Preparation of a Star Network PEG-based Gel Polymer Electrolyte and Its Application to Electrochromic Devices

A star network polymer with a pentaerythritol core linking four PEG-block polymeric arms was synthesized, and its corresponding gel polymer electrolyte based on lithium perchlorate and plasticizers EC/PC with the character being colorless and highly transparent has been also prepared. The polymer host was characterized and confirmed to be of a star network and an amorphous structure by FTIR, ^1H NMR and XRD studies. The polymer host hold good mechanical properties for pentaerythritol cross-linking. Maximum ionic conductivity of the prepared polymer electrolyte has reached 8.83 × 10 ^-4 S·cm^-1 at room temperature. Thermogravimetry （TG） of the polymer electrolyte showed that the thermal stability was up to at least 150 ℃. The gel polymer electrolyte was further evaluated in electrochromic devices fabricated by transparent PET-ITO and electrochromically active viologen derivative films, and its excellent performance promised the usage of the gel polymer electrolyte as ionic conductor material in electrochrornic devices.     

A temperature and pH double sensitive cholesteric polymer film from a photopolymerizable chiral hydrogen-bonded assembly

In this study, a novel H-bonded cholesteric polymer film responding to temperature and pH by changing the reflection color was fabricated. The H-bonded cholesteric polymer film was achieved by UV-photopolymerizing a cholesteric liquid crystal (Ch-LC) monomers mixture containing a photopolymerizable chiral H-bonded assembly (PCHA). The cholesteric polymer film based on PCHA can be thermally switched to reflect red color from the initial green/yellow color as temperature is increased, which is due to a change in helical pitch induced by the weakening of H-bonded interaction in the polymer film. Additionally, the selective reflection band (SRB) of the cholesteric polymer film in solution with pH > 7 showed an obvious red shift with increasing pH values. While the SRB of the cholesteric polymer film in solutions with pH = 7 and pH < 7 hardly changed. This pH sensitivity in solutions with pH > 7 could be explained by the breakage of H-bonds in the cholesteric polymer film and the structure changes induced by―OH and―K + ions in the alkaline solution. In contrast, it couldn’t happen in the neutral and acidic solutions. The cholesteric polymer film in this study can be used as optical/photonic papers, optical sensors and LCs displays, etc.     

Tailoring the liquid crystalline property via controlling the generation of dendronized polymers containing azobenzene mesogen

The first‐ and second‐generation dendronized polymers containing azobenzene mesogen were designed and successfully synthesized via free radical polymerization. The chemical structures of the monomers were confirmed by elemental analysis, ¹H NMR, and ¹³C NMR. The molecular characterizations of the polymers were performed with ¹H NMR and gel permeation chromatography. The phase structures and transition behaviors were studied using differential scanning calorimetry, polarized light microscopy, and small‐angle X‐ray scatter experiments. The experiment results revealed that the first‐generation dendronized polymer exhibited liquid crystalline behavior of the conventional side‐chain liquid crystalline polymer with azobenzene mesogen, that is, the polymer exhibited smectic phase structure at lower temperature and nematic phase structure at higher temperature. However, the second‐generation dendronized polymers exhibited more versatile intriguing liquid crystalline structures, namely smectic phase structure at lower temperature and columnar nematic phase structure at higher temperature, and moreover, the phase structure still remained before the decomposition temperature. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1149–1159, 2010     

Poly[(4-N-ethylene-N-ethylamino)-α-cyanocinnamate]: A nonlinear optical polymer with a chromophoric mainchain. I. Synthesis and spectral characterization

Poly[(4-N-ethylene-N-ethylamino)-α-cyanocinnamate] was prepared by solution esterification of (4-N-ethyl-N-(2-hydroxyethyl) amino)-α-Cyanocinnamic acid and by melt transesterification of ethyl (4-N-ethyl-N-(2-hydroxyethyl) amino)-α-cyanocinnamate. The melt transesterification generally yielded polymer with a number-average molecular weight of about 10,200 by gel permeation chromatography (GPC) versus polystyrene standards. The polymer was found to be amorphous with a glass transition temperature of about 103°C by differential scanning calorimetry (DSC). The solution esterification generally gave a polymer with a number-average molecular weight of about 2200 by GPC versus polystyrene standards. This polymer was found to have a glass transition temperature varying between 60 and 90°C by DSC. The infrared (IR) spectrum of the polymer made from both methods were analyzed in detail. The ¹H- and ¹³C-NMR spectra of the meltsynthesized ethyl cinnamate derivative polymer are consistent with the reported structure.     

