卟啉类L—B膜分子间相互作用的光谱研究

以无取代的meso-四-(4-N)-吡啶基卟啉及其过渡族金属(主要Cu~(2+)、Zn~(2+))络合物制备L-B膜,以近紫外-可见吸收光谱和荧光光谱为手段,研究叶啉类分子在氯仿溶液中,L-B膜状态下以及固态状态下的相互作用。探讨分子聚集体的存在对光谱性质的影响。 为了研究叶咻类分子间的相互作用及其对光谱性质的影响,我们首先分析了叶啉在CHCl_3溶液中及固态状态下的近紫外-可见吸收光谱和荧光光谱。并将其与叶啉类分子的L-B膜作比较。结果表明,卟啉类的Soret吸收带带宽及峰位置在三种状态下均不相同,L-B膜的情况介于溶液中的和固体下的情况之间,说明了在L-B膜中,卟啉分子存在着某种形式的聚集体,且在这种聚集体中分子间的相互作用程度比固体弱,可以认为L-B膜上的分子呈准晶体状态。     

Solubilization properties of N-substituted amphiphilic acrylamide copolymers

Amphiphilic copolymers of sodium 2-acrylamido-2-methylpropanesulfonate (AMPS) and dodecylmethacrylamide (DodMAAm) were synthesized. The ratio of the reduced viscosities of these copolymers in water and in 0.2 mol/L NaCl solution shows that these copolymers containing from 50 to 66 mol % of DodMAAm have a relatively small and constant hydrodynamic size. Viscometric and static light scattering measurements indicated that the copolymers shrinked and intermolecularly associated, forming interchain aggregates in water through hydrophobic interactions. These copolymers solubilize dl-α-tocopherol acetate, giving a transparent solution; but the solution became turbid in a month due to increasing intermolecular association. To suppress this excess intermolecular association, polymers with four different crosslinking ratios were synthesized. The polymer of a crosslinking ratio of 0.5 mol % showed a strong solubilization property, resulting in transparent solution with an improved stability. The fluorescence spectra of pyrene in the polymer solution proved that these copolymers could form strong hydrophobic domains, which solubilize a hydrophobic compound, in less than 30 w/w % ethanol solution. These copolymers could have an excellent function of sustained release of perfume as a novel function. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2447–2453, 1999     

Changes of fluorescence color in novel poly(azomethine) by the acidity variation

A novel polymer, poly(4,4′‐oxydiphenylenemethylidynenitrilo‐2,5‐dihexyloxy‐1,4‐phenylenenitrilomethyli‐ dyne) (POPNM), with a azomethine structure, containing long alkoxy side chains, was synthesized by the polycondensation of 2,5‐bis(hexyloxy)terephthalaldehyde with 4,4′‐oxydianiline. It displayed acid‐sensory properties as colorimetric and fluorescent transducers to the strong acid analytes because of the protonation of an imine group in the compound. To examine the sensitivity to the acid, the effect of absorption and fluorescence of the polymer was investigated by simply adding trifluoroacetic acid into a chloroform solution of the polymer, and as a result, the multiple colors of fluorescence were sharply changed. Increasing the amount of the acid, the maximum absorption bands of fluorescence spectra were bathochromically shifted from 470 to 570 nm and, then, treating the pyridine as a base, they were recovered. A polymer film containing both the polymer and a photoacid generator (PAG) was prepared by semi‐interpenetrating network polymerization method. When the polymer film was exposed to UV in the presence of PAG through a photomask, well‐resolved fluorescent image patterns were readily obtained. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1228–1233, 2006     

Fluorinated polymers as stone‐protective materials: an FTIR study on intermolecular interactions

Attempts have been performed to obtain spectroscopic evidence of intermolecular interactions between fluorinated polymers to be used as protective materials and various stones. In this paper we report an investigation by means of FTIR spectroscopy on poly(vinyl fluoride)(PVF) which contains acid hydrogens that can give rise to intermolecular interactions with calcium carbonate. Spectral changes have been found in the C? H and C? F stretching regions at 3000–2840 and 1200–950 cm^?1, respectively. These last are attributed to intermolecular interactions of the polymer with CO₃^2? and with conformational changes of the macromolecular chain. Scanning electron microscopy investigations were also performed on marble slabs coated with a PVF film in order to gain information about the morphology of the polymer film. Copyright © 2004 Society of Chemical Industry     

