One‐Step Preparation of Electrospun Microfibrous Polystyrene Mats Having Surface Enriched in p‐tert‐Butylcalix[4]arene Fitted with Phosphinoyl Pendant Arms

Polystyrene microfibers containing lower‐rim substituted calix[4]arene with phosphinoyl pendant arms were easily prepared in one‐step procedure by electrospinning. A specific feature of the fibers is the difference in their functionality at the surface and in the bulk. The graded structure of the fibers was shown by XPS analyses. The calix[4]arene concentration in the 3–5 nm surface layer was 50% higher than the theoretically calculated if calix[4]arene was uniformly distributed in the fibers. A six‐coordinated complex was formed between the calix[4]arene included in the fibers and Ni²⁺ ions. The distribution of phosphorus along the fibers is uniform, as evidenced by X‐ray mapping.

     

Thermosensitive and Switchable Terpyridine‐Functionalized Metallo‐Supramolecular Poly(N‐isopropylacrylamide)

Metallo‐supramolecular polymers offer attractive possibilities to combine the properties of polymers with the characteristics offered by the metal–ligand coordination. Here we present for the first time the combination of metal‐bis(terpyridine) complexes and lower critical solution temperature (LCST) polymers that can be switched by addressing either the thermosensitive polymer or the metal complex. We describe a new strategy for the synthesis of poly(N‐isopropylacrylamide) (PNIPAM) end functionalized with a terpyridine moiety, which is further used for the preparation of Fe^II and Zn^II‐bis(terpyridine PNIPAM). The comparison of the LCST behavior of the uncomplexed ligands and their metal complexes that bear different counter ions is included. Furthermore, the switchability of the synthesized Fe^II system is demonstrated by a decomplexation reaction followed by the characterization of the uncomplexed ligand.

     

A New Class of Blue‐Emitting Materials for LED Applications: Triarylamine N‐Functionalised 2,7‐Linked Carbazole Polymers

Attachment of triarylamino‐functional groups at the 9‐position of 2,7‐linked carbazole polymers results in blue‐emitting materials with two independent redox processes that were attributed to the triarylamino groups and the polymer backbone, respectively. This new class of blue‐emitting conjugated polymers was prepared via a Suzuki cross‐coupling reaction and showed low turn‐on voltages in electroluminescent devices as a result of their low ionisation potentials. The photophysical, electrochemical and electroluminescent properties of these materials are discussed.

     

Self‐Assembled,Thermosensitive PCL‐g‐P(NIPAAm‐co‐HEMA) Micelles for Drug Delivery

Summary: A novel thermosensitive amphiphilic copolymer (PCL‐g‐P(NIPAAm‐co‐HEMA)) comprised of hydrophobic PCL segments and hydrophilic P(NIPAAm‐co‐HEMA) segments was designed and synthesized. The structure of the copolymer was characterized by FT‐IR, ¹H NMR and GPC analysis. The copolymer may self‐assemble into micelles in water and the resulting micelles demonstrated temperature sensitivity with a lower critical solution temperature (LCST) of 33 °C. The critical micellar concentration (CMC) obtained from surface tension measurements and the fluorescence method was around 30 mg · L⁻¹. Transmission electron microscopy (TEM) showed that the micelles exhibit a nanospheric morphology within a narrow size range of 150–160 nm. A cytotoxicity study showed that the PCL‐g‐P(NIPAAm‐co‐HEMA) copolymer exhibits good biocompatibility. The controlled drug release of the resulting micelles was investigated and it was found that micelles loaded with prednisone acetate showed improved drug release behavior due to the special micellar structure.

Self‐assembly of the PCL‐g‐P(NIPAAm‐co‐HEMA) copolymers.     

Comprehensive Triblock Copolymer Analysis by Coupled Thermal Field‐Flow Fractionation‐NMR

Thermal field‐flow fractionation (ThFFF) is used as a novel fractionation technique to investigate the molecular heterogeneity of PB‐b‐PVP‐b‐PtBMA triblock copolymers. Such copolymers cause major problems in liquid chromatography due to very strong polar interactions with the stationary phase. ThFFF separates the copolymers with regard to size and/or chemical composition based on the normal and thermal diffusion coefficients. The separation mechanism in ThFFF and the chemical composition of the separated species is elucidated by online ¹H NMR. Based on the compositional analysis and a calibration of the system with the respective homopolymers, the samples are quantified regarding their molar masses, chemical compositions, and microstructures providing comprehensive information on the complex structure of these block copolymers.

     

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.

     

Synthesis of Comb Tri‐ and Tetrablock Copolymers Catalyzed by the Grubbs First Generation Catalyst

High molecular weight tri‐ and tetrablock copolymers were synthesized from the commercially available Grubbs first generation catalyst for the first time. These polymers had degrees of polymerization from 430 to 1 100, molecular weights up to 419 000 g · mol⁻¹, and narrow polydispersities. Oxanorbornene monomers were chosen due to their fast rates of polymerization and slow rates of cross metathesis. Polystyrene arms were grown from selected blocks by atom transfer radical polymerization to yield architecturally complex comb tri‐ and tetrablock copolymers. These polymers self‐assembled in the solid state into ordered morphologies that were characterized by scanning electron microscopy.

