Dynamics of Soft and Hairy Polymer Nanoparticles in a Suspension by NMR Relaxation

Abstract

The design of surface-modified functional nanoparticles (NPs) is used to control the properties of the NPs and the NP/environment interactions. The efficient control of the final behavior of the NPs demands a comprehensive understanding of the resulting system. This is particularly challenging for systems with an architecture of the type polymer core− polymer canopy. In such systems, one of the key parameters influencing the behavior of the NPs is the local dynamics of the polymer canopy. However, because the grafting points of the canopy are experiencing their own local dynamics, predicting the final behavior of such systems is difficult. To get a deeper understanding of NPs made of a soft and swollen polymer core and a swollen polymer canopy, we prepared a library of hairy NPs made of a polystyrene (PS) core and a canopy of grafted poly(methyl acrylate) (PMA) chains. The softness of the PS core and the thickness of the PMA canopy were controlled, and the behavior and dynamics of the soft and hairy PS−PMA NPs in suspension were measured by 1 H NMR relaxation and dynamic light scattering. It was observed that the rigid PS core slowed down the subsegmental dynamics of the PMA chains, while thick PMA canopies accelerated the relaxation of the PS core. The dynamics of the NPs in suspension was the result of the interplay between the PS core and the PMA canopy.

Influence of the Architecture of Soft Polymer-Functionalized Polymer Nanoparticles on Their Dynamics in Suspension

“…However, in the case of the PS core, the τc increased with an increase in the temperature (Figure 3c,d). This unexpected result is related to the deswelling of crosslinked PS observed at high temperatures in specific solvent systems ( Figure S6, Supplementary Material) [12,42]. The energy of activation of the PMA chains of PS-PMA core-canopy NPs was calculated using the τc measured at different temperatures (Figure 4a).…”

“…However, in the case of the PS core, the τ c increased with an increase in the temperature ( Figure 3 c,d). This unexpected result is related to the deswelling of crosslinked PS observed at high temperatures in specific solvent systems ( Figure S6 Supplementary Material , ) [ 12 , 42 ].…”

“…Variations in N and σ in systems where the polymer chains are tethered to hard and rigid nanoparticle core, such as silica or gold, influence the dynamics of the grafted polymer chains.And the architecture of the canopy of grafted polymer chains defines the interfacial properties of the NPs, such as particle/particles interaction or NPs/solvent interaction [6][7][8][9][10][11]. However, the behavior of systems where the core is itself soft and deformable like a nanogel has not been addressed, and the dynamics of polymer chains grafted on the surface of soft NPs need to be thoroughly understood to improve the design of such systems [12].…”

Polymer Adsorbents vs. Functionalized Oxides and Carbons: Particulate Morphology and Textural and SurfaceCharacteristics

“…The latter may be characterized by lower stability of the textural characteristics than stable and rigid solids due to various effects of dispersion media, swelling, aging, freezing with liquids, heating, mechanical loading, as well as due to high fractality, strongly tortuous pores, and disordered texture of nonrigid polymers [26][27][28][29][30][31][32][33][34]. Various composites [35][36][37][38], nanostructured polymers [39][40][41][42][43][44][45], polymer/oxides [46][47][48], and polymer/carbons [49][50][51][52] composites are of interest from a practical point of view. However, accurate textural characterization of polymeric composites, complex filler-polymer and filler-polymer-polymer systems is a more difficult task than a similar challenge for individual oxide, carbon, or polymeric materials.…”

Impact of the Solvent Quality on the Local Dynamics of Soft and Swollen Polymer Nanoparticles Functionalized with Polymer Chains

“…The contribution of the solvent quality on the swelling and dynamics of both the core and the end-tethered layers needs to be studied in more detail. The interplay between the dynamics of the shell and of the core NP needs to be better understood. , Here, to understand the effect of solvent quality on the dynamics of swollen polymer NPs functionalized with a canopy of polymer chains, we functionalized cross-linked polystyrene (PS) NPs with a canopy of poly­(methyl acrylate) (PMA). PS and PMA are two immiscible polymers that can be selectively solvated using binary mixtures of solvent (Figure ).…”