Neutron Scattering Studies of Structure and Self‐Assembly of Star‐Shaped Polymers with Fullerene Centres in Solutions

Abstract

Summary: Protonated star-shaped polystyrenes with single and double fullerene C 60 core and the hybrid stars with pairs of polar and non-polar arms (tertbuthylmetacrylate, polystyrene) have been studied in deuterated toluene (20 8C) by small-angle neutron scattering at low and moderate polymer concentrations (c 1 $ 1 g/dl, c 2 $ 3-6 g/dl) to evaluate the peculiarities of fullerene centre action on polymers selfassembly in solutions. As we found, the cores composed of two fullerenes, linked via Si(CH 3 ) 2 -bridge, induce stars' anisotropic interactions and association into chain-like structures (correlation radius $400-600 nm). Meanwhile, the single-core stars of polystyrene and hybrids organize globular clusters (size $ 10 3 nm) those geometry do not change significantly by polymer content variation.

Practical applications of small-angle neutron scattering

“…60 55,80 In these cases, SANS was employed for its ability to directly detect assembly structures in solution, with information from spectroscopy, microscopy or SAXS used to back up the analysis. In supramolecular chemistry, the ability to measure solution assembly structures is important as they often differ wildly from the solid-state assemblies of the same material and can provide the seeds from which they form.…”

“…62,67 2.2 Supramolecular self-assemblies SANS has also been used to characterise supramolecular assemblies, including self-assembling supramolecular polymers, 78 oligoelectroytes 79 and fullerene derivatives. 55,80 In these cases, SANS was employed for its ability to directly detect assembly structures in solution, with information from spectroscopy, microscopy or SAXS used to back up the analysis. In supramolecular chemistry, the ability to measure solution assembly structures is important as they often differ wildly from the solid-state assemblies of the same material and can provide the seeds from which they form.…”

Nanophase Separation-Induced Anomalous Enthalpy Hysteresis in Poly(n-alkyl methacrylate)s

“…This disappearance of the q III peak is consistent with the neutron scattering results showing that PtBMA does not experience nanophase separation. 70 Comparison of the results of Figure 6 with those of Figures 3 and 4 indicated that decreasing the size of phase-separated nanodomains seemed to diminish the deviation of the experimentally measured m and T g •ΔC p /ΔH R from theoretical eq 3. Once nanophase separation disappeared, such as PMMA and PtBMA, ΔH R recovered to a normal value as manifested by a slight deviation of the experimental data from eq 3 in Figures 3d and 4b.…”

“…This finding could be inferred from the changing trend of the q III peak in Figure a. This disappearance of the q III peak is consistent with the neutron scattering results showing that PtBMA does not experience nanophase separation …”