Polydimethylsiloxane-Based Diblock Copolymer Nano-objects Prepared in Nonpolar Media via RAFT-Mediated Polymerization-Induced Self-Assembly

Abstract

and relatively low final polydispersities (M w /M n = 1.14 -1.34). Small-angle X-ray scattering (SAXS) has been used to characterize selected examples of the spherical nanoparticles in order to obtain volume-average diameters, which increase monotonically when targeting longer DPs for the coreforming PBzMA block. A relatively high copolymer concentration (> 25 % w/v) is required to obtain a pure worm phase, which occupies an extremely narrow region within the phase diagram. Selected worm and vesicle dispersions were also analyzed by SAXS, which enables determination of the mean worm cross-section, mean worm length and vesicle membrane thickness, respectively. In addition, the highly anisotropic worms formed free-standing gels in n-heptane, with rheology measurements indicating viscoelastic behavior and a gel storage modulus of around 10 4 Pa.

Polymerization-induced self-assembly of block copolymer nanoparticles via RAFT non-aqueous dispersion polymerization

“…These formulations were later extended by Pei et al by introducing pentafluorophenyl methacrylate (PFPMA) residues into the PSMA macro-CTA to enable post-polymerization modification of this stabilizer block via nucleophilic acyl substitution [99]. A further RAFT dispersion polymerization formulation in non-polar media was recently reported by Lopez-Oliva et al [103]. A near-monodisperse monocarbinol-functionalized polydimethylsiloxane (PDMS) was esterified using PETTC, with the resulting macro-CTA being subsequently used for the RAFT dispersion polymerization of BzMA in n-heptane at 70 °C (Figure 14a).…”

“…In principle, preparing non-vinyl macro-CTAs such as PDMS-PETTC via end-group modification of an existing commercial precursor should provide reproducible access to the same mean stabilizer DP. This is expected to be useful for the construction of phase diagrams, for which remarkably narrow region was observed for the pure worm phase (Figure 14c) [103]. …”

Self-assembly of thermo and light responsive amphiphilic linear dendritic block copolymers

“…In a first approach, this type of scattering is compatible with the presence of the vesicle observed by TEM. [17] [18] Due to the limited q range of the experiment, the scattering curve could not be fitted properly. However, based on TEM, a globular shape of the scattering objects can be considered and, therefore, SAXS profiles can be analyzed by using the Guinier approach for globular objects.…”

A Critical Appraisal of RAFT-Mediated Polymerization-Induced Self-Assembly

“…75,76 In addition to spheres, worms, and vesicles, 33,34,36,37,55,60,61,65,69,77−85 other unusual morphologies have also been produced by PISA, such as lamellae, 72 framboidal vesicles, 86 spaced concentric vesicles, 74 and yolk/shell particles. 62 Examples of these morphologies are shown in Figure 1.…”