     

Multi‐Morphological Complex Aggregates Formed from Amphiphilic Poly(ethylene oxide)‐block‐Polydimethylsiloxane‐block‐Poly(ethylene oxide) Triblock Copolymers

Summary: Amphiphilic triblock copolymers (PEO_x‐b‐PDMS_y‐b‐PEO_x) with different block lengths were synthesized and multi‐morphological complex crew‐cut, star‐like, and short‐chain aggregates were prepared by self‐assembly of the given copolymers. The morphologies and dimensions of the aggregates can be well controlled by variation of the preparation conditions. TEM, SEM, FFR‐TEM, and LLS studies show the resulting morphologies range from LCMs, unilamellar or multilayer vesicles, LCVs, porous spheres to nanorods.

TEM images of the vesicles formed from PEO‐b‐PDMS‐b‐PEO.     

Synthesis and Characterization of Chitosan Grafted Oligo(L‐lactic acid)

Chitosan grafted oligo(L ‐lactic acid) copolymers with different length of side chain were prepared through the reaction of terminal aldehyde group of oligo(L ‐lactic acid) (OLLA) and amino groups of chitosan. The mean molecular mass of the grafting OLLA chain was ca. 600 ～ 5 000. The graft copolymers are soluble in DMSO, DMF and acetic acid. The synthesis method and structure described here provide chitosan‐g‐OLLA copolymers with broad applicability.

Structure of chitosan‐g‐oligo(L ‐lactic acid).     

Synthesis and Self‐Assembly of Amphiphilic Diblock Copolymers using a Fluorescently Labeled N‐Alkoxyamine Initiator

Summary: An initiator for nitroxide mediated ‘living’ free radical polymerization was prepared with a fluorescent tag attached to the initiating alkyl radical terminus. This was used to synthesize amphiphilic poly(acrylic acid)‐block‐polystyrene diblock copolymers, which self assembled in a tetrahydrofuran/buffer solution to form structures that are visible by fluorescence.

     

Catalytic Polymerizations of Hydrophobic,Substituted, Acetylene Monomers in an Aqueous Medium by Using a Monomer/Hydroxypropyl‐β‐cyclodextrin Inclusion Complex

Ten hydrophobic, substituted, acetylene monomers were examined as to their abilities to form an inclusion complex with hydroxypropyl‐β‐cyclodextrin (HPCD). Only the monomers with suitable substitutents were found to form the monomer/HPCD complex, which was identified by NMR, FTIR, and UV‐vis spectroscopy. Polymerizations of the monomers were successfully carried out in aqueous solution by using the prepared monomer/HPCD inclusion complex and by using a water‐soluble Rh‐based catalyst, [Rh(cod)₂BF₄] or [Rh(nbd)(H₂O)OTs]. Such polymerizations provided high‐yield (>90%) polymers with a cis content of approximately 100%. The as‐prepared polymers could take an ordered helical conformation, just like their counterparts obtained in organic solvents.

     

Novel Biodegradable Copolymers with a Periodic Sequence Structure Derived from Succinate Butan‐1,4‐diol,and Butan‐1,4‐diamine

Summary: Novel biodegradable copolymers derived from succinate, butan‐1,4‐diol, and butan‐1,4‐diamine were synthesized by two‐step polycondensation reactions. The obtained copolymers had a periodical‐sequence structure consisting of ester and amide units, and the melting temperatures of the periodic copolymers increased with an increase in amide content. The crystalline structure of the periodic copolymers differs from that of butylene succinate homopolymer (PBS), and these results suggest that the periodically introduced amide units are included in the crystalline phase forming a novel crystalline structure.

Periodic copolyester‐amides derived from succinate, butane‐1,4‐diol, and butan‐1,4‐diamine     

Porphyrinated Nanofibers via Copolymerization and Electrospinning

Summary: The first example of the synthesis of acrylonitrile copolymers with porphyrin pendants and the subsequent electrospinning of the resultant copolymers into nanofibers is presented in this communication. Vinyl porphyrin monomers have been synthesized and copolymerized with acrylonitrile through solution polymerization. FT‐IR, NMR, UV‐vis, and fluorescence spectroscopy are used to characterize the copolymers. Preliminary quantum chemical calculations have also been carried out to reveal the activity of the vinyl porphyrin monomers. Nanofibers with a diameter of around 330 nm are prepared by electrospinning the copolymer solutions. Their morphology and porphyrination are clearly observed by field‐emission scanning electron microscopy and fluorescence microscopy. It is speculated that this type of nanofiber may be a latent support of porphyrins for various purposes such as catalysis, molecular imprinting, sensors, and light/energy conversion.

The formation of luminescent nanofibers from porphyrinated polymers.     

