Formation of Reactive Polymer Nanoparticles

With the discovery of the FRRPP of methacrylic acid (MAA) in water at temperatures below the boiling point of the mixture, it has become possible to carry out in situ polymerization experiments in glass and quartz containers. Small-angle X-ray scattering (SAXS) experiments using the synchrotron X-ray source of the MAA/water reactive system (Fig. 2.1.1) showed persistence of Gaussian coil nanoscale domains (Tirumala et al., 2003a,b,c). 

Comparing radii of gyration with conversion data, the relatively high conversion at 60°C and lower molecular sizes mean that more of the polymer settled to the bottom of the vessel. The opposite was observed for conversion and molecular size data at 80°C. Even the prereacted sample resulted in progressively lowering 

Methacrylic acid/water system, reacting 80° C 11 nm 13 nm (17%) 12nm(32%) 

Methacrylic acid/water system, prereacted for 15 min 60° C and continued reacting 80°C 13 nm 10 nm 10 nm 

Subsequently, a more direct verification of formation of persistent nanoscale domains was done by running the FRRPP of MAA/water in a quiescent fluid, and then doing a morphological analysis of the product polymer material from liquid samples that were frozen to preserve the polymer structure from the liquid before drying. The result is a picture from the atomic force micrograph (AFM) of nanoparticles from a polystyrene/ether reactive FRRPP system, shown in Fig. 2.1.2. 

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