Summary: Water‐soluble biomimetic chitosan derivative conjugating zwitterionic phosphorylcholine was efficiently prepared through Atherton‐Todd reaction under the mild conditions, and the possible formation mechanism of zwitterionic product was related to the nucleophilic attack of adjacent 3‐hydroxyl on the D ‐glucosamine residue to phosphorus with the help of base. UV absorption and melting behaviors of DNA/phosphorylcholine‐bound chitosan derivative showed that the phosphorylcholine‐bound chitosan derivative could be a new carrier for long‐circulating macromolecular drug delivery.
Nylon‐6/poly(ethylene terephthalate) (PET) ultra‐multi‐island sea–island conjugated melt‐spun fibers are flow‐drawn at a draw ratio of 174 with heating by CO2 laser irradiation. Continuous PET nanofibers that have a diameter of 39 nm could be obtained from the flow‐drawn fiber with further drawing and removal of the sea component. In addition, the drawn fiber has a strength of 0.54 GPa. This result shows that a PET nanofiber having a strength almost equal to that of a conventional PET fiber can be obtained by the combination of conjugate‐melt‐spinning and laser‐heated flow‐drawing.
This paper reports a new polyimide design with high internal free volume elements for fast mass transport simultaneously with high selectivity. Here, we show that the polymer design using a three‐dimensional rigid molecular structure having internal void space can lead to the formation of high fractional free volume with proper cavity size to separate small gas molecules with high selectivities as high permeabilities. These findings could strongly impact emerging gas separation applications using polymeric membranes such as natural gas purification and biogas purification to get clean energy resources.
α‐Methoxy‐ω‐alkyne poly(ethylene glycol) (PEG) was tagged with pendent N‐hydroxy‐succinimidyl activated esters by photografting of a molecular clip. This easily synthesized heterofunctional PEG was found to be a versatile building block for (i) conjugation with an amino derivative and (ii) grafting to azido functional aliphatic polyesters backbone by Huisgen's 1,3‐dipolar cycloaddition. This original combination of “clip” and “click” reactions provides a versatile and straightforward pathway for the synthesis of functional amphiphilic and degradable copolymers valuable for biomedical applications such as in drug‐delivery.
Cross‐linked lyotropic liquid crystal (LLC) assemblies represent a new class of polymer materials for membrane applications. These materials are formed by the phase‐segregation and self‐assembly of polymerizable amphiphiles in water into condensed ordered ensembles that can be cross‐linked in situ with retention of microstructure. The resulting LLC polymer networks have ordered, nanometer‐scale aqueous and cross‐linked organic domains, which can be used to affect gas solubility and diffusivity through the polymer to help separate molecules via the solution–diffusion mechanism. The open aqueous domains can also be used for pore transport and size exclusion with resolution on the molecular size level. The use and application potential of cross‐linked LLC assemblies as gas separation membranes, selective vapor barrier materials, and water nanofiltration and desalination membranes are presented.
Hierarchical poly(3‐hexylthiophene)(P3HT)/carbon nanotube (CNT) supramolecular structures were fabricated through a bottom‐up CNT induced P3HT crystallization strategy. P3HT nanowires growing perpendicular from CNT surface have uniform width and height. The density and the length of these nanowires can be controlled by tuning the P3HT/CNT mass ratio. The quasi‐isothermal crystallization process monitored by in situ UV–Vis spectroscopy indicates that CNTs can greatly enhance the P3HT crystallization, and the P3HT nanowire formation follows first‐order kinetics. Such bottom‐up strategy provides a general approach to build 2D functional conductive supramolecular structures that will lead to numerous applications in nanoscale electronics.
Well‐defined poly(ethylene oxide)s (PEOs) bearing reactive sites regularly distributed along the chain have been synthesized by the polycondensation of PEO containing a central tertiary amino group with dichloromethane, followed by quaternization with suitable reagents to obtain polyzwitterionic or cationic PEOs with alkyl, allyl, or fluorocarbon pendant groups. The pendant allyl groups have been converted into primary amino groups by reaction with 2‐aminoethanethiol hydrochloride to obtain polyamino‐functionalized PEO.
Polyfunctional PEOs bearing different pendant groups. 相似文献
Polycondensation of 1‐(2‐pyrimidinyl)pyrrole with 2,7‐dibromo‐9,9‐dioctylfluorene via Ru‐catalyzed direct arylation gives the corresponding conjugated polymer with a molecular weight of 19 800 in 86% yield. The introduction of directing group, 2‐pyrimidinyl substituent, into the pyrrole monomer induces ortho‐metalation and provides the site‐selective direct arylation polycondensation at the α‐position of pyrrole unit without the protection of β‐position. The removal of 2‐pyrimidinyl substituent on the pyrrole unit proceeds efficiently and results in the enhancement of coplanarity along the main chain of the polymer.
The catalytic properties of bis(phenoxy‐imine) Zr and Hf complexes incorporating perfluorophenyl groups with methylaluminoxane were investigated. The fluorinated complexes produced far higher‐molecular‐weight polyethylenes and ethylene/propylene copolymers with increased activities compared with the non‐fluorinated congeners. Moreover, the fluorinated complexes displayed a higher incorporation ability for propylene.
