Studies on the thermotropic liquid crystalline polymer. I. Synthesis and properties of polyamide-azomethine-ether

A series of polyamide-azomethine-ethers was prepared by condensation of 4,4′-diaminoanilide with 4,4′-diformyl-α,ω-diphenoxyalkane, 4,4′-diformyl-3,3′-methoxy-α,ω-diphenoxyalkane, and 4,4′-diformyl-3,3′-ethoxy-α,ω-diphenoxyalkane, respectively. The inherent viscosities of polymers were obviously increased when the polymers were treated by heat under nitrogen at 220°C. The thermotropic liquid crystalline properties were examined by DSC, microscope observations, and TGA. All of the polymers, except polymer A-1, exhibit thermotropic liquid crystalline properties. They also exhibit threaded and/or Schlieren textures examined by the polarizing microscope which indicate a nematic phase. In most cases, the mesophase exists up to ca. 400-460°C shown by TGA study. The mesophase cannot exist above 400-460°C because of the thermal decomposition.     

含氧膦结构的可溶性感光聚酰亚胺合成与表征

聚酰亚胺(PI)是一类综合性能优异的功能性材料,广泛应用于航天、航空及电子工业等领域[1].感光聚酰亚胺可以采用光刻工艺,大大简化了其应用加工程序[2,3],因而备受人们所青睐.含查尔酮结构的聚合物对UV辐射敏感度高和化学稳定性好,最近被广泛的研究和应用[4～7].主链含查尔酮结     

Kinetic and mechanistic studies of the I(2)/O(3) photochemistry

The atmospherically relevant chemistry generated by photolysis of I2/O3 mixtures has been studied at 298 K in the pressure range from 10 to 400 hPa by using a laboratory flash photolysis setup combining atomic resonance and molecular absorption spectroscopy. The temporal behaviors of I, I(2), IO, and OIO have been retrieved. Conventional kinetic methods and numerical modeling have been applied to investigate the IO self-reaction and the secondary chemistry. A pressure independent value of k(IO + IO) = (7.6 +/- 1.1) x 10(-11) cm(3) molecule-1 s(-1) has been determined. The pressure dependence of the branching ratios for the I + OIO and IOIO product channels in the IO + IO reaction have been determined and have values of 0.45 +/- 0.10 and 0.44 +/- 0.13 at 400 hPa, respectively. The branching ratios for the 2I + O(2) and I(2) + O(2) product channels are pressure independent with values of 0.09 +/- 0.06 and 0.05 +/- 0.03, respectively. The sensitivity analysis indicates that the isomer IOIO is more thermally stable than predicted by theoretical calculations. A reaction scheme comprising OIO polymerization steps has been shown to be consistent with the temporal behaviors recorded in this study. For simplicity, the rate coefficient has been assumed to be the same for each reaction (OIO)(n) + IO --> (OIO)(n+1), n = 1, 2, 3, 4. The lower limit obtained for this rate coefficient is (1.2 +/- 0.3) x 10(-10) cm(3) molecule(-1) s(-1) at 400 hPa. Evidence for the participation of IO in the polymerization mechanism also has been found. The rate coefficient for IO attachment to OIO and to small polymers has been determined to be larger than (5 +/- 2) x 10(-11) cm(3) molecule(-1) s(-1) at 400 hPa. These results provide supporting evidence for atmospheric particle formation induced by polymerization of iodine oxides.     

CARBAZOLE-CONTAINING HYPERBRANCHED POLY（ARYLENEETHYNYLENE）S： SYNTHESIS, CHARACTERIZATION, AND PROPERTIES

New hyperbranched poly(aryleneethynylene)s containing carbazole moieties are synthesized in high yields(up to 87%)by polycyclotrimerization of 3,6-bis(4-ethynylphenyl)-9-octylcarbazole and its copolymerization with 1-octyne catalyzed by CpCo(CO)_2 in THF.The structures and properties of the polymers are characterized and evaluated by IR,NMR, TGA,UV,photoluminescence,and cyclic voltammetry analyses.All the polymers are soluble in common organic solvents and show outstanding thermal stability(≥430℃).They graphitize in high yields(up to 79%)when pyrolyzed at 800℃. Upon photoexcitation,the polymers emit a strong deep blue light of ca.400 nm with quantum yields larger than 60%.     

