Self-Assembly of Maltoheptaose- block -Polystyrene into Micellar Nanoparticles and Encapsulation of Gold Nanoparticles

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Thermoresponsive Vesicular Morphologies Obtained by Self-Assemblies of Hybrid Oligosaccharide- block -poly( N -isopropylacrylamide) Copolymer Systems

International audienceThis work discusses the self-assembly properties of thermoresponsive hybrid oligosaccharide-block-poly(N-isopropylacrylamide) copolymer systems: maltoheptase-block-poly(N-isopropylacrylamide) (Mal(7)-b-PNIPAM(n)) copolymers. Those systems at different molar masses and volume fractions were synthesized Using Cu(I)-catalyzed 1,3-dipolar azide/alkyne cycloaddition, so-called "click" chemistry, between an alkynyl-functionalized maltoheptaose (I) and poly(N-isopropylacrylamide) having a terminal azido group (N(3)-PNIPAM(n)) prepared by atom transfer radical polymerization (ATRP). While the cloud point (T(cp)) of the N(3)-PNIPAM(n) ranged from 36.4 to 51.5 degrees C depending on the degree of polymerization, those obtained of the diblock copolymers ranged from 39.4 to 73.9 degrees C. The self-assembly of such systems is favored due to the hydrophobicity of the PNIPAM in water above the T(cp). While the N(3)-PNIPAM(n) present polydisperse globular shape with a mean diameter of 500 nm, well-defined vesicular morphologies with an approximate diameter of 300 nm are obtained in diblock copolymer systems. These results were obtained and confirmed using static and dynamic light scattering as well as imaging techniques such as transmission electron microscope experiments

Polymeric Vesicles and Micelles by Self-assembly of Ionic Liquid-based Block Copolymers Triggered by Anion or Solvent Exchange

The solution properties of IL-based block copolymers (IL BCs) of the type PAm-b-PIL-1Br, PMAA-b-PIL-2Br and PMAA-b-PIL-3Br, where PIL, PAm and PMAA stand for polymeric ionic liquid, polyacrylamide and poly(methacrylic acid), respectively, are manipulated and made to self-assemble into nanoparticles in water or in organic media. This can be achieved not only by simply exchanging the bromide (Br-) counter-anion of IL blocks for - N(SO2CF3)2 , but also by the choice of a selective solvent or by methylation of the hydrophilic PMAA blocks into hydrophobic poly(methyl methacrylate) (PMMA) ones. Investigations into the behaviour of self-assembled IL BCs aggregates by 1H NMR spectroscopy, light scattering and transmission electron microscopy evidence that anion or solvent exchange or chemical modification induce the formation of polymeric vesicles referred to as polymersomes, for IL BCs of hydrophilic mass fraction (f) of around 40. The size and shape of the self-assembled aggregates formed can be altered by changing the composition of the blocks or by a partial exchange of the anion. In addition, the anion-sensitivity of these IL BCs occurs reversibly. For instance, anion exchange of the PIL block, from Br- to -N(SO2CF3)2 leads to a vesicular morphology consisting of -N(SO2CF3)2-based IL blocks as the hydrophobic membrane stabilized by water-soluble PAm (or PMAA). As for PAm135-b-(PIL-1N(SO2CF3)2)12 IL BC possessing a hydrophilic mass fraction higher than 45, it is found to self-assemble into spherical polymeric micelles