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A new class of efficient stationary phase has been investigated for use in the liquid chromatographic separation of low molecular weight analytes and high molecular weight biomolecules, based on the application of immobilised stimuli-responsive polymers (SRPs). To this end, two polymeric units, namely poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) and poly(acrylic acid) (PAA) were tethered to a triazine core. The derived poly(2-dimethyl-aminoethyl methacrylate)-block-poly(acrylic acid) (PDMAEMA-b-PAA), as a diblock co-polymer, was then immobilised onto the surface of porous silica particles. The performance of this microparticulate adsorbent was evaluated under various temperature, ionic strength and/or pH conditions in packed columns in a high-performance liquid chromatography (HPLC) format. Baseline separations of a variety of low molecular weight analytes were achieved at different temperatures with this SRP-based adsorbent using 10 mM sodium phosphate buffer, pH 6.0, as the mobile phase. Moreover, when the ionic strength of the mobile phase was increased to 40 mM sodium phosphate buffer, pH 6.0, similar temperature changes resulted in further increases in resolution for the hydrophobic analytes. In addition, changes in the pH of the mobile phase from pH 6.0 to pH 8.0 led to significant changes in selectivity of the analytes, including reversal in their elution orders. Upon increasing the temperature, the retention times of all analytes decreased but without loss of resolution. These findings can be attributed to the consequence of the immobilised copolymer undergoing a phase transition at its lower critical solution temperature (LCST), which leads to changes in its solvated structure, including how the electrostatic, hydrophilic and hydrophobic regions/domains of the copolymer are exposed to the bulk mobile phase. Thermodynamic data were indicative of a temperature-related re-organisation of the structure of the immobilised PDMAEMA-b-PAA stationary phase with exothermic binding of the analytes occurring at temperatures below the lower critical solution temperature (LCST). In this manner; changes in the system temperature could directly be used to manipulate the adsorption and desorption behaviour of these analytes with this stimuli-responsive, polymer-modified porous silica stationary phase. Additional studies with several proteins further documented the versatility of these stimuli-responsive separation materials. The results indicated that these separations could be tuned by variation of the temperature with fully aqueous mobile phases at specific ionic strength and pH values, without the need to use an organic solvent as a component in the mobile phase., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The influence of mPEG-PCL and mPEG-PLGA on encapsulation efficiency and drug-loading of nanoparticles was very important. SN-38 NPs were prepared from a series of diblock copolymers: mPEG1000-PLGA2000, mPEG2000-PCLs, mPEG5000-PCLs, mPEG2000-PLGAs, and mPEG5000-PLGAs by the thin film-hydration method. The prepared nanoparticles were characterized by morphology, size, encapsulation efficiency, drug-loading, and in vitro release behavior. This experiment suggested that the encapsulation efficiency and drug-loading of SN-38 NPs were attained the maximum values when the ratio of hydrophilic to hydrophobic block was between 1:2 and 1:3.

This article describes the synthesis and characterization of a novel 'schizophrenic' diblock copolymer [poly(2-succinyloxyethyl methacrylate)- b -poly[( N -4-vinylbenzyl), N , N -diethylamine)]; PSEMA- b -PVEA] via reversible addition of fragmentation chain transfer (RAFT) polymerization technique. The chemical structures of all samples as representatives were characterized by means of Fourier transform infrared (FTIR), and 1 H nuclear magnetic resonance (NMR) spectroscopies. The molecular weights of PHEMA and PVEA segments were calculated to be 9770 and 12,630 gmol -1 , respectively, from 1 H NMR spectroscopy. The self-assembly behavior of the synthesized PSEMA- b -PVEA diblock copolymer was investigated by means of 1 H NMR spectroscopy, dynamic light scattering (DLS) measurements, and transmission electron microscopy (TEM) observation. The average sizes of the PSEMA- b -PVEA micelles at pHs 3.0, 6.0, and 10.0 were obtained to be 294, 237, and 201 nm, respectively, from DLS analysis. The zeta potential measurements at various pHs demonstrated that the synthesized PSEMA- b -PVEA diblock copolymer has zwitterionic properties, and the range of isoelectric point's (IEP's) was determined as 5.8-7.3. It is expected that the synthesized PSEMA- b -PVEA diblock copolymer considered as a prospective candidate in nanomedicine applications such as drug delivery, mainly due to its excellent 'schizophrenic' micellization behavior.