In situ ATR-FTIR studies of the aluminium/polymer interface upon exposure to water and electrolyte

Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) with the Kretschmann configuration was applied for in situ studies of the transport of water and ionic species through a polymer film to an aluminium/polymer interface. The time dependent intensity changes of the infrared bands of water were used to follow the transport of water to the aluminium/polymer interfacial region and a NaSCN solution was employed as model electrolyte to follow the transport and accumulation of thiocyanate ions. Apart from water sorption and ion transport, the main processes identified were corrosion/oxidation of the aluminium surface and swelling of the polymer film. The method proved to be useful for detailed in situ studies of changes at a polymer coated metal surface, such as oxidation and surface film formation on the metal. It should also be possible to study the effects of defects and pores in the polymer film on the transport properties of water and ions to the metal/polymer interface, as well as adsorption and other chemical reactions and physical interactions in the metal/polymer interfacial region.     

A novel emitting polymer with bipolar carrier transporting abilities

A luminescent bipolar polymer containing 1,3,4‐oxadiazole and triphenylamine has been synthesized. A smooth and dense thin film of polymer is easily obtained by spin coating its chloroform solution. This film exhibits a strong blue fluorescence under the irritation of ultraviolet (UV) light. The synthesized polymer possesses a high glass transition temperature (T_g) of 167°C. A single‐layer electroluminescence (EL) device indium‐tin oxide (ITO)/polymer/Mg:Ag emitted blue light with a turn‐on voltage of 13 V. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88:50–53, 2003     

含胆固醇基的两亲性羧甲基纤维素钠衍生物

首次合成出水溶性两亲性含胆固醇基的羧甲基纤维素钠衍生物(CCSD)。羧甲基纤维素钠(CMCNa)先被质子化成羧甲基纤维素(CMC),然后在偶联剂和催化剂的作用下CMC与胆固醇于室温进行反应,产物纯化后用碳酸钠中和至pH=7。用红外光谱法对CCSD产物进行了结构分析,1733cm-1的伸缩振动峰证实CMC中的羧酸与胆固醇的羟基发生了酯化反应。荧光光谱法研究了所合成的CCSD在0.15mol/L氯化钠水溶液中的胶束化行为,其临界聚集浓度为0.62 g/L。CCSD在亚浓溶液中呈现非牛顿流体中剪切稀化的特性,CCSD分子间存在疏水性胆固醇基之间的非极性―非极性相互作用力。     

Dependence of optical properties on the preparation methods of poly[(9,9′‐dialkylfluorene‐2,7‐diyl)‐alt‐(1,3,4‐oxadiazole‐2,5‐diyl)]

A blue‐light‐emissive fluorene‐based polyoxadiazole, an n‐type polyfluorene derivative, was synthesized by both one‐step and two‐step methods. Directly polymerized poly[(9,9′‐didodecylfluorene‐2,7‐diyl)‐alt‐(1,3,4‐oxadiazole‐2,5‐diyl)] (PFOx‐DP) exhibited a higher molecular weight and a more efficient photoluminescence quantum yield than poly[(9,9′‐didodecylfluorene‐2,7‐diyl)‐alt‐(1,3,4‐oxadiazole‐2,5‐diyl)] (PFOx) prepared via a polyhydrazide precursor, poly[9,9′‐didodecylfluorene‐2,7‐(2,5‐dihydrazide‐ 1,3,4‐oxadiazole). Both polymers, differently prepared, showed similar photoluminescent properties in 1,2‐dichloroethane. However, in a film state, the influence of the interchain interactions on the photoluminescence of PFOx with the lower molecular weight was larger than on the photoluminescence of PFOx‐DP. The electron‐deficient property of an oxadiazole group in the polymer backbone resulted in low‐lying highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels of ?6.29 and ?3.26eV, respectively, of the polymer suitable for electron‐transport/hole‐blocking layers and emissive layers in multilayer electroluminescence devices. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3112–3118, 2004     

