Core@shell Poly(n -butylacrylate)@polystyrene Nanoparticles: Baroplastic Force-Responsiveness in Presence of Strong Phase Separation

Abstract

Poly(n-butylacrylate)@polystyrene nanoparticles behaving as a capsule-based sealing nanoadditive are synthesized through an optimized semicontinuous emulsion polymerization protocol. Solid state time-domain (1)H-NMR and (13)C magic angle spinning (MAS) NMR analysis suggest strong phase separation. Line width of (13)C resonances in cross polarization and single pulse experiment MAS-NMR spectra indicates that the peculiar mobility of each phase is preserved at the nanoscale. Atomic force spectroscopy (AFM) shows the permanence of spherical shape in absence of solvent (i.e., subsequent to strong capillary and surface forces) up to moderate external load, as well as the possibility of plastically deforming the polystyrene shell and ultimately triggering the nanoparticle flow at higher force loads. The breakdown characteristic of the nanoparticle shows for the first time baroplastic behavior on a single particle with precise biphasic core@shell morphology.

Unraveling Triplet Excitons Photophysics in Hyper-Cross-Linked Polymeric Nanoparticles: Toward the Next Generation of Solid-State Upconverting Materials

“…Notably, the steady-state PL data suggest that the triplet diffusion length L in the NPs is comparable to that of dyes in solution and significantly larger than that in bulk PS. To get deeper insight into the mechanism controlling the excitonic diffusion in NPs, we performed a detailed study of their structure, combining differential scanning calorimetry (DSC), time domain NMR data, and porosity measurements. − The NPs have a hyper-cross-linked structure that is more rigid than bulk PS, as demonstrated by the absence of any glass transition phase change up to more than 470 K and by the lack of viscous subdomains (Figures S2 and S3). The porosity of undoped NPs was probed by 129 Xe NMR spectroscopy, which measures the chemical shifts of the gas as a function of the pore size (Figure a).…”

Viscosity Modification of Polymerizable Bicontinuous Microemulsion by Controlled Radical Polymerization for Membrane Coating Applications

“…The HPDEC spectra were recorded with 20 s of recycle delay. Amorphous polymers with a low glass transition temperature, in general, can be analyzed more quantitatively with this technique [29]. This was also confirmed by the nearly constant 1:3 ratio between the methyl groups and the non-direct bonding to nitrogen or oxygen methylenes of the polymerized AUTEAB molecules (8.5 and 22-29 ppm, respectively) for all samples.…”

Time Domain NMR in Polymer Science: From the Laboratory to the Industry

“…Temperature dependence of PBA@PS core-shell nanoparticles rigid fraction. The inset highlights the region close to room temperature, showing an agreement of the composition with the expected composition derived from the synthesis feed, indicated by the solid line (Reprinted with permission from reference[51]. Copyright 2016 Wiley).…”

“…Monitoring the reduction of rigid fraction from below the PBA Tg towards higher temperatures, two softening regions were detected, as shown in Figure 9: the first one corresponding to the complete mobilization of PBA protons above Tg, a second one at higher temperature than PS Tg, where the system starts to reptate and no rigid fraction remains. In between these two transitions only PS protons contribute to rigid fraction [51]. Furthermore, common plastics can acquire a plethora of new perspectives, depending on chemical modification or manufacturing.…”