An effective approach for the dispersion of hydrophilic cellulose nanofiber (CNF) in hydrophobic high-density polyethylene (HDPE) is presented using adsorption of a diblock copolymer dispersant. The dispersant consists of both resin compatible poly(lauryl methacrylate) (PLMA) and cellulose interactive poly(2-hydroxyethyl methacrylate) blocks. The PLMA-adsorbed CNFs are characterized by FT-IR and contact angle measurement, revealing successful hydrophobization. X-ray CT imaging shows there are apparently less CNF aggregates in the nanocomposites if adding amount of the dispersant was enough. The good dispersion results in a high mechanical reinforcement, corresponding to 140% higher Young's modulus and 84% higher tensile strength than the neat HDPE. This approach is broadly applicable and allows for easy manufacturing process for strong and lightweight CNF-reinforced nanocomposite materials.

We report broadband pH-sensing organic field-effect transistors (OFETs) with the polymer-dispersed liquid crystal (PDLC) sensing layers. The PDLC layers are prepared by spin-coating using ethanol solutions containing 4-cyano-4'-pentyl-biphenyl (5CB) and a diblock copolymer (PAA-b-PCBOA) that consists of LC-philic block [poly(4-cyano-biphenyl-4-oxyundecyl acrylate) (PCBOA)] and acrylic acid block [poly(acrylic acid) (PAA)]. The spin-coated sensing layers feature of 5CB microdomains (<5 μm) encapsulated by the PAA-b-PCBOA polymer chains. The resulting LC-integrated-OFETs (PDLC-i-OFETs) can detect precisely and reproducibly a wide range of pH with only small amounts (10-40 μL) of analyte solutions in both static and dynamic perfusion modes. The positive drain current change is measured for acidic solutions (pH < 7), whereas basic solutions (pH > 7) result in the negative change of drain current. The drain current trend in the present PDLC-i-OFET devices is explained by the shrinking-expanding mechanism of the PAA chains in the diblock copolymer layers.

A fluorinated diblock copolymer of methyl methacrylate (MMA) and 2,2,2-trifluoroethyl methacrylate (TFEMA) was prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization in the presence of cumyl dithiobenzoate (CDB) as the chain transfer agent (CTA). ¹H NMR spectroscopy, Fourier transform infrared spectroscopy, gel permeation chromatography and different scanning calorimetry were used to characterize the block copolymers obtained. Contact angle measurement indicated that the diblock copolymer has considerable hydrophobicity (¹water = 104.3°) and lipophobicity (θoil = 80.0°). The results are almost the same as those for PTFEMA and superior to those for a random copolymer of MMA and TFEMA. It was also found that P(MMA-b-TFEMA) has high thermostability. The self-assembly behaviour of the copolymer in selective solvents was evaluated by SEM, and stable micelles with a diameter of 400-600 nm were observed when the copolymer content was approximately 0.2 wt.%. Comparison studies with P(MMA-b-TFEMA), PTFEMA and PMMA revealed that the copolymer with a controllable distribution of fluorine atoms possesses a good performance. [ABSTRACT FROM AUTHOR]

Time‐resolved grazing‐incidence smallangle X‐ray scattering is used to investigate the structural changes in a lamellar block copolymer thin film during solvent vapor treatment and drying. Drastic changes proceed at the film surface: During solvent vapor treatment, the film surface is covered by one of the blocks. During drying, this thin surface layer retracts, and protrusions of the other block are formed. Further details can be found in the article by J. Zhang, D. Posselt, A. Sepe, X. Shen, J. Perlich, D.‐M. Smilgies, and C. M. Papadakis* on page 1289. [ABSTRACT FROM AUTHOR]

Recently, there has been renewed interest in the coupling between geometry and topological defects in crystalline and striped systems. Standard lore dictates that positive disclinations are associated with positive Gaussian curvature, whereas negative disclinations give rise to negative curvature. Here, we present a diblock copolymer system exhibiting a striped columnar phase that preferentially forms wrinkles perpendicular to the underlying stripes. In free-standing films this wrinkling behavior induces negative Gaussian curvature to form in the vicinity of positive disclinations.