Synthesis of a novel fluorene-based conjugated polymer with pendent bulky caged adamantane moieties and its application in the detection of trace DNT explosives

A novel fluorene-based conjugated polymer with phenylene spacers and steric bulky adamantane moieties in side chains has been synthesized by palladium-catalyzed Suzuki coupling reactions. This design strategy offers several advantages for the detection of trace 2,4-dinitrotoluene (DNT) vapor. The incorporation of the two groups into polymer side chains could retain an effective conjugation length and prevent the π-stacking of polymer chains. The detection of DNT vapor indicated that the polymer displayed higher fluorescence quenching sensitivity toward the explosives in films compared to reference polymers. The fluorescence quenching efficiency of the fluorescent polymer achieved 33.3% in 10 s and 71.1% in 60 s. The pathways or cavities generated by the two spacers are beneficial for the rapid diffusion of explosive vapor into the film interiors and increase the fluorescence quenching efficiency of the film.     

Synthesis and properties of various PPV derivatives with phenyl substituents

New electroluminescent polymers with various phenyl groups, poly[2-dimethyl(octyl)silyl-5-(4-(dimethyl(octyl)silyl)phenyl)-1,4-phenylenevinylene] (P1), poly[2,5-bis(4-(dimethyl(octyl)silyl)phenyl)-1,4-phenylenevinylene] (P2), poly[2,5-bis(9,9-dihexylfluorenyl)-1,4-phenylenevinylene] (P3), and poly[2,5-bis(4-(4-(2-etylhexyloxy)phenyl)phenyl)-1,4-phenylenevinylene] (P4), have been synthesized by the Gilch polymerization. The maximum absorption peaks of P1-P4 appeared at 388-423 nm in THF solution, and are red-shifted to 404-425 nm in solid thin film. The photoluminescence (PL) emission spectra of P1-P4 show a maximum peak at 482-503 nm in THF solution and at 521-549 nm as the solid film state. The emission spectra in the solid film state are more red-shifted over 40 nm, and the full width at half maximum (fwhm) was 30 nm greater than the solution conditions. The polymer light-emitting diodes (PLEDs) with the configuration of ITO/PEDOT/polymer/Al emitted light with maximum peaks at around 517-546 nm. The various phenyl substituents, with intermolecular interactions in the solid film state, can introduce the color tuning and device performance enhancement of the conjugated polymer as an emissive layer in PLED.     

Interactions Between Gold Nanoparticles and Polymer Bearing 3-Styryl Thiophene Chromophores

The interactions between gold nanoparticles and a novel acrylate copolymer bearing 3-styryl thiophene chromophores were studied spectrally and electrochemically. The emission intensity of the polymer solution can be quenched by gold nanoparticles. Collisional quenching is likely the main mechanism for the deactivation process and heterogeneous electron transfer takes place in the process. For the solid polymer film, the presence of gold nanoparticles reduces the emission intensity of the single chromophore as well as the intensity of the excimers. Cyclic voltammetry (CV) investigations indicate that the polymer solution exhibits no oxidation wave. However, in the presence of gold nanoparticles, either by directly addition to the polymer solution or by deposition on the ITO electrode, the polymer solutions possess distinct CV oxidation peak(s), indicating that the gold nanoparticles may mediate the contact and enhance the electron transfer between the electrode and chromophores.     

Butyl pyrene containing poly(arylene ethynylene)s for highly sensitive and selective sensing of TNT

A series of poly(arylene ethynylene)s (PAEs) containing ^tbutyl pyrene in the main chain were synthesized for nitroaromatic sensors. As control, similar polymers containing unsubstituted pyrene were also synthesized. The sensory properties of the polymers were studied towards various nitroaromatic compounds like trinitrotoluene (TNT), dinitrotoluene (DNT), nitrotoluene (NT), nitrobenzene (NB) and picric acid (PA) in solution as well as vapor state. Interestingly, all the ^tbutyl substituted pyrene containing polymers showed higher sensitivity than the corresponding unsubstituted pyrene containing polymers. Moreover, the polymers showed high sensitivity towards TNT as compared to the other nitroaromatic compounds. The sensitivity of one of the polymer PB was found several folds higher than that of the similar reported polymer containing unsubstituted pyrene ring. In addition, ^tbutyl pyrene containing polymers were found to have improved molecular weight, thermal stability, fluorescence quantum yield, film forming properties and solubility in common organic solvents as compared to the control polymers.     