Synthesis and characterization of new ointment-like poly(ortho esters)

Ointment-like poly(ortho esters) were synthesized for the first time from the reaction of 3,9-bis(methylene)-2,4,8,10-tetraoxaspiro[5. 5] undecane with poly(ethylene glycol)-400, N,N-bis(2-hydroxyethyl)-n-hexadecylamine and N,N-bis(2-hydroxyethyl) palmitamide, respectively. The obtained polymers were characterized by 1H NMR spectra, 13C NMR spectra, elemental analyses, light scattering, and measurements of intrinsic viscosity. The influence of catalyst on the intrinsic viscosity of polymers was investigated. The 9-[(1,3-dihydroxy-2-propoxy) methyl] guanine controlled release profiles of hydrophobic ointment-like polymers such as polymer P_II in vitro were also discussed.     

SN-conducting polymers with heterocyclic spacer groups

Polymer-containing alternating sulfur nitrogen moieties separated by heterocyclic groups have been synthesized and characterized. The polymers have undoped conductivities of 10^?6 to 10^?9 (Ω cm)^?1; the intrinsic carriers are negatively charged as shown by thermopower coefficient of ?1.4 × 10³ to ?1.9 × 10³ μV K^?1. The polymers are degraded by AsF₅ and cannot be doped by iodine. Exposure to bromine resulted in reversible p-doping of the SN polymers to the thermopower values of +400 to +820 μV K^?1 and conductivities of 0.01 to 0.002 (Ω cm)^?1. Removal of dopant by evacuation returns most of the properties of the polymers to the undoped states. Magnetic properties of the materials have been studied.     

Molecularly imprinted solid-phase extraction of matrine from radix Sophorae tonkinensis

In the study, molecularly imprinted polymers (MIPs) with special molecular recognition properties of matrine (MAT) were prepared in our lab, using melamine-urea-formaldehyde (MUF) as the functional monomer and matrine as the template. An equilibrium binding experiment was performed to investigate the binding ability of the MIPs, and indicated that the MIPs had a high adsorption and good elution ability to the target molecule MAT, when the template/functional monomer ratio (T/M) was 5 mg g(-1). Scatchard analysis and isothermal equilibrium adsorption indicated that only one kind of binding site had existed in the MAT-imprinted polymers with its dissociation constants estimated to be 3.31 × 10(-4) mol L(-1) (200-400 mesh (inch(-1))) and 6.83 × 10(-4) mol L(-1) (over 400 mesh (inch(-1))) depending on the mesh of the MIPs. MAT purification and elution experiments were carried out using MIPs as the solid-phase extraction (MISPE) sorbent, and acetone, water, and chloroform as the elution solvents. The results demonstrated that MIPs achieved their highest adsorption capability after treatment with alkaline solution, while acetone was the most efficient elution solvent. Then, a crude extraction of matrine in radix Sophorae tonkinensis was performed using these MIPs as the separation medium. The results showed that MIPs had a high MAT selectivity, and the amount of matrine content obtained by MISPE was 1.4-fold to that obtained by liquid-liquid extraction.     

Surface imprinted thin polymer film systems with selective recognition for bovine serum albumin

Molecularly imprinted polymers are synthetic antibody mimics formed by the crosslinking of organic or inorganic polymers in the presence of an analyte which yields recognitive polymer networks with specific binding pockets for that biomolecule. Surface imprinted polymers were synthesized via a novel technique for the specific recognition of bovine serum albumin (BSA). Thin films of recognitive networks based on 2-(dimethylamino)ethyl methacrylate (DMAEMA) as the functional monomer and varying amounts of either N,N′-methylenebisacrylamide (MBA) or poly(ethylene glycol) (400) dimethacrylate (PEG400DMA) as the crosslinking agent were synthesized via UV free-radical polymerization and characterized. A clear and reproducible increase in recognition of the template BSA was demonstrated for these systems at 1.6-2.5 times more BSA recognized by the MIP sample relative to the control polymers. Additionally, these polymers exhibited selective recognition of the template relative to competing proteins with up to 2.9 times more BSA adsorbed than either glucose oxidase or bovine hemoglobin. These synthetic antibody mimics hold significant promise as the next generation of robust recognition elements in a wide range of bioassay and biosensor applications.     