Nanoscale assemblies composed of different types of nanoparticles (NPs) can reveal interesting aspects about material properties beyond the functions of individual constituent NPs. This research direction may also represent current challenges in nanoscience toward practical applications. With respect to the assembling method, synthetic or biological nanostructures can be utilized to organize heterogeneous NPs in specific sites via chemical or physical interactions. However, those assembling methods often encounter uncontrollable particle aggregation or phase separation. In this study, we anticipated that the self-segregating properties of block copolymer micelles could be particularly useful for organizing heterogeneous NPs, because the presence of chemically distinct domains such as the core and the corona can facilitate the selective placement of constituent NPs in separate domains. Here, we simultaneously functionalized the core and the corona of micelles by Au NPs and Ag NPs, which exhibited plasmonic and catalytic functions, respectively. Our primary question is whether these plasmonic and catalytic functions can be combined in the assembled structures to engineer the kinetics of a model chemical reaction. To test this hypothesis, the catalytic reduction of 4-nitrophenol was selected to evaluate the collective properties of the micellar assemblies in a chemical reaction.

Disposal of the environmentally dangerous metal oxide suspensions from the waste water is an essential problem. The polymers adsorption can be one of the most effective and suitable methods. In the presented paper the ionic diblock copolymers impact on the Cr2O3 suspensions was investigated. The copolymer adsorption layers structure was determined on the basis of the adsorption and electrokinetic (surface charge density and zeta potential) tests. The polymers adsorption amount was measured using the static method from aqueous solutions. Additionally, the application of the turbidimetric method enabled determination of the interactions between the system constituents. Analysis of this data allows the estimation of the most probable stabilization (or destabilization) mechanism of the Cr2O3 suspensions in the presence of the studied macromolecular compounds. Hence, the Cr2O3 suspensions are unstable in the presence of the anionic copolymer at pH 3 and the cationic one in the alkaline medium., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Abstract: We present a simple method for the production of magnetic antidot arrays utilizing polystyrene-poly-2-vinylpyridine micelles filled with amorphous . By dip coating, a micellar monolayer is deposited onto Co/Pt multilayers. A hexagonal pattern with periodicity of 80nm is obtained. By ion etching the micelle layer is transformed into an antidot array due to preferred sputtering of the core. Further ion bombardment transfers the pattern into the magnetic film and leads to a reorientation of the perpendicular to in-plane easy axis which is attributed to intermixing of the Co/Pt multilayers. [Copyright &y& Elsevier]

Pre-adsorbed branched brush layers were formed on silica surfaces by adsorption of a diblock copolymer consisting of a linear cationic block and an uncharged bottle-brush block. The charge of the silica surface was found to affect the adsorption, with lower amounts of the cationic polyelectrolyte depositing on less charged silica. Cleaning under basic conditions rendered surfaces more negatively charged (more negative zeta-potential) than acid cleaning and was therefore used to increase polyelectrolyte adsorption. The structure of adsorbed layers of the diblock copolymer was as determined by neutron reflectometry found to be about 70 nm thick and very water rich (97%). Interactions between the anionic surfactant sodium dodecylsulfate (SDS) and such pre-adsorbed diblock polymer layers were studied by neutron reflectometry and by optical reflectometry. Optical reflectometry was also used for deducing interactions between the individual blocks of the diblock copolymer and SDS at the silica/aqueous interface. We find that SDS is readily incorporated in the diblock copolymer layer at low SDS concentrations, and preferentially co-localized with the cationic block of the polymer next to the silica surface. At higher SDS concentrations some desorption of polyelectrolyte/surfactant complexes takes place., (Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.)