Synthesis and properties of new crystalline poly(arylene ether nitriles)

Crystalline poly(arylene ether nitrile) could be prepared by the polycondensation of 2,6-dihalobenzonitrile with resorcinol at 200°C in N-methylpyrrolidone in the presence of sodium carbonate. A reaction temperature of at least 200°C was necessary to attain high molecular weight polymer. Spectral data indicated that the polymer had the structure of a poly(meta-phenylene ether) with pendent nitrile groups on every other phenylene unit. Despite this structure, the crystallinity and the crystallization rate of the polymer were greater than those of the corresponding polymer with a para-linked structure. The glass transition temperature and the melting temperature of the polymer were almost the same as those of poly(etheretherketone) (PEEK^TM). A series of other new poly(arylene ether nitriles) were also examined. The polymers derived from 4,4′-biphenol, dihydroxytetra-phenylmethane, dihydroxydiphenylsulfone, and 1,5-isoquinolinediol had high glass transition temperatures. The poly(arylene ether nitriles) exhibited excellent tensile strength compared with the corresponding ketone- or sulfone-containing polymers. Comparing the three different kinds of polymers containing the same bisphenol units, the order of glass transition temperature was found to be sulfone- > nitrile- > ketone-containing polymers, while the order of tensile strength was nitrile- > ketone- > sulfone-containing polymers. The excellent mechanical properties are attributable to dipole-dipole interactions of nitrile groups. © 1993 John Wiley & Sons, Inc.     

The molecular-topological structure and thermal stability of Ftorplast F-2M polyvinylidene fluoride irradiated with 1-MeV protons

Pelletized polyvinylidene fluoride (PVDF) of the Ftorplast F-2M brand is a semicrystalline diblock polymer, and its topological structure remains almost unchanged after bombardment with 5 × 10¹⁴ proton/cm². The glass transition temperature of the irradiated polymer is reduced by 2°C, but the melting point of the crystalline polymorph and the flow temperature of the polymer significantly increase (from 35 to 137°C and from 132 to 151°C, respectively); the mass fraction of the crystalline modification also increases (from 0.12 to 0.70). As a result of fluorine abstraction by fast protons to form HF, the fluorine content of the polymer decreases and the carbon content increases. The irradiation has no substantial effect on the onset temperature of intense gas evolution or the composition of the gas released during heating the polymer to 300°C.     

Effect of NiO nanofiller concentration on the properties of PEO-NiO-LiClO4 composite polymer electrolyte

Composite polymer electrolyte films comprising polyethylene oxide (PEO) as the polymer host, LiClO₄ as the dopant, and NiO nanoparticle as the inorganic filler was prepared by solution casting technique. NiO inorganic filler was synthesized via sol-gel method. The effect of NiO filler on the ionic conductivity, structure, and morphology of PEO-LiClO₄-based composite polymer electrolyte was investigated by AC impedance spectroscopy, X-ray diffraction, and scanning electron microscopy, respectively. It was observed that the conductivity of the electrolyte increases with NiO concentration. The highest room temperature conductivity of the electrolyte was 7.4?×?10^?4 S cm^?1 at 10 wt.% NiO. The observation on structure shows the highest conductivity appears in amorphous phase. This result has been supported by surface morphology analysis showing that the NiO filler are well distributed in the samples. As a conclusion, the addition of NiO nanofiller improves the conductivity of PEO-LiClO₄ composite polymer electrolyte.     

