Metalated Diblock and Triblock Poly(ethylene oxide)-block-poly(4-vinylpyridine) Copolymers:  Understanding of Micelle and Bulk Structure

Abstract

The paper provides new insights into the structure of Pt-containing diblock and triblock copolymers based on poly(ethylene oxide) (PEO) and poly(4-vinylpyridine) (P4VP), using a combination of atomic force microscopy (AFM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and anomalous small-angle X-ray scattering (ASAXS). Parallel studies using methods contributing supplemental structural information allowed us to comprehensively characterize sophisticated polymer systems during metalation and to exclude possible ambiguity of the data interpretation of each of the methods. AFM and TEM make available the determination of sizes of the micelles and of the Pt-containing micelle cores, respectively, while a combination of XRD, TEM, and ASAXS reveals Pt-nanoparticle size distributions and locations along with the structural information about the polymer matrix. In addition, for the first time, ASAXS revealed the organization of Pt-nanoparticle-filled diblock and triblock copolymers in the bulk. The nanoparticle characteristics are mainly determined by the type of block copolymer system in which they are found: larger particles (2.0-3.0 nm) are formed in triblock copolymer micelles, while smaller ones (1.5-2.5 nm) are found in diblock copolymer micelles. This can be explained by facilitated intermicellar exchange in triblock copolymer systems. For both systems, Pt nanoparticles have narrow particle size distributions as a result of a strong interaction between the nanoparticle surface and the P4VP units inside the micelle cores. The pH of the medium mainly influences the particle location rather than the particle size. A structural model of Pt-nanoparticle clustering in the diblock PEO-b-P4VP and triblock P4VP-b-PEO-b-P4VP copolymers in the bulk was constructed ab initio from the ASAXS data. This model reveals that nearly spherical micellar cores of about 10 nm in diameter (filled with Pt nanoparticles) aggregate forming slightly oblate hollow bodies with an outer diameter of about 40 nm.

Structure and Properties of Iron Oxide Nanoparticles Encapsulated by Phospholipids with Poly(ethylene glycol) Tails

“…[33][34][35][36] SAXS provides size distributions of metal NPs, their locations in metalcontaining polymer matrixes, [37][38][39] and structural information about internal organization of the entire system. [40][41][42] In particular, ab initio methods for low-resolution model using SAXS data (e.g., program DAMMIN) 43 were successfully employed for metal-containing polymers. 41,44,45 In the present article, this and other novel methods for SAXS data analysis originally developed for biological systems are for the first time used to build structural models of iron oxide nanoparticles coated with PEGylated phospholipids.…”

“…[40][41][42] In particular, ab initio methods for low-resolution model using SAXS data (e.g., program DAMMIN) 43 were successfully employed for metal-containing polymers. 41,44,45 In the present article, this and other novel methods for SAXS data analysis originally developed for biological systems are for the first time used to build structural models of iron oxide nanoparticles coated with PEGylated phospholipids. Magnetic properties of the samples were also measured and support the conclusions from the SAXS modeling.…”

Environment-sensitive stabilisation of silver nanoparticles in aqueous solutions

“…Upon addition of AgNO 3 to the preformed C3Ms depicted in [6,20], silver ions are now selectively incorporated into the C3M cores as they contain pyridinium and acid groups. This results in the spontaneous (that is, without the addition of a reducing agent) formation of silver nanoparticles within the C3Ms, as manifested by a gradual yellowish/reddish coloration of the Ag-containing solutions in samples D and K (Fig.…”

“…Examples include Au-and Pt-NP formation in aqueous mixtures of P2VP-b-PEO and a wide variety of Au and Pt-NP precursors [6,20], comicellisation of c-Fe 2 O 3 and PTEA-bPAAm [13], and La(OH) 3 -NP formation in aqueous solutions containing La 3+ ions and PAA-b-PAAm copolymers [5,21,22]. Inspired by the spontaneous formation of silver nanowires in the presence of PMAA-b-PEO [4], i.e., without addition of a reducing agent, and the numerous studies on NP formation in the presence of P2VP and P4VP-containing copolymers (exhibiting a rather high affinity for many metal precursors due to the formation of coordination bonds between the metal ions and the pyridinium segments [6,7,23]), we decided to study Ag-NP formation in C3Ms consisting of poly(N-methyl-2-vinyl pyridinium iodide)-block-poly(ethylene oxide), P2MVP 38 -b-PEO 211 and poly(acrylic acid)-block-poly(isopropyl acrylamide), PAA 55 -b-PNIPAAm 88 .…”

Transport and Electro‐Optical Properties in Polymeric Self‐Assembled Systems

“…[358][359][360][361][362][363]). These and other deposition concepts can be applied to self-assembled structures to achieve conductivity [364].…”