Nanocapsules composed of a poly(vinylferrocene)-block-poly(methyl methacrylate) shell and a hydrophobic liquid core are prepared in water. The nanocapsule shells display a patchy structure with poly(vinylferrocene) patches with sizes of 25 ± 3 nm surrounded by poly(methyl methacrylate). The functional nanopatches can be selectively oxidized, thereby influencing the colloidal morphology and introducing polar domains in the nanocapsule shell. The hydrophobic to hydrophilic transition in the redox-responsive nanopatches can be advantageously used to release a hydrophobic payload encapsulated in the core by an oxidation reaction.

Well-defined poly(2-(methacryloyloxy)ethyl ferrocenecarboxylate) (PFcMA) brushes were synthesized by surface-initiated atom transfer radical polymerization (SI-ATRP) on cross-linked polystyrene particles. The ATRP of FcMA monomer was reinvestigated leading to molar masses up to 130 kg mol–1 with a good reaction control and high monomer conversion (91%). The SI-ATRP was done with different amounts of initiator in the PS particle shell leading to PFcMA surface conformations from “mushroom-like” to dense “brush-like” polymers, which could be confirmed by dynamic light scattering (DLS) experiments. Redox-responsive behavior of the PFcMA shell was investigated by DLS and cyclic voltammetry (CV) measurements indicating a tremendous increase in the hydrodynamic volume of the ferrocene-containing shell. The transformation of PFcMA-grafted PS particles to magnetic iron oxides after thermal treatment could be investigated by SQUID magnetization measurements showing the typical hysteresis for ferromagnetic material.

We describe the synthesis of water-soluble diblock and miktoarm star polymers consisting of poly(vinylferrocene) (PVFc) and poly(ethylene oxide) (PEO) blocks. First, end-functionalized poly(vinylferrocene) was generated by end-capping the living carbanionic PVFc chains with benzyl glycidyl ether (BGE) or ethoxy ethyl glycidyl ether (EEGE). Acidic hydrolysis of the EEGE-terminated PVFc partially oxidized the PVFc backbone. However, the dihydroxyl end-functional PVFc was obtained in quantitative yields by hydrogenolysis of the BGE-terminated PVFc. A series of block copolymers and AB2 miktoarm star copolymers was obtained in a second polymerization step, utilizing the respective end-functionalized PVFc as a macroinitiator for the ring-opening polymerization (ROP) of ethylene oxide. All polymers were analyzed in detail, using NMR spectroscopy and size-exclusion chromatography (SEC). Online SEC-viscosimetry as well as MALLS was carried out, confirming the formation of miktoarm structures. Quantitative functionalization and subsequent removal of the acetal and benzyl protective groups, respectively were confirmed by MALDI–ToF mass spectrometry. Molecular weights of the end-functionalized PVFcs range between 1000 and 3600 g mol–1, and block copolymers with 10 000 to 50 000 g mol–1 overall molar masses were synthesized. In addition, the water-soluble block copolymers were investigated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). For characterization of the morphology in aqueous solution, transmission electron microscopy (TEM) was performed, showing micelles and multicompartment micellar structures.

No abstract

The synthesis of polystyrene (PS) brushes on fully deuterated PS nanoparticles by surface-initiated nitroxide-mediated radical polymerization (SI-NMRP) is reported. Due to the high demand of deuterated monomers, an effi cient deuteration procedure of suitable and readily available precursors is developed. SI-NMRP of styrene is improved regarding reaction control, grafting density, and conversion. Insights into the scaling behavior and conformational features of surface-attached PS chains on deuterated particles are investigated by using dynamic light scattering measurements, proving that polymer brushes are formed. The particles with surface-attached initiator are shown to be uniform spherical core-shell particles by small-angle neutron scattering measurements.

Abstract:In the present study, the synthesis of poly(1,1-dimethylsilacyclobutane) (PDMSB) by anionic ring opening polymerization (ROP) is reinvestigated, leading to narrowly distributed molar masses (polydispersities 1.04-1.15) in the range of 2.3 to 60 kg mol −1. Investigations of thermal behavior for low molar mass PDMSB revealed an untypical multiple peaks melting phenomenon, which at first glance, seems to be of the same origin as low molar mass poly(ethylene oxide)s. Small angle X-ray scattering (SAXS) and X-ray diffraction (XRD) measurements are done, proving the fast crystallization and subsequent recrystallization for investigated low molar mass samples. Synthetic attempts are expanded to the surface-initiated anionic ROP of 1,1-dimethylsilacyclobutane (DMSB) monomer from the surface of cross-linked polystyrene (PS) nanoparticles. Novel polycarbosilanes (PCS)/organic core/shell particles are obtained, which are investigated by using transmission electron microscopy (TEM) and dynamic light scattering (DLS) experiments. First insights into the crystallization behavior OPEN ACCESSPolymers 2013, 5 285 of surface-attached PDMSB chains reveal that crystallization seems to be hindered.

SUPPORTING INFORMATION EXPERIMENTAL SECTIONReagents. All chemicals and solvents were purchased from Fisher Scientific, Sigma-Aldrich and Alfa Aesar and used as received if not otherwise mentioned. Styrene and divynylbenzene (DVB) were passed through a column filled with basic alumina. Cu(I)Br and Cu(I)Cl were washed five times with glacial acetic acid and ethanol and dried in vacuo. N-,N-,N'-,N'-,N''-Pentamethyldiethylenetriamine (PMDETA), anisole, 2-bromo-iso-butyric tert-butylester (tBbiB), hydroxyethylmethacrylate (HEMA), and α-bromoisobutyryl bromide were degassed and stored under an argon atmosphere or in gloveboxes.All ATRP were conducted under nitrogen or argon atmosphere. The copper complexes were freshly prepared in anisole and stored in the glovebox. The ATRP-inimer 2-(2-Bromoisobutyryloxy)ethyl methacrylate 1 was synthesized described elsewhere. 49 Bis(thiobenzoyl) disulfide (BTBD) 2 was easily obtained following the reaction sequence described by Sanderson et al.. 50

We previously reported that grafted polystyrene (PS) chains on silica nanoparticles at a low grafting density show similar conformations to free PS chains in the same solvent, THF (diameter ∼50 nm, Colloid.poly.Sci. (2013), 291, 9, 2087-2099. As an extension of our previous study we choose an organic nanoparticle (deuterated polystyrene, dPS) instead of inorganic nanoparticle to see the impact of the substrate material on chain conformation. Additionally, a wider range of molecular weights were prepared to investigate the conformation feature of grafted PS chains more in detail. Small angle neutron scattering (SANS) experiments were performed to characterize PS grafted dPS particles in good solvent condition, with deuterated toluene and deuterated THF as solvent. To get insight into the conformation of the grafted PS layer we apply a scaling law describing the dimension of free PS polymer in good solvent condition to the obtained thickness of the grafted PS layer. We find an overall agreement with the scaling law where the thickness of the grafted PS layer is slightly larger than 2R g of the free polymer chains in the respective solvent giving hint for semi dilute polymer brush (SDPB) situation.