Summary: The interaction of a polymer bearing β‐cyclodextrin moieties (β‐CD polymer) with poly(acrylamide)s bearing aromatic side chains was investigated by viscometry to study the effect of collectivity (i.e., interactions at multi‐sites) in macromolecular recognition. The formation of inclusion complexes at multi‐sites caused a large difference in the size of interpolymer aggregates, even though the difference in association constants for complexation of native β‐CD with guest moieties was not very much large.
Conceptual illustration for interpolymer aggregates of β‐CD polymer with poly(acrylamide)s bearing naphthyl groups substituted on the (a) 1‐ and (b) 2‐positions (see Scheme 1 ). 相似文献
Novel positive thermosensitive microgels of poly(acrylamide–acrylic acid) with embedded gold nanoparticles have been synthesized and characterized by means of dynamic light scattering, UV‐vis spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy. These systems show temperature (upper critical solution temperature‐like volume phase transition) and optical responsiveness making them externally triggered systems.
Summary: A chitin‐xylan hybrid polysaccharide having β(1 → 4)‐linked alternating structure of N‐acetyl‐D ‐glucosamine and D ‐xylose was synthesized via chitinase‐catalyzed polymerization. An oxazoline derivative of D ‐xylosyl‐β(1 → 4)‐N‐acetyl‐D ‐glucosamine ( 1 ) was effectively polymerized by the catalysis of chitinase from Bacillus sp., giving rise to a water‐soluble chitin‐xylan hybrid polysaccharide ( 2 ) in good yields. Molecular weights ( ) of 2 reached 1 500, which corresponds to 8–10 saccharide units.
A chitin‐xylan hybrid polysaccharide ( 2 ) synthesized via chitinase‐catalyzed polymerization. 相似文献
Furan ring‐functionalized solid surfaces are achieved by the initiated chemical vapor deposition (iCVD) method, a solvent‐free process to form films under mild conditions. The polymerization of furfuryl methacrylate monomer is initiated by a resistively heated filament wire. The functionality of the furan group in the iCVD film enabled Diels–Alder chemistry with 4‐phenyl‐1,2,3‐triazolin‐3,5‐dione (N‐PTD).
Summary: A simple method to prepare surfactant‐free and solvent‐free semiconducting polymer particles by using an environmentally benign supercritical carbon dioxide (scCO2) process is reported. The process of the rapid expansion of supercritical solutions (RESS) is used to produce spherical particles of poly[2‐(3‐thienyl)acetyl 3,3,4,4,5,5,6,6,7,7,8,8,8‐tridecafluorooctanoate] (PSFTE), 50–500 nm in size, from 0.1–0.5 wt.‐% PSFTE solutions in CO2 at pre‐expansion temperatures of 40 °C and pre‐expansion pressures of 276 bar.
An FESEM image of PSFTE particles produced by the RESS process with CO2. 相似文献
Bifunctional surfaces are micropatterned using a self‐aligned, dual‐purpose lithographic mask and pairs of conformally deposited iCVD polymers. A first layer is deposited, then physically masked and etched in oxygen plasma. A second layer is deposited with the mask still in place. Lift‐off reveals the micropatterned surface. The thicknesses of the two layers are independently controlled so that the resultant surface displays both chemical and topographical contrast. The patterning scheme is independent of the polymers used and order of deposition. We use this scheme to create surfaces that spatially confine microcondensation, as well as chemical functionality. We also demonstrate microwells whose depth can be altered in response to a water stimulus.
Summary: Monodisperse carboxy polystyrene (PS) spheres were synthesized and utilized as an interface to increase the detection sensitivity of some biomolecules. The binding behavior of dacarbazine (DTIC), an anticancer drug, with DNA bases in the absence and presence of the PS spheres was investigated. The results indicated a remarkable effect of PS on the binding behavior of DTIC to DNA bases and significantly enhanced detection sensitivity for the relative biomolecular recognition.
Electrochemical detection of DTIC on a GCE surface in the absence and presence of polystyrene spheres. 相似文献
Summary: The vapor‐based synthesis and characterization of a reactive polymer, poly[(4‐formyl‐p‐xylylene)‐co‐(p‐xylylene)] ( 1 ), have been reported. The reactive polymer coating enables the immobilization of oligosaccharides via the chemoselective aldehyde‐hydrazide coupling reaction.
Grafted conjugated polyelectrolytes were synthesized for the first time and characterized. The polymers demonstrated properties of a convenient and efficient protocol for creating Hg2+ sensors. The unique character of the new material comes from an anionic counterion nature with no external cofactors, and imparts high selectivity and fast detection for mercury ion in a fluorescence probe. The concept may be potentially applied to create new sensors for monitoring other ions.
The polymerization using a high‐yielding addition reaction between electron‐rich alkynes and 7,7,8,8‐tetracyanoquinodimethane (TCNQ) derivatives is described. The bifunctional monomer containing two TCNQ moieties and the counter comonomer bearing two dialkylaniline (DAA)‐substituted alkynes are reacted in 1,2‐dichloroethane under mild heating conditions. At the high monomer concentrations, high molecular weight linear polymers are obtained, while the reaction at the low monomer concentrations produces a significant amount of the cyclic compounds. A clear relationship between the monomer concentration and the cyclic compound amount is demonstrated. The obtained polymers feature a sufficient thermal stability with the decomposition temperature exceeding 300 °C as well as strong charge‐transfer (CT) bands and redox activities ascribed to the produced donor–acceptor moieties. These features are also used to optimize the polymerization conditions and to estimate the chemical structures.
