Complexation of Syndiotactic Polystyrene with 12‐Crown‐4

Solid‐state complexation of syndiotactic polystyrene (sPS) with a crown ether compound, 1,4,7,10‐tetraoxa‐cyclododecane (12‐crown‐4), took place when a film of sPS/chloroform clathrate was subjected to a guest exchange procedure assisted with a plasticizing agent. The new guest 12‐crown‐4 molecules were incorporated into the crystalline region of the sPS film, without causing a large conformational change of host sPS helices. X‐ray diffraction and thermogravimetric investigations showed that sPS/12‐crown‐4 complex had a clathrate complex structure which contained four 12‐crown‐4 molecules per unit cell. IR and Raman data suggested that 12‐crown‐4 took a C_i‐type conformation in the sPS complex phase.

     

Selective Guest Uptake from Solvent Mixtures in the Clathrate Phase of Syndiotactic Polystyrene

Summary: Selective absorption uptake during the guest‐exchange processes in the δ form of syndiotactic polystyrene (sPS) was confirmed by IR spectroscopy. When films of the δ form were immersed in hexane/decane or chloroform/decane mixtures, decane molecules were incorporated preferentially in the δ form. Sorbate uptake by the δ form was greatly accelerated when the sorbate was mixed with a solvent penetrable to the amorphous region of sPS.

Concentration changes in a δ‐form film during sorption processes: sorption of a chloroform(D)/decane(H) mixture (1:1 molar ratio).     

Ethylene‐Norbornene Copolymerization by New Titanium Complexes Bearing Tridentate Ligands. Sidearm Effects on Catalytic Activity

The Ti complexes containing tridentate [O⁻NS^R] (R = Me, ⁱPr) ligands with alkylthio sidearms were prepared. The methylthio ether complex (R = Me shown in the Scheme) exhibits an excellent activity for copolymerization of ethylene with norbornene upon activation with MMAO, which is 10 times more active than the corresponding phenylthio one (R = Ph).

     

Isobutene Polymerization Using [CuII(NCMe)6]2+ with Non‐Coordinating Anions as Catalysts

Cu^II compounds coordinated octahedrally with nitriles and associated with bulky, non‐coordinating counter ions can be applied in the polymerization of isobutene at 30 °C. High yields and a high content of terminal double bonds are reached in the resulting highly reactive polyisobutylenes, while the molecular masses are moderate. Two of the coordinating nitriles are more weakly coordinated than the other four, as can be concluded from an exemplary X‐ray structure and from vibrational spectra, thus providing easily accessible sites for substrate coordination.

     

Synthesis of POSS‐Functionalized Polyisobutylene via Direct Initiation

POSS‐functionalized polyisobutylenes (PIBs) were synthesized by carbocationic polymerization using an epoxy‐POSS/TiCl₄ initiating system in hexane/methyl chloride (60:40 v/v) solvent mixture at −80 °C. ¹H NMR spectroscopy verified the incorporation of one epoxy‐POSS per polymer chain. Light scattering and TEM analysis demonstrated the formation of 50–100 nm sized aggregates and micron‐sized clusters.

     

Synthesis and Evaluation of Novel Proton Exchange Membranes Containing the Semisquaric Acid Group

We focus our attention here on semisquaric acid, which is known to show high acidity, as a new proton dissociating group for proton exchange membranes (PEMs). The introduction of a squaric acid group into aromatic polymers was conducted by the reaction of lithiated aromatic polymers and diisopropoxy squarate, followed by treatment with hydrochloric acid. A resulting polyphenylsulfone membrane with the squaric acid group introduced (PPSf‐SQ, IEC = 4.1 meq·g⁻¹) showed proton conductivity of 1.0 × 10⁻¹ S·cm⁻¹ at 80 °C under 95% relative humidity, which indicates that the semisquaric acid has the potential to become an alternative proton‐conducting group for PEMs.

     

Cu Crystal Growth on a Chelating Fiber with Different Amine Chain Lengths

Summary: Poly(acryloamidino ethyleneamine) (PAEA) and poly(acryloamidino diethylene diamine) (PADD) have been synthesized for the observation of Cu^II complex and Cu(OH)₂ crystal‐growth on the surface of different numbers of amino groups immobilized on polyacrylonitrile (PAN) fibers. The shape of Cu^II crystal growth depends on the amine chain length of the chelating fiber; Cu(OH)₂ crystals grow on the surface of the chelating fiber after Cu^II adsorption.

     

Template‐Assisted Synthesis of Self‐Doped Polyaniline: Morphological Effects of Templates on the Conductivity

Self‐doped sulfonated polyaniline (PSA) has been synthesized on the surface of micellar nanoparticles made from positively charged surfactants by biocatalysis. The conformation forced by the electrostatic charge interactions between the positively charged micelle and the negatively charged PSA increases the conductivity of the PSA by three orders of magnitude. The pure PSA recovered from ion exchange, however, shows quite similar electrical properties compared with sulfonated polyanilines reported earlier. The increased conductivity of PSA complexes is as a result of the increased charge carrier concentration caused by a certain conformational locking.

