Supercritical Carbon Dioxide-Processed Dispersed Polystyrene−Clay Nanocomposites

Abstract

Achieving clay dispersion and improving clay−polymer interactions are keys to producing superior nanocomposites. A supercritical CO2 (scCO2) processing method was utilized to prepare high molecular weight polystyrene (PS)/Cloisite 10A nanocomposites with significant dispersion and rheological enhancement. The effects of scCO2 processing, presence of cosolvent, and clay weight fraction on clay dispersion and polymer−clay interactions in nanocomposites were investigated. Rheology, WAXD, and TEM of the nanocomposites indicate that substantial improvements in the rheological properties of scCO2 nanocomposites are the result of increased dispersion and polymer−clay interactions. At low frequencies, the elastic plateau modulus of the scCO2-processing nanocomposites (5 wt % clay loading) is more than 40-fold higher than benchmark solution-blended samples. Our results suggest that the substantial contacting with scCO2, followed by rapid depressurization, produces a combination of disorder and dispersion of this “as-received” clay, and the presence of the cosolvent enables more intimate contact of the high molecular weight PS and clay.

Nanocomposite organomineral hybrid materials. Part 3

“…Addition of them to the polymer, even small amounts of Silicate nanoplates (usually 3-5 wt.%), can significantly improve the barrier diffusing material properties, thermal stability, resistance to thermal warping [168][169][170][171][172]. This is due to the fact that in contrast to conventional composites (single components of conventional composites have micron and submicron sizes) to nanomaterials characterized extremely high interfacial area boundaries, resulting in their role in the formation of physical properties of the material becomes dominant.…”

“…These particles can be chaotically distributed in the volume of material or can form individual packs -tactoids. Tactoids consist of several (usually on the order of tens) of parallel plates, between which one or more molecules of the polymer matrix [172] are located. In the first case the nanocomposites are called exfoliated materials, in the second -intercalated materials.…”

Influence of physical state of intercalating agents on intercalation process of high speed airflow pretreated montmorillonite in supercritical carbon dioxide

“…Besides, the CO 2 can be removed entirely from the product without bringing pollution. These unique properties of scCO 2 have yet been exploited for intercalating and exfoliating layered silicates [8][9][10]. Serhatkulu et al [8] used supercritical CO 2 as the processing medium for intercalating the structure of natural clay and depositing CO 2 -philic sugar acetate.…”

Role of water on PMMA/clay nanocomposites synthesized by in situ polymerization in ethanol and supercritical carbon dioxide

“…In their work, they compared the effects of PDMS-clay on the morphologies and properties of PMMA and PS nanocomposites. Recently, Manitiu et al investigated the effect of scCO 2 processing in clay dispersion, polymer-clay interaction and the thermal degradation of polymer nanocomposites [24]. The liquid-like density and gas-like diffusivity of scCO 2 allow it to penetrate the platelet galleries during a soaking period, while the large density change that the supercritical fluid undergoes during instantaneous depressurization pushes the platelets apart.…”