A Catalytic Approach to Functional Poly(1,4‐ketone)s Bearing Pendant Monosaccharide Fragments

Summary: Novel alternating polyketone‐based polymers bearing pendant saccharide units that are accessible by polymerization catalysis are presented. The materials were synthesized by polymerization of carbon monoxide and α‐olefins containing protected glucose or N‐acetyl glucosamine residues. The dicationic Pd^II bis(phoshine) complex [Pd(dppp)(NCCH₃)₂](BF₄)₂ was used as a catalyst precursor. An O‐deacetylation of the copolymers afforded materials with amphiphilic character.

Structure of the poly(1,4‐ketone) copolymers synthesized here.     

Modeling of Network Formation in Nitroxide‐Mediated Radical Copolymerization of Vinyl/Divinyl Monomers Using a Multifunctional Polymer Molecule Approach

A mathematical model for the kinetics of copolymerization with crosslinking of vinyl/divinyl monomers in the presence of stable nitroxyl radicals is presented. A reaction scheme considering multifunctional polymer molecules is proposed. The Flory‐Stockmayer theory is used for the post‐gelation period. Average crosslink and cyclization densities are calculated using two different approaches. Good agreement between predicted profiles and experimental data from our and other groups is observed in all cases. Overall monomer concentration, controller/initiator ratio, and crosslinker initial concentration are found to be the governing factors for the development of average crosslink and cyclization densities and therefore for the homogeneity of the resulting polymer network.

     

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.

     

New Strategy Targeting Well‐Defined Polymethylene‐block‐Polystyrene Copolymers: The Combination of Living Polymerization of Ylides and Atom Transfer Radical Polymerization

Well‐defined polymethylene‐block‐polystyrene (PM‐b‐PS) diblock copolymers were synthesized via a combination of living polymerization of ylides and atom transfer radical polymerization (ATRP) of styrene. A series of hydroxyl‐terminated polymethylenes (PM‐OHs) with different molecular weight and narrow molecular weight distribution were prepared using living polymerization of ylides following efficient oxidation in a quantitive functionality. Then, the macroinitiators (PM‐MIs ( = 1 900–15 000; PDI = 1.12–1.23)) transformed from PM‐OHs in ≈ 100% conversion initiated ATRPs of styrene to construct PM‐b‐PS copolymers. The GPC traces indicated the successful extension of PS segment ( of PM‐b‐PS = 5 000–41 800; PDI = 1.08–1.23). Such copolymers were characterized by ¹H NMR and DSC.

     

Multifunctional Poly(N‐vinylcarbazole)‐Based Block Copolymers and their Nanofabrication and Photosensitizing Properties

The synthesis of poly(N‐vinylcarbazole)‐based block copolymers functionalized with rhenium diimine complexes or pendant terpyridine ligands is reported. The copolymers are synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization, and they exhibit interesting morphological properties as a result of the phase separation between different blocks. The rhenium complex polymer block may function as a photosensitizer, while the terpyridine‐containing polymer block can be used as the template for nanofabrication by selective deposition of zinc complexes.

     

Sensing Behavior of Fluorescent Cyclodextrin/Peptide Hybrids Bearing a Macrocyclic Metal Complex

Two kinds of cyclodextrin/peptide (CD/peptide) hybrids bearing Zn^II‐cyclen or cyclen, dansyl and β‐cyclodextrin (β‐CD) units have been synthesized as chemosensors for organic anionic molecules. Zn^II‐cyclen serves as a ligand site and β‐CD is a receptor site for guest molecules, while the dansyl unit acts as a fluorescent probe. Examination of the fluorescence behaviors of these CD/peptides suggest that the hybrid containing Zn²⁺ has larger binding constants with respect to anionic molecules than that without Zn²⁺.

     

Synthesis and Characterization of a Novel Thermo‐Sensitive Copolymer of N‐Isopropylacrylamide and Dibenzo‐18‐crown‐6‐diacrylamide

Summary: A series of novel, thermo‐sensitive copolymers with different molar ratios of N‐isopropylacrylamide (NIPAM) and hydrophobic cis‐dibenzo‐18‐crown‐6‐diacrylamide (cis‐DBCAm) were prepared via free‐radical copolymerization. cis‐DBCAm with polymerizable end groups was successfully synthesized by reacting the corresponding amino crown ether with acryloyl chloride. The copolymers were characterized by FT‐IR and elemental analysis, and the thermo‐sensitivities of the copolymers were evaluated by measuring their lower critical solution temperatures (LCSTs) in the absence or presence of various metal ions. The results indicated that incorporation of cis‐DBCAm lowered LCSTs, and that the LCSTs of the copolymers decreased with the increase in cis‐DBCAm content in the copolymers. When the cavities of the crown ether units captured either K⁺ or Cs⁺ ions, the LCST of the respective copolymer–metal ion complex was further decreased, whereas the capture of Na⁺ or Li⁺ ions did not have a significant influence on the LCSTs of the copolymers.

Incorporation of cis‐DBCAm into PNIPAM resulted in a lower LCST. The LCST was decreased more when the cavities of the crown ether units captured K⁺ ions.