Neoglycopolymers Based on 4‐Vinyl‐1,2,3‐Triazole Monomers Prepared by Click Chemistry

The synthesis of a new glycomonomer based on mannose, prepared via CuAAC, is reported. The resulting 1,2,3‐triazole linkage between mannose and the polymer backbone ensures the formation of highly stable glycopolymers, which will not undergo hydrolysis. The monomer 2′‐(4‐vinyl‐[1,2,3]‐triazol‐1‐yl)ethyl‐O‐α‐D ‐mannopyranoside was polymerized in the presence of a RAFT agent – 3‐benzylsulfanylthiocarbonylsulfanyl propionic acid – to yield well‐defined polymers with molecular weights up to 51 500 g mol^?1 and a PDI of 1.16. The resulting polymer was employed as a macroRAFT agent in the polymerization of NIPAAm in order to generate thermo‐responsive block copolymers, which undergo reversible micelle formation at elevated temperatures. The rapid interaction between the polymers prepared and ConA confirms the high affinity of these structures to proteins. While the linear glycopolymers already undergo a fast complexation with ConA, the reported rates have found to be exceeded by the micellar glycopolymer structure presented in the current contribution.

     

Self‐Assembling Nanomaterials using Magnetic Nanoparticles Modified with Polystyrene Brushes

Magnetic nanomaterials have been studied in order to generate novel nanocomposites that display both the magnetic properties of the nanoparticles and the ability to self‐assemble of the amorphous block copolymer matrix. Towards this goal, iron oxide magnetic nanoparticles have been modified with PS brushes by ATRP in order to improve both the dispersion and the affinity of the nanoparticles with one of the blocks of a polystyrene‐block‐polybutadiene‐block‐polystyrene block copolymer. This method of preparation of nanocomposites opens new strategies for the generation of magnetic nanomaterials. The samples are characterized using DSC and atomic and magnetic force microscopies.

     

Acid‐Degradable Core‐Crosslinked Micelles Prepared from Thermosensitive Glycopolymers Synthesized via RAFT Polymerization

A thermoresponsive block copolymer, namely poly(acryloyl glucosamine)‐block‐poly(N‐isopropylacryamide) (PAGA₁₈₀‐b‐PNIPAAM₃₅₀) was simultaneously self‐assembled and crosslinked in aqueous medium via RAFT polymerization at 60 °C to afford core‐crosslinked micelles exhibiting a glycopolymer corona and a PNIPAAM stimuli‐responsive core. An acid‐labile crosslinking agent, 3,9‐divinyl‐2,4,8,10‐tetraoxaspiro[5.5]undecane, was employed to generate thermosensitive and acid‐degradable core‐shell nanoparticles. Stable against degradation at pH = 6 and 8.2, the resulting core crosslinked micelles readily hydrolyzed into well‐defined free block copolymers at lower pH (30 min and 12 h respectively at pH = 2 and 4).

     

Synthesis of a Photoresponsive Liquid‐Crystalline Polymer Containing Azobenzene

The synthesis of an oriented liquid‐crystalline photoresponsive polymer, prepared by polymerization of mono‐ and di‐acrylates, both of which contain azobenzene chromophores, is reported. The prepared free‐standing polymer film shows strong reversible photoinduced deformation upon exposure to unpolarized UV light at 366 nm, as a result of an optically induced isomeric change of the azobenzene moieties in the polymer network. The synthesis process is relatively simple and more efficient compared to conventional ones, and can be used to synthesize other liquid‐crystalline photoresponsive polymers. The use of this photoresponsive polymer film as an optical high‐pass/low‐pass switch under UV or natural light irradiation for a laser beam is demonstrated. This photoresponsive polymer may have applications in robotic systems, artificial muscles, and actuators in microelectromechanical systems (MEMS) and labs on chips.

     

Phantom Chain Simulations of Realistically Sized Polymer‐Based Nanocomposites

Summary: Phantom chain MC simulations have been performed for realistically sized systems of polymer chains filled with solid nanoparticles. The results of the simulations and simple theoretical considerations are used to rationalize a number of parameters relevant to the characterization of these systems. Even when the average number of nanoparticles in contact with a chain is very small (much less than unity), the nanoparticles are nodes of highly interconnected transient networks bridged by the polymer chains.

