Dynamics of Polymers in Organosilicate Nanocomposites

Abstract

Dynamic secondary ion mass spectrometry (DSIMS) measurements were performed to measure the effects of functionlized organosilicate clay (Cloisite 6A) on the tracer diffusion coefficient, D, in polystyrene (PS) and poly(methyl methacrylate) (PMMA) matrices. The results indicate that D is unaffected by the addition of 5% (by volume) of PS and is reduced by a factor of 3 with the addition of the same volume fraction in a PMMA matrix. The same ratio was also obtained for the extrapolated zero shear rate viscosity of PS and PMMA melt-mixed composites with the same volume fraction of clay. DSIMS was also used to measure the mobility of the clay platelets, which was found to be much lower than the polymer chains in both matrices. Examination of the sample morphology with scanning force and transmission electron microscopy indicated that in contrast to melt mixing, spin casting produced a large degree of exfoliation in both PS and PMMA matrices. Hence the difference in the dynamics in the presence of clay was ascribed to preferential interactions between the PMMA polymer and the platelet surface, rather than the extent of exfoliation.

Characterization of Langmuir–Blodgett organoclay films using X-ray reflectivity and atomic force microscopy

“…This has several important implications on the interaction of the clay platelets when they are dispersed within a polymer blend. In contrast to expectations, that decreasing the surfactant coverage would allow the clays to disperse in polymers of varying polarity, we found that all clays, except the most polar (10A) were easily dispersed within slightly polar homopolymers, such as EVA and PMMA [22][23][24][25]. On the other hand, when highly immiscible blends were formed between polar and non-polar polymers, Si et al [10] reported that these clays were non-specific compatibilizers of a large class of blends.…”

Cluster secondary ion mass spectrometry of polymers and related materials

“…In addition, the sputter rate is significantly reduced when employing atomic beams, such that only dynamic SIMS instruments are typically used. There are several examples of polymeric depth profiling with atomic beams including PS (Whitlow & Wool, 1989, 1991Zhao et al, 1991;Shwarz et al, 1992;Liu et al, 1995;Zheng et al, 1995;Strzhemechny et al, 1997;Rysz et al, 1999;Yokoyama et al, 1999;Shin et al, 2001;Hu et al, 2003;Lin et al, 2003;Harton, Stevie, & Ade, 2006a,b,c;Harton et al, 2006d), PAMA (Valenty et al, 1984), PBMA (Verhoeven et al, 2004), PEVA (Verhoeven et al, 2004), PC (Valenty et al, 1984), PVDF (Chujo, 1991), PEO (Mattsson et al, 2000;Huang et al, 2001), PMMA (Chujo, 1991;Huang et al, 2001;Hu et al, 2003;Harton, Stevie, & Ade, 2006a,b,c;Harton et al, 2006d), polydimethyl phenylene oxide (PDPO) (Lin et al, 2003), PVP (Zheng et al, 1995;Pinto, Novak, & Nicholas, 1999;Yokoyama et al, 1999;Harton, Stevie, & Ade, 2006a,b;Harton et al, 2006d), PPV and other polymer based LED materials Bulle-Lieuwma & van de Weijer, 2006), solar cell materials (Bulle-Lieuwma et al, 2003), conducting polymers (Gray et al, 1992), video tapes (Chujo, 1991), silicones …”

Effects of carbon nanotubes on polymer physics

“…Studies with silica nanoparticles 33 found a monotonic decrease in diffusion constant with increasing filler concentration, another study with nanoclays found no change in diffusion coefficient at 5% clay content in polystyrene with a factor of three decrease in polymethyl methacrylate. 34 The results for carbon nanotubes are significantly more complicated. In two studies by Winey et al, 35,36 the authors found a minimum in diffusion constant with nanotube content in the case of single-walled and multiwalled nanotubes.…”