Synthesis and use of α-methoxyphenylmethylium hexachloroantimonate as a novel initiator for the polymerization of propylene oxide

α-Methoxyphenylmethylium hexachloroantimonate was prepared from α-methoxybenzyl chloride and antimony pentachloride at 0°C and isolated for the first time, and its visible and ¹H-NMR spectra were measured. This salt was used as a novel initiator for the polymerization of propylene oxide (PO) in the temperature range ?20 to 30°C with dichloromethane as solvent. PO polymerized spontaneously but a limit yield was observed. The microstructure of PO polymer is amorphous by ¹³C-NMR. The PO polymerization is thought to proceed in the conventional cationic mechanism on the basis of the polymerization behavior and the analyses of both the polymer structure and end groups attached to the PO polymer.     

Role of the polymer microstructure in the thermoreversible gelation of poly(vinyl chloride)

Gels of polyvinylchloride (PVC) and PVC copolymers of different microstructure and molar composition, were prepared in a series of diester-like solvents. The viscoelastic properties of these gels were evaluated as a function of temperature and the molecular structure was studied by small-angle neutron scattering. The degrees of proton association in the polymer solutions were determined by ¹H NMR spectroscopy by measuring the intensity of proton bands of CH₂ monomeric units. The body of experimental data shows clearly that there is a straight relation between molecular structure, viscoelastic properties of the gel, degree of polymer-solvent interaction and polymer microstructure.     

Effect of bombardment with helium ions on the molecular-topological structure and elemental composition of the surface of polytetrafluoroethylene

Irradiation of a polytetrafluoroethylene (PTFE) film with accelerated (1–5 MeV) helium ions at a fluence of 10¹⁵ ion/cm² has been studied. The efficiency of carbonization, defined as a decrease in the fluorine content and an increase in the carbon content on the surface of the polymer, increases with the incident ion energy. A characteristic feature of the topological structure of PTFE is the presence of four high-meltingpoint crystalline modifications, the “branching points” of the pseudo-network of the amorphous matrix block, in addition to a low-melting-point modification with the melting onset temperature of 13°C. After bombardment with 3–5 MeV ions, only two crystalline blocks remain in the polymer and a cluster block, which was not present in the unirradiated polymer, appears. The overall mass fraction of the crystalline structure in the irradiated polymer (0.48) is below that in the initial polymer (0.66), indicating amorphization of its structure.     

A novel positively thermo-sensitive hydrogel based on ethylenediaminetetraacetic dianhydride and piperazine: Design, synthesis and characterization

A new positively thermo-sensitive hydrogel was designed and synthesized by a condensation polymerization reaction of ethylenediaminetetraacetic dianhydride（EDTAD） and piperazine（PA） to give poly（ethylenediaminetetraacetic dianhydride-copiperazine） （PEP）.The obtained polymers’ structure was characterized by FTIR and ¹³C NMR.The backbone of the polymer linked by amide bond and abundant of carboxyl groups as pendant group could form strong intermolecular and intramolecular hydrogen bond at lower temperature and dissociate at higher temperature,resulting in the polymer with thermo-sensitivity.The aqueous solution of PEP at lower temperature（<20℃） showed micro-gel formation and transformed to transparent solution at higher temperature（>40℃）.Transition temperature shifted to higher value with the increasing of concentration.The hydrogel exhibited reversible phase transition and the transmittance change was not weakened by multiple temperature changes.     

Poly(imino imino ether ether ketone ketone) as novel soluble heat-resistant polymer

In this paper, we introduce a novel high-performance polymer, poly(imino imino ether ether ketone ketone), which has been synthesized by the palladium-catalyzed C-N cross coupling reaction of 1,4-bis-(4-bromobenzoyl) benzene and 1,3-bis-(4-aminophenoxy) benzene. The structure of the polymer is characterized by means of ¹H NMR spectroscopy and elemental analysis, and the results show a good agreement with the proposed structure. Compared with traditional poly(ether ether ketone)s, the solubility of the synthesized polymer in common organic solvents was higher; it also exhibited high glass transition temperature (T _g = 176°C) and good thermal stability with high decomposition temperature (T ₅ = 400°C).     

