Thermal behaviour of TiO₂‐encapsulating polymers

Abstract

Comparing the thermal properties of TiO, encapsulating polystyrene and poly(methy1 methacrylate) with those of TiO, dispersion polymers it was found that the encapsulating polymers have two thermal relaxation regions. The activation energy of those thermal relaxation regions was determined using the Wunderlich method and it was found that the values are similar to the activation energy for the dynamic dispersion. It is suggested that the low-temperature thermal relaxation is caused by the local change of conformation of molecular chains, while the high-temperature thermal relaxation is similar to that of the normal glass transition temperature including the interaction with TiO,. In addition, the thermal behaviour near the degradation point in different atmospheres indicates that the encapsulating polymer has a specific structure for adsorbing a large amount of oxygen. ZUSAMMENFASSUNGDie thermischen Eigenschaften von Polystyrol and Poly(methylmethacry1at) mit verkapseltem und dispergiertem TiO, wurden verglichen. Die verkapselnden Polymeren zeigen zwei thermische Relaxationsbereiche, deren nach Wunderlich ermittelte Aktivierungsenergien denen von dynamischen Dispersionen ahnlich sind. Es wird vorgeschlagen, da8 die Niedertemperaturrelaxation durch lokale hderungen der Konformation der Makromolekule hervorgerufen wird, wahrend die Hochtemperaturrelaxation dem normalen Glasubergang einschlieBlich der Wechselwirkung mit TiO, vergleichbar ist. Das thermische Verhalten nahe der Zersetzungstemperatur in verschiedenen Atmosphiiren deutet darauf hin, da8 in den verkapselnden Polymeren spezifische Strukturen vorhanden sind, die eine groBe Menge Sauerstoff adsorbieren konnen.

Photovoltaic Properties of Polymer/Fe2O3/Polymer Heterostructured Microspheres

“…Polymer materials maybe a good substance for passivation, since they have large band gaps and low conductivity due to the small number of charge carriers with very low mobility and the high trap density. In the past, many inorganic particles were encapsulated in the polymer layer in order to affect the physical properties of such powders, particularly in terms of increasing their dispersity in solvents or in composite phases. − Only Y. Haga et al found that the photoconductivity of CdS, ZnO, and TiO 2 was affected by the interaction between the polymers and the inorganic phases and the effect upon the electron transport process was thought to be especially large. − In this paper, Fe 2 O 3 nanoparticles with diameters of 3−5 nm were encapsulated in the polymer microspheres in a trilayer core−shell heterostructure. The effect of polymers on its properties were investigated by UV spectroscopy and surface-photovoltage spectroscopy.…”

Encapsulation of titanium dioxide in styrene/n‐butyl acrylate copolymer by miniemulsion polymerization

“…The encapsulation of inorganic particles of submicron size has been investigated using a number of different polymerization methods, including emulsion polymerization,7–22 interfacial polymerization,23–25 suspension polymerization,26–28 and more recently, miniemulsion polymerization 29. Inorganic particles have included TiO 2 , carbon black, magnetite, quartz powder, SiO 2 , CdS, BaSO 4 , and CaCO 3 , while polymers have included polystyrene, poly(vinyl acetate), poly(butyl acrylate), and poly(methyl methacrylate).…”

“…Inorganic particles have included TiO 2 , carbon black, magnetite, quartz powder, SiO 2 , CdS, BaSO 4 , and CaCO 3 , while polymers have included polystyrene, poly(vinyl acetate), poly(butyl acrylate), and poly(methyl methacrylate). Both conventional and emulsifier‐free emulsion polymerizations13–22 have been carried out. The major obstacles in successfully applying emulsion polymerization as an encapsulation method are attributed to the complexity of the particle nucleation mechanism (micellar, homogeneous) and the difficulties in controlling the dispersion stability of the inorganic particles in the aqueous phase prior to and during polymerization.…”

Particle size and morphology of poly[styrene‐co‐(butyl acrylate)]/nano‐silica composite latex

“…Polymers encapsulating nano‐sized inorganic particles such as TiO 2 , CaCO 3 , Fe 3 O 4 and SiO 2 show improved thermal, mechanical, optical and other properties due to the combined properties of inorganic nanoparticles and organic polymers, and they can be widely used in plastics, rubbers, cosmetics, inks, coatings, etc 1–7…”