Two copolymer/SiO2 hybrids are prepared by growing SiO2 on the template of well -structured diblock copolymer PMMA-b-PMPS using a "grafting-to" approach. PMMA-b-PMPS is obtained by atom transfer radical polymerization (ATRP) of methyl methacrylate (PMMA) and 3-(trimethoxysilyl)propyl methacrylate (PMPS) using a brominated initiator end group termed 1H,1H,2H,2H-heptadecafluoro (F-Br) and a conventional initiator of ethyl 2-bromoisobutyrate (EBiB), respectively. The "grafting-to" approach is controlled at HCl for 24h by hydrolysis and condensation of Si(OCH3)3 groups in PMPS with tetraethyl orthosilicate (TEOS) to gain both hybrids of F-PMMA-b-PMPS/SiO2 (by F-Br initiator) and E-PMMA-b-PMPS/SiO2 (by EBIB initiator). Comparatively, a little amount of fluorine content provided by F-Br is able to tighten the size of self-assembled micelles, to improve wettability and the viscoelasticity of F-PMMA-b-PMPS film due to F-Br migrating onto the film surface. Therefore, the surface of F-PMMA-b-PMPS film is sufficiently hydrophobic (99° and Δf=2941Hz) than E-PMMA-b-PMPS film (94°and Δf=4820Hz), and the viscoelasticity of the adsorbed layer for F-PMMA-b-PMPS (ΔD/Δf=-0.112) film is much harder than E-PMMA-b-PMPS/SiO2 (ΔD/Δf=-0.071). On the other hand, the cross-linked silica in PMMA-b-PMPS/SiO2 could also increase water contact angels of films (100-107°) and decrease the water absorption (Δf=704-798Hz). The influence on the viscoelasticity of the adsorbed layer by the fluorine group is much more obvious than the cross-linked silica, therefore F-PMMA-b-PMPS/SiO2 (ΔD/Δf=-0.347) and F-PMMA-b-PMPS (ΔD/Δf=-0.112) films have harder adsorbed layer than E-PMMA-b-PMPS/SiO2 (-0.071) and F-PMMA-b-PMPS films (-0.042). However, compared with a slightly improvement in thermo stability by F-Br, the cross-linked silica in PMMA-b-PMPS/SiO2 performs significantly improving thermal decomposition temperature at 300°C and 350°C., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Alginate-based microcapsules are being proposed for treatment of many types of diseases. A major obstacle however in the successes is that these capsules are having large lab-to-lab variations. To make the process more reproducible, we propose to cover the surface of alginate capsules with diblock polymers that can form polymer brushes. In the present study, we describe the stepwise considerations for successful application of diblock copolymer of polyethylene glycol (PEG) and poly-L-lysine (PLL) on the surface of alginate beads. Special procedures had to be designed as alginate beads are hydrophilic and most protocols are designed for hydrophobic biomaterials. The successful attachment of diblock copolymer and the presence of PEG blocks on the surface of the capsules were studied by fluorescence microscopy. Longer time periods, that is, 30-60 min, are required to achieve saturation of the surface. The block lengths influenced the strength of the capsules. Shorter PLL blocks resulted in less stable capsules. Adequate permeability of the capsules was achieved with poly(ethylene glycol)-block-poly(L-lysine hydrochloride) (PEG454-b-PLL100) diblock copolymers. The capsules were a barrier for immunoglobulin G. The PEG454-b-PLL100 capsules have similar mechanical properties as PLL capsules. Minor immune activation of nuclear factor κB in THP-1 monocytes was observed with both PLL and PEG454-b-PLL100 capsules prepared from purified alginate. Our results show that we can successfully apply block copolymers on the surface of hydrophilic alginate beads without interfering with the physicochemical properties., (Copyright © 2013 The Authors. Journal of Biomedical Materials Research Part A Published by Wiley Periodicals, Inc.)