Cross-linking copolymers of acrylates’ gel electrolytes with high conductivity for lithium-ion batteries

The cross-linking gel copolymer electrolytes containing alkyl acrylates, triethylene glycol dimethacrylate, and liquid electrolyte were prepared by in situ thermal polymerization. The gel polymer electrolytes containing 15 wt% polymer content and 85 wt% liquid electrolyte content with sufficient mechanical strength showed the high ionic conductivity around 5?×?10^?3 Scm^?1 at room temperature. The gel electrolytes containing different polymer matrices were prepared, and their physical observation and conductivity were discussed carefully. The cross-linking copolymer gel electrolytes of alkyl acrylates with other monomers were designed and synthesized. The results showed that copolymerization can improve the mechanical properties and ionic conductivities of the gel electrolytes. The polymer matrices of gels had excellent thermal stability and electrochemical stability. The scanning electron microscope analysis showed the gel electrolyte was the homogeneous structure, and the cross-linking polymer host was the porous three-dimensional network structure, which demonstrated the high conductivity of the gel electrolytes. The gel polymer Li-ion battery was prepared by this in situ thermal polymerization. The cell exhibited high charge-discharge efficiency at 0.1 C. The results of LiFePO4-PEA-Li cell and graphite-PEA-Li cell showed that gel polymer electrolytes have good compatibility with the battery electrodes materials.     

Synthesis of a novel poly[2]-catenane containing rigid catenanes

A novel poly[2]-catenane containing rigid catenane subunits connected by semirigid spacers has been synthesized. This new macromolecular architecture is the second example of a polymer containing topological bonds in the main chain. The poly[2]-catenane structure was proved by spectroscopic methods, especially ¹H NMR, IR and MALDITOF. The polymer is thermally stable up to 380°C and shows a high glass transition temperature of ca. 265°C.     

Structure and properties of poly-2,5-distyrylpyrazine

Poly-2,5-distyrylpyrazine (poly-DSP) was investigated by differential thermal analysis (DTA), thermogravimetric analysis (TGA), and measurements of dynamic viscoelastic and electrical properties. From DTA and TGA studies it was confirmed that poly-DSP melts at 321°C and depolymerizes rapidly to the monomer at temperatures between 335°C and 345°C in helium. The polymer is affected by oxygen above 200°C. The E′ value from dynamic viscoelasticity measurements on amorphous film is 2 × 10¹¹ dyne/cm² at room temperature. It decrease abruptly in the temperature range 140–150°C; but the net decrease of E′ within this temperature range is relatively small. The electrical properties of amorphous poly-DSP are characterized by a small temperature dependence of the dielectric constant between room temperature and 100°C. The dielectric loss tangent was observed to be small, and the dc conductivity was extremely small. It is concluded that rotation of the phenyl branches in the polymer occurs above ?30°C and the glass transition occurs at about 150°C. These properties are discussed in some detail in relation to the polymer structure.     

Infrared study of polymorphism of tert-butanol

Infrared absorption spectra of tert-butanol-OH, -OD and mixed crystals were measured in the temperature range of 96–305 K and the frequency range of 400–3600 cm^′-1. Two solid phases I and II were identified. The interpretation based on the C_2v chain polymer and D⁹_2h crystal structure was found to be appropriate for phase II. Experimental arguments in favour of a C_3h cyclic polymer structure of phase I were given.     