     

Construction of Large‐Scale Highly Ordered Macroporous Monoliths of π‐Conjugated Polymers

Large scale of well‐ordered macroporous π‐conjugated polymer monoliths have been successfully prepared through a new approach using micrometer‐sized naphthalene crystals as templates. The macroporous monoliths of poly(p‐phenylenevinylene) (PPV) and poly(p‐phenyleneethynylene) (PPE) grew along the unidirectional freezing direction inside the template naphthalene crystals which lead to the formation of controlling morphologies and homogeneous diameters. The polymer monoliths show straight and lamella macroporous structures. The diameters of pores and the thickness of pore walls can be controlled by tuning the freezing temperature.

     

Macromolecular Recognition of Cyclodextrin: Inversion of Selectivity of β‐Cyclodextrin toward Adamantyl Groups Induced by Macromolecular Chains

Interaction of β‐cyclodextrin (β‐CD) with alternating copolymers (pAdMA and pAdPhMA) of sodium maleate with adamantyl (Ad) and with adamantylphenyl (AdPh) vinyl ether has been investigated by several NMR techniques. Comparing the apparent association constants (K) for the polymers with the K for the model compounds, which are determined by the analysis of ¹H NMR and isothermal titration calorimetry data, respectively, the selectivities of β‐CD toward Ad and AdPh moieties are contrasting for the model and polymer systems. This phenomenon is described by circular dichroism and 2D NMR as follows; the most stable inclusion complex for the β‐CD/AdPh model system is extremely destabilized for the corresponding polymer system because of competition with hydrophobic interaction between neighboring AdPh moieties.

     

Polymerization of Aniline by Auric Acid: Formation of Gold Decorated Polyaniline Nanoballs

Summary: We report a new method for the preparation of polyaniline nanoballs by using HAuCl₄ as an oxidizing agent. During the reaction, aniline is oxidized and forms polyaniline whilst the hydrogen tetrachloroaurate is reduced and forms gold nanoparticles. These gold nanoparticles are found to decorate the nanoballs.

The resultant precipitate and corresponding TEM image of the gold‐nanoparticle covered polyaniline nanoball.     

Color Indicator for Supramolecular Polymer Chemistry: Phenolphthalein‐Containing Thermo‐ and pH‐Sensitive N‐(Isopropyl)acrylamide Copolymers and β‐Cyclodextrin Complexation

The copolymerization parameters of N‐(isopropyl)acrylamide ( 1 ) and N‐(2‐hydroxy‐5‐(1‐(4‐hydroxyphenyl)‐3‐oxo‐1,3‐dihydroisobenzofuran‐1‐yl)benzyl)acrylamide ( 2 ) are determined. For both monomers, the homoaddition proceeds slightly faster than the heteroaddition step; however, the polymer formation occurs in a statistic fashion. Copolymers of different compositions are prepared and the cloud points are determined. Thereby, a significant influence of the concentration of monomer 2 and the pH value is found. For the first time, the complexation of polymer attached phenolphthalein by β‐cyclodextrins is shown. Furthermore, it is possible to achieve a decomplexation by the addition of suitable guest molecules. Both procedures can be followed with the naked eye.

     

A New Strategy for the Synthesis of Polyaniline Nanostructures: From Nanofibers to Nanowires

A new approach for the synthesis of polyaniline (PANI) nanostructures under UV light illumination has been developed, which is the first report of a templateless chemical process for preparing pure PANI nanowires. The acceleration effect of photo‐assistance on the polymerization can promote the homogeneous nucleation and elongation of the nanofibers and nanowires, leading to easy preparation of tunable diameters of the nanowires and nanofibers of PANI.

     

Self‐Assembled Monolayer Formed by a Rhenium Complex Containing Hyperbranched Polymer

Summary: The synthesis of a hyperbranched polymer containing a rhenium bipyridine complex is reported. The polymer was synthesized from a monomer that contains two chlorotricarbonyl rhenium(I ) bipyridine moieties and a stilbazole ligand, and the polymer was formed by the coordination reaction in one single step. Gel permeation chromatography results showed that the resulting polymer had a strong interaction with the column packing material, which was reduced when the eluent was added with an electrolyte. Both atomic force microscopy and laser light scattering showed that the size of the polymer molecules was in the range between 25–30 nm. A monolayer of polymer molecules could form on a pretreated substrate by the self‐assembly process, which can serve as the building block for multilayer ultrathin film devices.

The metal‐containing hyperbranched polymer synthesized here.     