     

Transparent Nonlinear Optical Polymers for All‐Optical Wavelength Converters in Optical Fiber Communications

After synthesizing two chromophores with imine, we prepared acrylic nonlinear optical (NLO) polymers that contained the chromophores for all‐optical wavelength converters in optical fiber communication. The polymers show high d₃₃, 35 pm · V⁻¹, at 1.55 μm (pumping beam), considering their low losses, −3.0 dB · cm⁻¹, at a wavelength of 0.785 μm (near second harmonic signal beam of the pumping beam). This result means that the polymers are good candidates for wavelength converters of an approximately 1.55 μm signal beam.

UV‐vis spectra of NLO chromophores and polymers.     

Self‐Complementary Nucleoside‐Thiophene Hybrid Systems: Synthesis and Supramolecular Organization

Versatile synthetic methods towards a variety of thiophene‐nucleobase hybrid systems are reported. Adenine‐ and thymine‐based modified nucleosides characterized by a bithiophene unit linked to the C5′ or C8 position through an ethylenamino or an ethylensulfanyl bridge were synthesized and successfully polymerized in the presence of FeCl₃. The self‐organization properties of the pure polymers as well as their mixtures ‐ with complementary nucleobases ‐ were investigated by means of optical microscopy and AFM in cast film showing complex supramolecular structures resulting from the interplay of multiple intermolecular interactions.

     

Carbon Nanotubes as a Ligand in Cp2ZrCl2‐Based Ethylene Polymerization

Summary: We report a simple method for tuning catalytic property of a metallocene‐based catalyst, Cp₂ZrCl₂, for ethylene polymerization by the direct adsorption of Cp₂ZrCl₂ onto multi‐walled carbon nanotubes (MWCNTs). The direct interactions between MWCNTs and the Cp rings of Cp₂ZrCl₂ controlled the polymerization behaviors, and we could generate polyethylene with an extremely high molecular weight ( = 1 000 000) at 30 °C and under 1 atm of ethylene gas.

Preparation of Cp₂ZrCl₂‐MWCNT.     

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⁺.

     

Preparation of the Ultra‐Low Dielectric Constant Polyimide Fiber Membranes Enabled by Electrospinning

In this article, electrospinning technique has been demonstrated for the synthesis of ultra‐low dielectric constant polyimide fiber membranes. Poly(amic acid) fiber membranes have been prepared as precursor. After the treatment of thermal imidization, ultra‐low dielectric constant polyimide fibers membranes can be obtained. The morphologies and structures of precursors and products are characterized by scanning electron microscopy (SEM), Fourier transmission infrared (FTIR) spectra, and a radio frequency (RF) impedance/capacitance material analyzer. The DK of the as‐prepared polyimide membrane ranges from 1.53 to 1.56, which could be applied in the electronic packaging industry.

     

Novel Biopolymer Matrices for Microencapsulation of Phages: Enhanced Protection Against Acidity and Protease Activity

Phage therapy by oral administration requires enhanced resistance of phages to the harsh gastric conditions. The aim of this work is the microencapsulation of phages in natural biopolymeric matrices as a protective barrier against the gastric environment. Alginate and pectin are used as base polymers. Further emulsification with oleic acid or coating with a different biopolymer is also studied. Emulsified pectin shows the maximum encapsulation efficiency and the highest protection against acidity, leaving more than 10³ active phages after 30 min exposure at pH = 1.6, and protects phage from pepsin activity (4.2 mg mL^?1). Non‐encapsulated phages are fully inactivated at pH = 1.6 or with pepsin (0.5 mg mL^?1) after 10 min.

     

Mono‐, Di‐, or Triazidated Cyclodextrin‐Based Polyrotaxanes for Facile and Efficient Functionalization via Click Chemistry

As a feasible way for controlling the density of ligands in polyrotaxanes, azidated polyrotaxanes comprising PEG (MW = 3 000 and 20 000 g · mol⁻¹) and mono‐, di‐, or triazidated α‐cyclodextrins are prepared in a water/DMSO solution in a one‐pot synthesis. The azidated polyrotaxanes are then allowed to conjugate with propargyl‐modified mannose as a ligand via click chemistry. As proven by FTIR spectroscopy and ¹H NMR‐spectroscopy, mannose molecules are efficiently introduced into all of the azide moieties of the polyrotaxanes. The results verify the achievement of ligand‐density‐controlled polyrotaxanes. The functionalized polyrotaxanes can be utilized for a variety of biological applications.