Second and fourth generations of hydroxylated dendritic polyesters were combined with unmodified sodium montmorillonite clay (Na+MMT) in water to generate a broad range of amorphous polymer clay nanocomposite films from 0 to 100% wt/wt. Intercalation was the dominant state in these nanocomposites. Significant exfoliation was only observed within 0-5% wt/wt of mineral composition range. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to investigate intercalation states of the clay galleries. It was shown that interlayer spacing changed within the composition range 5-95% wt/wt from 0.5 nm to up to 3.5 nm in a step-like fashion with 0.5 nm increments which corresponded to a flattened conformation of confined HBPs. Second and fourth generations exhibited virtually the same layer-by-layer intercalation of completely flattened HBPs. No dependence of interlayer spacing on generation number was found. XRD and TEM revealed the presence of mixed intercalated populations with interlayer spacings at multiples of 0.5 nm. The existence of a long range segmental motion hindered (nanoconfined) fraction of a polymer (rigid amorphous fraction or RAF) was demonstrated and its amount quantified as well as the amount of regular (mobile amorphous fraction MAF) over a broad range of clay loadings via measurements of heat capacity at the glass transition of the nanocomposites. The existence of RAF was also demonstrated and its amount quantified by positron annihilation lifetime spectroscopy (PALS). Both methods showed an excellent agreement.

Probing rigid amorphous fraction in intercalated clay nanocomposites prepared from water soluble hyperbranched polyesters

247th National Meeting (2014)

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