Polymer Brushes with Phototriggered and Phototunable Swelling and pH Response

Photolabile polymer brushes with tailored length containing a photoremovable protecting group (NVOC) are prepared via the SI‐ATRP method. Upon light irradiation, the NVOC group is removed to generate controlled densities of free amine groups (PAMA) randomly distributed along the brush. The presence of the ionizable groups induces a photo‐triggered swelling response. The swelling degree can be tuned by the irradiation dose. A dual (light and pH), tunable response is demonstrated.

     

Formation of Silica/Poly(p‐dioxanone) Microspheres by Surface‐Initiated Polymerization

A polymeric film of a biodegradable poly(p‐dioxanone) was grown from 490 nm silica particles by monolayer formation via self‐assembly of hydroxy‐terminated triethoxysilane and subsequent surface‐initiated ring‐opening polymerization of p‐dioxanone. The resulting silica/poly(p‐dioxanone) hybrid particles were characterized by means of ¹H NMR spectroscopy, IR spectroscopy, thermogravimetric analysis, field‐emission scanning electron microscopy, and energy‐dispersive X‐ray spectroscopy.

     

Storage Modulus and Surface Morphology of Poly(vinyl alcohol)/Alumina Hybrid Hydrogels

The storage moduli, shear moduli and surface morphologies of poly(vinyl alcohol) (PVA) and alumina hybrid hydrogels were investigated. The storage moduli of hybrid hydrogels with higher alumina contents were found to be 1.5 times higher than those of PVA gels. This increase in modulus might be attributed to the cohesion of alumina to the PVA network.

SEM photograph of Al7 PVA/alumina hybrid hydrogel. The photograph was taken with a magnification of × 220.     

Direct Melt Intercalation of Polylactide Chains into Nano‐Galleries: Interlayer Expansion and Nano‐Composite Structure

Summary: The polylactide‐based nano‐composites were prepared via melt extrusion method using different types of intercalants and nano‐fillers having different surface charge density. In order to understand the direct polymer melt intercalation into the nano‐galleries, the interdigitated layer structure of the organically modified layered filler (OMLF), where the intercalants are oriented with some inclination to the host layer in the interlayer space, was proposed. After polymer melt intercalation, the smaller initial interlayer opening led to the larger interlayer expansion, suggesting the large amount of the intercalation of the polymer chains. Consequently, the nano‐composite exhibited finer dispersion of the nano‐fillers when compared with the nano‐composites prepared from OMLFs with larger initial interlayer opening.

Illustration of a model of interlayer structure of the qC₁₄(OH) in gallery space of HTO.     

A Cationic Water‐Soluble Poly(p‐phenylenevinylene) Derivative: Highly Sensitive Biosensor for Iron‐Sulfur Protein Detection

Summary: A new water‐soluble cationic ammonium‐functionalized poly(p‐phenylenevinylene) (PPV‐NEtMe) was successfully synthesized and exhibited high sensitivity (K_sv = 6.9 × 10⁷ M ⁻¹) on rubredoxin, a type of anionic iron‐sulfur (Fe‐S) proteins. Further investigation showed that the biosensitivity of the cationic conjugated polymer is strongly dependent on the nature of the buffer solution and the concentration of the conjugated polymer used in the analyses.

The schematic diagram of anionic rubredoxin detected by PPV‐NEtMe.     

Facile Access to an Efficient Solid‐Supported Click Catalyst System Based on Poly(ethyleneimine)

A novel heterogeneous copper(I) catalyst system, which is based on readily available poly(ethyleneimine), has been used as a recyclable catalyst for Cu(I) catalyzed “click” 1,3 dipolar cycloaddition reactions of azides and alkynes in organic media. Branched poly(ethyleneimine) was first methylated and then cross‐linked with 1,9‐dibromononane. Subsequently, after the immobilization of Cu(I)Br, this system was applied for heterogeneous copper catalyzed click chemistry of a few model reagents and polymeric compounds.

     

Unprecedented Blue Intrinsic Photoluminescence from Hyperbranched and Linear Polyethylenimines: Polymer Architectures and pH‐Effects

The intrinsic photoluminescence properties of hyperbranched polyethylenimines (PEIs) and their linear counterpart (LPEIs) have been studied in absence of any classical fluorescent probes. The comparison of the inherent fluorescence emission between hyperbranched polyethylenimines and their linear analogues demonstrates that linear polyamines are capable of producing strong intrinsic photoluminescence species having long excited lifetimes without need of having a tridimensional‐branched structure. The creation of inherently fluorescent polymeric centers from hyperbranched and linear polyethyleimines can be modulated by specific chemical modification and oxidation of amine groups as well as by adjusting the acidity of the polymer.