Polymer-Coated Nanoparticles by Adsorption of Hydrophobically Modified Poly(N,N-dimethylacrylamide)

Abstract

We prepared a reactive random copolymer of N-acryloxysuccinimide and N,N-dimethylacrylamide (DMA) by reversible addition-fragmentation chain transfer polymerization, with Mn ≈ 50k and 23 mol % reactive NAS groups. This copolymer was subsequently modified with hydrophobic (dodecyl) and fluorescent (pyrene, PY; phenanthrene, PHE; or anthracene, AN) side groups, to obtain fluorescent amphiphilic polymers with the same backbone and different substituents. These polymers were adsorbed onto model (ca. 130 nm diameter) poly(butyl methacrylate) nanoparticles, and the size and structure of the adsorbed layer were evaluated using a combination of fluorescence techniques and light scattering. The total diameter increases very fast with polymer concentration up to ca. 140 nm, and then more slowly to 154 nm, stabilizing at this value which corresponds to a polymer shell thickness of ca. 12 nm. In order to evaluate the distribution of hydrophobic groups on the adsorbed polymer layer, we used Förster resonance energy transfer between PHE- and AN-labeled poly(DMA) chains. The obtained concentration profile of the adsorbed polymer corresponds to a coated particle radius which is only slightly smaller than the hydrodynamic radius measured in the same conditions, indicating that the dyes are not located at the particle interface but mostly distributed across the adsorbed layer. Finally, we observed that hydrophobically modified PHE-labeled poly(DMA) chains adsorbed to the nanoparticles were very efficiently displaced by identical hydrophobically modified chains with five times their molecular weight (Mn ≈ 250k) but labeled with PY.

Investigation of the Adsorption of Amphipathic macroRAFT Agents onto Montmorillonite Clay

“…Two types of cationic macroRAFT agents were prepared to interact with MMT: weak polyelectrolytes based on DMAEMA, which are positively charged when the amino groups are protonated (at pH 5, more than 95% of amino groups are supposed to be protonated), 47 and strong polyelectrolytes possessing quaternized DMAEMA units (qDMAEMA), which display permanent positive charges (independent of pH). Actually, very few studies have examined the interaction of DMAEMA-based (co)polymers with clay minerals.…”

“…Unlike the polycations reported in the literature, the DMAEMA-based macroRAFT agents synthesized in the present work have a relatively high percentage of hydrophobic units that can enable interchain contact in the adsorbed layer and may eventually lead to multilayer formation. 47 Thus, the continuous increase in the concentration of adsorbed macroRAFT agent may also be due to the formation of multilayers in addition to the conformation of the adsorbed chains mentioned above. The constants calculated by nonlinear regression for the BET model are displayed in Table S3 in Supporting Information (see Table S4 for the constants calculated for the other models).…”

Formation of polymer nanoparticles by UV pulsed laser ablation of poly (bisphenol A carbonate) in liquid environment

“…Polymer nanoparticles have found use in a number of applications like coating and functionalization of surfaces [5], adhesives [6], drug delivery systems [7], enhanced polymer blends preparations [8], organic photovoltaic systems [9] and smart/stimuliresponsive materials [10]. The applications of polymer nanoparticles are significantly affected by their physical properties as well as their surface morphology.…”

A FRET analysis of dye diffusion in core/shell polymer nanoparticles

“…8 In this work we have made use of the treatment developed by Martinho's group, 13,14 but slightly modi-ed, which has been applied successfully to determine the dye distribution in different systems with spherical symmetry. 11,15,16 The donor decay function aer a delta-pulse excitation is given by:…”