Using self-assembly of block copolymer micelle loaded metal precursors, combined with a seeding growth route, we have developed a novel approach to create ordered metal nanoparticle (NP) arrays of controllable size over large areas (~80 mm(2)) on solid substrates. Atomic force microscopy (AFM), UV-Vis extinction spectrophotometry, and theoretical simulations were systematically carried out to determine the size and pattern of NP arrays, and locate the localized surface plasmon resonance (LSPR) peak. By tuning the molar ratios of precursors, hexagonal arrays of AuNPs of mean heights of 5.2±0.6 nm, 8.3±1.7 nm, and 10.0±2.1 nm were obtained by self-assembly of poly(styrene-b-2-vinyl pyridine) micelle-loaded gold salt on glass. Further seeding growth was then used to enlarge the AuNPs to heights of 25.7 and 33 nm and decrease the edge-to-edge inter-particle spacing. The optical response of AuNP arrays was determined by measuring and computing their absorbance spectra as a function of the cover medium refractive index over the range from 1 to 1.55; the measured spectra agree very well with the computations. The resonance wavelength red-shifts as the medium refractive index increases and the bulk sensitivity of the arrays increases with increasing AuNP size. When the edge-to-edge inter-particle spacing decreased to ~50 nm, coupling of adjacent AuNPs became apparent, as a shoulder which developed in the spectra. Also, the AuNPs were found to be embedded in the substrate glass by about ~20-30%, as determined by comparing the experimental and computed bulk sensitivities. The fabrication technique devised is suitable for low-cost mass-manufacturing of large area arrays of ordered high-quality AuNPs on a substrate for biosensor or other applications., (Crown Copyright © 2013. Published by Elsevier Inc. All rights reserved.)

The structural evolution in poly(styrene-b-butadiene) (P(S-b-B)) diblock copolymer thin films during solvent vapor treatment is investigated in situ using time-resolved grazing-incidence small-angle X-ray scattering (GISAXS). Using incident angles above and below the polymer critical angle, structural changes near the film surface and in the entire film are distinguished. The swelling of the film is one-dimensional along the normal of the substrate. During swelling, the initially perpendicular lamellae tilt within the film to be able to shrink. In contrast, at the film surface, the lamellae stay perpendicular, and eventually vanish at the expense of a thin PB wetting layer. During the subsequent drying, the perpendicular lamellae reappear at the surface, and finally, PS blocks protrude. By modeling, the time-dependent height of the protrusions can be quantitatively extracted., (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We report a biocompatible polysiloxane containing amphiphilic diblock copolymer, poly(ethylene oxide)-block-poly(gamma-methacryloxypropyltrimethoxysilane) (PEO-b-PgammaMPS), for coating and stabilizing nanoparticles for biomedical applications. Such an amphiphilic diblock copolymer that comprises both a hydrophobic segment with "surface anchoring moiety" (silane group) and a hydrophilic segment with PEO (M(n) = 5000 g/mol) was obtained by the reversible addition-fragmentation chain transfer (RAFT) polymerization using the PEO macromolecular chain transfer agent. When used for coating paramagnetic iron oxide nanoparticles (IONPs), copolymers were mixed with hydrophobic oleic acid coated core size uniformed IONPs (D = 13 nm) in cosolvent tetrahydrofuran. After being aged over a period of time, resulting monodispersed IONPs can be transferred into aqueous medium. With proper PgammaMPS block length (M(n) = 10 000 g/mol), polysiloxane containing diblock copolymers formed a thin layer of coating (approximately 3 nm) around monocrystalline nanoparticles as measured by transmission electron microscopy (TEM). Magnetic resonance imaging (MRI) experiments showed excellent T(2) weighted contrast effect from coated IONPs with a transverse relaxivity r(2) = 98.6 mM(-1) s(-1) (at 1.5 T). Such thin coating layer has little effect on the relaxivity when compared to that of IONPs coated with conventional amphiphilic copolymer. Polysiloxane containing diblock copolymer coated IONPs are stable without aggregation or binding to proteins in serum when incubated for 24 h in culture medium containing 10% serum. Furthermore, a much lower level of intracellular uptake by macrophage cells was observed with polysiloxane containing diblock copolymers coated IONPs, suggesting the reduction of nonspecific cell uptakes and antibiofouling effect.