通过自缩合乙烯基氧阴离子聚合制备超支化聚甲基丙烯酸羟丙酯

由甲基丙烯酸羟丙酯通过自缩合乙烯基氧阴离子聚合(self-condensing vinyl oxyanionic polymerization)制备了端羟基的超支化聚甲基丙烯酸酯. 以氢化钾(KH)和冠醚的复合物为引发剂时, 可以得到高分子量的聚合物. 用¹H NMR和¹³C NMR谱图证实了聚合物的超支化结构. 由于在聚合过程中存在质子转移反应, 引发剂与单体的摩尔比会影响所得聚合物的结构. 超支化聚合物的玻璃化转变温度在58.1～81.4 ℃之间, 且随着引发剂与单体的比例的减小而降低. 当引发剂与单体等摩尔比时, 所得聚合物的支化度为0.49.     

Synthesis,thermo-responsive micellization and caffeine drug release of novel PBMA-<Emphasis Type="Italic">b</Emphasis>-PNIPAAm block polymer brushes

Brush-like block copolymers with poly(t-butyl methacrylate) (PBMA) and poly(N-isopropylacrylamide) (PNIPAAm) as side arms, PBMA-b-PNIPAAm, were designed and synthesized via a simple free radical polymerization route. The chemical structure and molecular weight of these polymer brushes were characterized and determined by nuclear magnetic resonance (¹H NMR), Fourier transform infrared spectrometry (FTIR) and gel permeation chromatography (GPC). The micellar formation by these polymer brushes in aqueous solutions were detected by a surface tension technique, and the critical micelle concentration (CMC) ranged from 1.53 to 8.06 mg L⁻¹. The morphology and geometry of polymer micelles were investigated by transmission electron microscope (TEM) and dynamic light scattering (DLS). The polymer micelles assume the regularly-spherical core-shell structure with well-dispersed individual nanoparticles, and the particle size was in the range from 36 to 93 nm. The PNIPAAm segments exhibited a thermoreversible phase transition, so the resulting block polymer brushes were temperature-sensitive and the low critical solution temperature (LCST) was determined by UV-vis spectrometer at about 28.82–29.40°C. The characteristic parameters of the polymer micelles such as CMC, micellar size and LCST values were affected by their compositional ratios and the length of hydrophilic or hydrophobic chains. The evaluation for caffeine drug release behavior of the block polymer micelles demonstrated that the self-assembled micelles exhibited thermal-triggered properties in controlled drug release.     

Synthesis and magnetic properties of complexes of a conjugated hyperbranched polymer containing bithiazole rings

A novel conjugated hyperbranched polymer containing bithiazole rings（PBTADB） was synthesized by polycondensation of 1,3,5-benzenetricarboxaldehyde and 2,2’-diamino-4,4’-bithiazole（DABT）.The structure of the hyperbranched polymer was confirmed by FT-IR and ¹H-NMR.PBTADB dissolved in organic polar solvents such as DMSO and NMP.Bithiazole rings were introduced to provide bidentate N-donor sites for binding metal ions.The metal complexes were prepared by chelation of the polymer with Co²⁺ and Sm³⁺.The magnetic behavior of coordination compounds was measured as a function of magnetic field strength（0-4.8×10⁶ A/m） at 5 K and as a function of temperature（5-300 K） at magnetic field strength of 2.4×10⁶ A/m.The magnetic hysteresis loops of PBTADB-Sm³⁺and PBTADB-Co²⁺showed the typical ’S’ shape at 5 K with the Curie-Weiss temperature T_θ=96 K and 41 K respectively.The results show that they exhibit properties of soft ferromagnetic materials.     

Sorption and catalytic effects upon the dehydration of methanol on perfluorinated copolymer-containing sulfo groups

The peculiarities of methanol transformation on the surface of perfluorinated copolymer, fluoroplastic, containing sulfo groups were studied. At temperatures of 70–120°C, the polymer was established to have high initial activity during the conversion of methanol into dimethyl ether; this reaction was, however, accompanied by strong water sorption that leads to a rapid drop in the activity. The sorption/desorption processes were characterized by temperature effects such as heating during sorption and cooling during desorption. The structure of the polymer in the salt (sodium cations) and acid (hydrolyzed polymer) forms was studied by IR spectroscopy. H₃O⁺SO₃⁻ ionic pairs were found to be present in the acid form.