Preparation and photophysical properties of organic fluorescent polymers and their nanoparticles

New classes of stable organic florescent polymer nanoparticles were prepared from the corresponding tetrahydrofuran (THF) solutions, upon slow evaporation of solvent under a mild vacuum. Uniform spherical nanospheres having mean diameter of ? 500–700 nm, showed enhanced fluorescence emission in solution, but it diminished when it is destroyed using an organic base. These end‐capped fluorescent polymers are highly stabilized in the excited states at higher concentration in solution, leads no more intra‐ and intermolecular interactions among the excited molecules, because of the absence of free functional groups. The significant enhancement in fluorescence emission was attributed to the high level of molecular stacking in the fluorescent nanoparticles, when compared with micron‐sized isolated powder sample. In addition, these fluorescent polymers exhibited significant thermal properties, along with better solubility in most of common organic solvents for their future application. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5344–5350, 2006     

Effects of reaction variables on the reproducibility of the syntheses of poly-1,3,4-oxadiazole

Important engineering aspects related to the production of polyoxadiazole (POD), from the polycondensation of 4′4′-diphenyl-ether-dicarboxylic acid (DPE), and hydrazine sulphate (HS), in poly(phosphoric acid) (PPA), such as reproducibility of final polymer properties and sensitivity to initial feed charge, were investigated. When the reaction variables are not tightly controlled, large variations of molecular weight and macromolecular structure of polymer materials synthesized at similar reaction conditions may be observed. These experimental fluctuations pose a challenge for the design and scale-up of POD synthesis. It seems that the two most fundamental sources of experimental perturbation are the degradation of the polymer chains during the purification step and the composition fluctuations during feeding of the reaction system. Despite of that, polymer samples without residual hydrazide group and with high molecular weights (higher than 200 kDa) can always be obtained when the final polymer sample is shredded and homogenized, the pH of the suspension that contains the precipitated polymer is rigorously controlled and the local fluctuations of the initial feed composition are minimized through the increase of the reaction scale. This indicates that the final purification of the POD is of fundamental importance for proper control of the final polymer properties.     

A new positive-type photoreactive polyimide precursor using 1,4-dihydropyridine derivative

A novel positive-type polyimide precursor (BPDA/DDE) has been developed and examined. It is synthesized by the polycondensation of biphenyltetracarboxylic acid dianhydride and 4,4′-diamino-diphenyl ether, based on systems composed of dimethyl 1,4-dihydro-2,6-dimethyl-4-(2-nitrophenyl)-3,5-pyridinecarboxylate (nifedipine). Nifedipine photoconverted quantitatively to 4-(2′-nitrosophenyl)-2,3-dicarboxymethyl-3,5-dimethylpyridine (NDMPy) in a polyimide precursor film. It has been confirmed that nifedipine and NDMPy in the film act as a dissolution inhibitor and as a disolution promotor, respectively. The dissolution inhibition and promotion mechanisms were further investigated and subsequently expressed as follows:

• (1) Dissolution inhibition is due to resistivity of the polyimide precursor to an alkaline aqueous solution through intermolecular hydrogen bonding between — COOH in the polymer structure and — NH — in nifedipine.
• (2) Dissolution promotion is due to the hydrogen bond-breaking by photoconversion from nifedipine to NDMPy and the newly formed intermolecular complex between the COOH and ? N? in NDMPy.

The photoreactive polyimide precursor (BPDA/DDE), including 25wt% nifedipine, shows a 170mJ/cm² sensitivity and a 5.5 γ value.     

