Dependence of the structure of core–shell–corona micelles on the composition of water/toluene mixtures

Abstract

The poly(styrene)-block-poly(2-vinylpyridine)-block-poly(ethylene oxide) triblock copolymer, PS , where the subscripts refer to the average degrees of polymerisation of the constitutive blocks, has been dissolved in water/toluene mixtures with a large range of composition, i.e. in (i) toluene added with a small amount of water, (ii) water-in-toluene emulsion forming mixtures, (iii) toluene-in-water emulsion forming mixtures, and (iv) water added with a small amount of toluene. These solutions have been cast on a carboncoated copper grid, and the morphology of the dried copolymer deposition has been observed by transmission electron microscopy. Rod-like aggregates with a core-shell-corona micellar structure are formed in cases (i) and (iv). Nevertheless, PEO is the core and PS is the corona in case (i), whereas the reverse situation prevails in case (iv). When an emulsion is the precursor of the dried copolymer aggregates, either onion-like structures (case ii) or vesicles mixed with more complex aggregates are formed (case iii). These structures are thought to reflect the self-organization of the PS 200 _ b-P2VP 140 -b-PEO 590 copolymer at the water/toluene interface of the water-intoluene and toluene-in-water emulsions, respectively.

Preparation and control of functional nano-objects: Spheres, rods and rings based on hybrid materials

“…As reported before, the water content is the main determinant of the morphology of copolymeric systems in aqueous solvent blends [48]. The crucial parameter is the amount of water that effectively swells the P4VP block.…”

“…In fact, the spherical morphologies, observed in wateretoluene mixtures, are micelles with a swollen core; their diameter is 50 nm compared to 42 nm in pure toluene. If the swelling reaches a certain limit (according to n H 2 O =n 4VP > 1), the system reassembles into rod-and ringlike structures rather than only spherical morphologies to maintain the force equilibrium [29]. The diameter of the rod-and ring-like aggregates is slightly smaller (z45 nm) than those of the spherical micelles.…”

“…The copolymer was dissolved directly in watere toluene mixtures to obtain contents of 0.5% of copolymer; gold precursor was added in stoichiometric amounts with respect to the number of pyridine units (each pyridine unit forms a complex with the gold precursor, 4VP:HAuCl 4 ¼ 1:1). After stirring for 48 h, a milky suspension is obtained, indicating a typical water-in-toluene emulsion [29].…”

Nanoparticle carriers based on copolymers of poly(ε-caprolactone) and hyperbranched polymers for drug delivery

“…1 H NMR and 13 C NMR spectra of HPAE-OHs were dissolved in DMSO-d6. HPAE-co-PCL copolymers were dissolved in CDCl 3 .…”

“…Polymeric micelles from amphiphilic block copolymers [1,2] are supramolecular core-shell-type assemblies of tens of nanometers in diameter, which can mimic naturally occurring biological transport systems such as lipoproteins and viruses [3]. Recently, polymeric micelles as carriers of anti-tumor drugs have drawn increasing research interests, due to their various advantages in drug delivery applications.…”