanoparticles results in a decrease in conversion from 89 to 53%. Similar reduc tion behavior is also observed for molecular weight of the nanocomposites. However, polydispersity indices (PDI) values increase from 1.42 to 2.07 by the only 3 wt% addition of MCM 41 nanoparticles. A peak around 4.1 ppm which originates from hydrogen atom of terminal units of polymer chains in 1 H NMR spectra in combination with low PDI values can appropriately demonstrate the living nature of the polymerization. Thermogravimetric analysis shows that thermal stability of the nanocomposites is higher than the neat poly styrene and increases by increasing MCM 41 nanoparticles content. Glass transition temperature decreases by the addition of MCM 41 nanoparticles loading as revealed by differential scanning calorimetry results.

A study of some fundamental physicochemical variables on the morphology of mesoporous silica nanoparticles MCM-41 type

“…Although silicon dioxide is an amorphous material, mesoporous inside MSN may be analyzed as if they were organized in a unit cell and measured by SAXRD, as shown in Figure 9a. Three well resolved peaks were found: one sharp and intense peak around 2 from 2.0° to 2.5°, and two other less intense peaks between 2 from 3.5° to 5.0°, as expected for MCM-41 (Khezri et at. 2014).…”

“…An important disagreement among literature is related with the appearance of a hysteresis loop between adsorption and desorption curves. Many authors attribute this loop as a proof of the existence of mesoporosity for MCM-41 (Ukmar et al 2011;Zhou et al 2016), while others reports indicate that it is actually the absence of hysteresis, which suggests the formation of uniform cylindrical mesopores inside the nanoparticle (Bernardos et al 2010;Khezri et at. 2014).…”

SR&NI atom transfer radical random copolymerization of styrene and butyl acrylate in the presence of MPS-functionalized silica aerogel nanoparticles

“…(2) As shown in Fig. 2, some of the hydroxyl groups on the surface of hydrophilic silica aerogel nanoparticles are remained (on the surface of MPSfunctionalized silica aerogel nanoparticles) and irreversible reaction between the growing radicals and these functional moieties can affect copolymerization rate and the conversion [54,55]. General procedure for preparation of random poly (styrene-co-butyl acrylate)/MPS-functionalized silica aerogel nanocomposites via in situ SR&NI ATRP SR&NI atom transfer radical random copolymerization of styrene and butyl acrylate in the… solution can be restricted by silica aerogel nanoparticles, especially at higher loadings.…”

Reverse atom transfer radical random copolymerization of styrene and methyl methacrylate in the presence of diatomite nanoplatelets

“…Nitroxide‐mediated polymerization, reversible addition‐fragmentation chain transfer polymerization, and atom transfer radical polymerization (ATRP) are 3 famous CRP methods in which have been extensively studied . Applicability to wide variety of monomers and polymerization systems, mild polymerization conditions, applicability of many metals as a mediator, and commercial availability of its reagents are some advantages of ATRP over other CRP methods …”

“…[19][20][21] Applicability to wide variety of monomers and polymerization systems, mild polymerization conditions, applicability of many metals as a mediator, and commercial availability of its reagents are some advantages of ATRP over other CRP methods. 19,22 A review of literatures indicates that application of diatomite as filler to synthesize polymer/diatomite composites have attracted considerable attention. Karaman et al have prepared polyethylene glycol/diatomite composite as a novel form-stable composite phase change material in which the phase change material was prepared by incorporating polyethylene glycol in the pores of diatomite.…”