Recent appointees in Polymer Science special issue

Recent appointees in Polymer Science special issu

The direct synthesis of sulfobetaine-containing amphiphilic block copolymers and their self-assembly behavior

Diblock copolymers containing the thermo-responsive sulfobetaine, [2-(methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide (DMAPS), were synthesized by the aqueous RAFT polymerization of DMAPS, followed by direct chain extension in hexafluoroisopropanol (HFIP) with methyl methacrylate (MMA). This was shown to give lower dispersity polymers than RAFT emulsion polymerization. The diblock copolymers self-assembled in water to form micelles, as analyzed by light scattering (LS) and transmission electron microscopy (TEM). Micelles formed from diblocks bearing a long PDMAPS block were shown to swell with temperature, rather than display a traditional UCST cloud point. This was due to the polymers retaining hydrophilicity, even at temperatures well below the UCST for the corresponding PDMAPS homopolymer, as shown by variable temperature NMR. This swelling behavior was utilized in the release of a hydrophobic dye in response to temperature. This approach has great potential for applications in controlled release whilst maintaining the structure of the carrier nanoparticles

Mixing in microfluidic devices as a new strategy for fabrication of nanoparticles

Mixing in microfluidic devices as a new strategy for fabrication of nanoparticle

Production of biocompatible gold nanoparticles for drug delivery using droplet based glass capillary microfluidic [Abstract]

Production of biocompatible gold nanoparticles for drug delivery using droplet based glass capillary microfluidic [Abstract

Bioinspired poly(vinylidene fluoride) membranes with directional release of therapeutic essential oils

Here, the morphology of polypore fungi has inspired the fabrication of poly(vinylidene fluoride) (PVDF) membranes with dual porosity by nonsolvent-induced phase separation (NIPS). The fruiting body of such microorganisms is constituted of two distinct regions, finger- and sponge-like structures, which have been successfully mimicked by controlling the coagulation bath temperature during the NIPS process. The use of water at 10 °C as coagulant resulted in membranes with the highest finger-like/sponge-like ratio (53% of the total membrane thickness), while water at 90 °C allowed the formation of macrovoid-free membranes. The microchannels and the asymmetric porosity were used to enhance the oil sorption capacity of the PVDF membranes and to achieve directional release of therapeutic essential oils. These PVDF membranes with easily tuned asymmetric channel-like porosity and controlled pore size are ideal candidates for drug delivery applications

One-pot synthesis of responsive sulfobetaine nanoparticles by RAFT polymerisation: the effect of branching on the UCST cloud point

We describe the one-pot synthesis of temperature-responsive branched polymer nanoparticles. Reversible addition–fragmentation chain transfer (RAFT) polymerisation has been utilised to synthesise ultra-high molecular weight sulfobetaine polymers (up to ca. 500 kDa) with good control over molecular weight (Mn) and dispersity (Mw/Mn). The UCST cloud points of these linear polymers were found to increase with both Mn and concentration, and represent one of the few recent descriptions of polymers exhibiting UCST behaviour in aqueous solution. The incorporation of difunctional monomers results in branched polymers which display vastly reduced transition temperatures compared to their linear counterparts. Furthermore, the incorporation of a permanently hydrophilic monomer results in the formation of stable core–shell particles which no longer exhibit a cloud point in water, even at very high concentrations (ca. 50 mg mL−1). The branched polymers are shown to form discrete well-defined nanoparticles in aqueous solution, and these have been characterised by DLS, SLS, TEM and DOSY. Their reversible swelling behaviour in response to temperature is also demonstrated

Efficient access to conjugated 4,4′-bipyridinium oligomers using the Zincke reaction: Synthesis, spectroscopic and electrochemical properties

The cyclocondensation reaction between rigid, electron-rich aromatic diamines and 1,1′-bis(2,4-dinitrophenyl)-4,4′-bipyridinium (Zincke) salts has been harnessed to produce a series of conjugated oligomers containing up to twelve aromatic/heterocyclic residues. These oligomers exhibit discrete, multiple redox processes accompanied by dramatic changes in electronic absorption spectra

Experimental data in support of characterization of the CePO4 dispersion into transparent PMMA/PU IPNs by the sequential route

© 2018 This article is focused on the complementary data referring to the article “Dispersion of upconverting nanostructures of CePO4 using rod and semi-spherical morphologies into transparent PMMA/PU IPNs by the sequential route”. It contains the XPS data of CePO4 photographs and DSC thermograms of transparent PMMA/PU IPNs as well as with CePO4 dispersed in different wt.%, Confocal laser scanning micrographs, transmission electron microscopy (TEM), optical images of surface, and visual inspection (photographs) before and after aging of hybrid materials

Dispersion of upconverting nanostructures of CePO4 using rod and semi-spherical morphologies into transparent PMMA/PU IPNs by the sequential route

Upconverting luminescent poly (methylmethacrylate) (PMMA)/poly (urethane) (PU) interpenetrating polymer network (IPN) nanohybrids were prepared using a sequential polymerisation incorporating different wt.% of cerium phosphate (CePO 4 ) nanoparticles. The effect of miscibility/compatibility of the different PMMA/PU ratios, the addition and dispersion of rod and semi-spherical nanostructures in as well as the performance of selected IPNs under accelerated aging were studied using morphological, emission, thermal and mechanical studies. Structural studies revealed that there were physical interactions between C[dbnd]O groups and CePO 4 in PMMA/PU IPNs. The addition of a higher wt.% of nanostructures was found to decrease the transparency of the IPNs. Resulting PMMA/PU/CePO 4 IPN nanohybrids are photoluminescent under UV-light, supporting the prolongate of lifetime while maintaining the mechanical properties after being subjected to accelerated weathering. The addition of semi-spherical particles resulted in a more stable materials after accelerated weathering than nanorods

Advantages of block copolymer synthesis by RAFT-controlled dispersion polymerization in supercritical carbon dioxide

Reversible addition-fragmentation chain transfer (RAFT)-controlled block copolymer synthesis using dispersion polymerization in supercritical carbon dioxide (scCO2) shows unprecedented control over blocking efficiency. For PMMA-b-PBzMA and PMMA-b-PSt the blocking efficiency was quantified by measuring homopolymer contaminants using the techniques of GPC deconvolution, gradient polymer elution chromatography (GPEC), and GPC dual RI/UV detection. A new, promising method was also developed which combined GPC deconvolution and GPEC. All techniques showed that blocking efficiency was significantly improved by reducing the radical concentration and target molecular weight. Estimated values agreed well with (and occasionally exceeded) theory for PMMA-b-PBzMA. The heterogeneous process in scCO2 appeared to cause little or no further hindrance to the block copolymerization procedure when reaction conditions were optimized. High blocking efficiencies were achieved (up to 82%) even at high conversion of MMA (>95%) and high molecular weight. These data compare favorably to numerous published reports of heterogeneous syntheses of block copolymers