A study on the solution behavior of IPBC‐hydrophobically‐modified hydroxyethyl cellulose

Through the macromolecule reaction method, a series of 4‐isopropylbenzyl chloride (IPBC) hydrophobically‐modified hydroxyethyl cellulose (HAHEC) were synthesized. The use of suitable amount of hydrophobic monomer can ensure both the strong intermolecular association and good water‐solubility of HAHEC. Effects of polymer concentration, shear rates, temperature, and electrolytes on the solution behavior of HAHEC were comprehensively studied, which indicated that the polymers show high viscosification property, excellent viscosity retention in brine water, and surface activity. FTIR, DSC, and UV measurements were applied to characterize the molecular structure and composition of HAHEC to confirm the incorporation of hydrophobic group into the polymer chain. Atomic force microscope (AFM) and fluorescence spectrum measurements were applied to study the formation of the molecule aggregation and hydrophobic microdomain of HAHEC, and revealed the close relationship between the rheological behaviors and the hydrophobic viscosification effect. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2824–2831, 2006     

Study on the rheological behavior of the hydrophobically modified hydroxyethyl cellulose with 1,2‐epoxyhexadecane*

Through the macromolecule reaction method, the hydrophobically modified hydroxyethyl cellulose (EP16–HAHEC) was synthesized using 1, 2‐epoxyhexadecane as the hydrophobic monomer. The solution properties of EP16–HAHEC were comprehensively investigated, which showed that the polymer with enhanced; viscosification property, thermal stability, shear resistance, and salt resistance was obtained. Amphiphilic structure of EP16–HAHEC molecules contributed to the surface activity of the polymer. By forming complex solution with surfactants or carboxylmethyl cellulose (CMC), the viscosification property of EP16–HAHEC could be enhanced through the interactions of hydrophobic groups and hydrogen bonds. The viscosity‐enhancing mechanism of HAHEC was studied by the environment scan electronic microscope (ESEM) and the fluorescence spectrum measurements, which demonstrated that the formation of the supramolecular aggregation networks was coincident with the increase of the apparent viscosity of HAHEC. With the gradual formation of the complete polymer molecule networks, the apparent viscosity rised dramatically, and the associating aggregations of the polymer molecules appeared far before the great change of the macroproperty of the polymer. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2953–2959, 2006     

Synthesis,characterization and fluorescence quenching of conjugated polymer containing triphenylamine group

Poly(triphenylamine-p-phenylenevinylene)s with two different end-groups were obtained through a Wittig polycondensation. The structures of two copolymers were characterized. Ultraviolet and visible spectroscopy (UV-Vis) and photoluminescence (PL) spectra show the end-capped polymer emits intensive green light in both solution and film state. Their applications in the detection of nitro compounds were investigated, and the results show high fluorescence quenching sensitivity of the end-capped polymer towards o-nitrotoluene (o-NT). When the concentration of o-NT was 21.5 × 10^-3 mol/L, the fluorescence quenching reached 96%. Additionally, after the exposure of polymer film in three different quenchers such as dinitrotoluene (DNT), p-nitrobenzoquinone (p-BQ) and p-nitrotoluene (p-NT) for 600 s, its fluorescence quenching reached 93.6%, 11.5% and 77.9%, respectively. This kind of polymer has great advantages in preparation and may find applications in the detection of nitro explosives.     

疏水缔合聚合物的合成及溶液性质研究

Acrylamide/2-acrylamido alkane sulfonic acid hydrophobic associating copolymers were synthesized by micellar copolymerization. Effects of hydrophobe content, polymer concentration, salinity and surfactant on rheological behavior of copolymers were investigated and the conformation of polymers in solution was studied by means of environmental scanning electronic microscopy and dynamic light scattering. The experimental results showed that in the dilute regime the hydrophobic parts could interact intramolecularly, while in the regime where the polymer concentration was higher than the critical association concentration, intermolecular hydrophobic association became predominant. Within the limit of the solubility, the critical association concentration of the polymer decreased with the increase of the salinity. The experimental results of the solution conformation indicated the presence of the three-dimensional network structure in deionized water and the size of the mesh in the network varied with the polymer concentration. In NaG1 solution, above the critical association concentration, an increase in polymer concentration enhanced the intermolecular association and also enlarged the hydrodynamic radius. It would result in the imorovement of the thickening power of polvmers.