聚合物内压测定及对应状态模型

实验测定了PEG(M~n=200),PEG(M~n=300),PEG(M~n=400),PDMS(M~w=15000)和PDMS(M~w=20000)在20-90℃温度范围的热压力系数和密度,它们的热压力系数和内压几乎与分子量无关。据此还建立了一个聚合物内压的对应状态模型,它只含一个可调参数,能满意地适用于各种聚合物。     

Synthesis and light-emitting properties of disubstituted polyacetylenes carrying chromophoric naphthylethynylphenyl pendants

Poly(1-phenyl-1-alkyne)s bearing chromophoric pendants and containing alkyl spacers (-{(C 6H 5)CC[(CH 2) m OCOC 6H 4CCNp]} n - [P 1( m) ( m = 3, 4, 9); Np = 1-naphthyl]) were synthesized, and the effects of structural variations on the optical properties, especially electroluminescence, of the polymers were investigated. The monomers were prepared in high yields by esterification and coupling reactions of n-phenyl-( n - 1)-alkyn-1-ols. Selective polymerizations of the 1-phenyl-1-alkyne unit of the monomers were effected by WCl 6-Ph 4Sn catalyst, affording polymers with high molecular weights ( M w up to 63 000) in high yields (up to 83%). Structures and properties of the polymers were characterized and evaluated by IR, NMR, TGA, UV, PL, and EL analyses. All the polymers are thermally very stable, losing almost no weight when heated up to 400 degrees C. Photoexcitation of the polymer solutions induces strong blue light emission at 460 nm, with quantum yields up to 98%. No aggregation quenching was observed when the polymers were fabricated into solid films. Multilayer EL devices with the configuration of ITO/P 1( m):PVK/BCP/Alq 3/LiF/Al were fabricated, which emitted blue light with luminance up to 498 cd/m (2). The device performance varied with the spacer length ( m), with P 1(4) giving the highest external quantum efficiency of 0.47%. The value was further enhanced to 0.86% by optimizing the layer thickness and inserting a hole-injection layer.     

Compared properties of related aromatic poly(1,3,4-oxadiazole-amide)s

Two series of aromatic poly(1,3,4-oxadiazole-amide)s have been synthesized by low-temperature solution polycondensation reaction of equimolar amounts of aromatic diamines containing preformed oxadiazole rings with diacid chlorides having silicon or hexafluoroisopropylidene groups. These polymers are soluble in polar aprotic solvents and show high thermal stability with decomposition temperature being above 400 °C and glass transition temperature in the range of 250-350 °C. The polyoxadiazole-amides have weight- and number-average molecular weights in the range of 207 000-330 000 and 77 000-131 000, respectively. Conformational parameters of these polymers were calculated by Monte Carlo method with allowance for hindered rotation and discussed in relation with thermal properties. Polymer solutions in NMP were processed into thin free-standing films that showed good mechanical properties with tensile strength in the range of 50-100 MPa, tensile modulus in the range of 2.25-3.56 GPa and elongation to break in the range of 1.65-8.58%.     

Aromatic polymers with side oxadiazole rings as luminescent materials in LEDs

Aromatic polyamides and polyazomethines with side oxadiazole rings have been synthesized by using aromatic diamines containing pendent substituted oxadiazole groups and a diacid chloride having diphenylsilane or hexafluoroisopropylidene, or an aromatic dialdehyde with fluorene unit, respectively. These polymers were easily soluble in amidic solvents. Very thin films which were deposited from polymer solutions onto silicon wafers exhibited smooth, pinhole-free surface in atomic force microscopy investigations. The polymers showed high thermal stability with decomposition temperature being above 400°C. Some of them exhibited blue photoluminescence, in the range of 450-480 nm, making them promising candidates for future use as high performance materials in the construction of light emitting devices.     

Green synthesis of polymers containing phosphorus in the main chain

New structures of polymers containing phosphorus in the main chain were prepared by interfacial polycondensation of phenylphosphonic dichloride with 4,4’-(1,3-phenylenediisopropylidene) bisphenol (bisphenol M) using two different methods: method I: gas–liquid interfacial polycondensation without an organic solvent and a catalyst; and method II: solid–liquid interfacial polycondensation using green solvents and without catalyst. The aim of this work was to apply these methodologies as eco-friendly and economical procedures for a green chemistry. The polymers were characterized by gel permeation chromatography (GPC), FT-IR, ¹H and ³¹P-NMR spectroscopy, differential scanning calorimetry (DSC) and thermal analysis. Yields in the range of 88.0–90.0, and inherent viscosities in the range of 2.2–3.2 dl/g were obtained. High molecular weight polymers (57 600–114 400) have been successfully prepared. The polymers are self-extinguishing and begin to lose weight at around 300 °C. The flammability was investigated by measuring limiting oxygen index values (LOI).     

Adamantyl-substituted phenolic polymers

4-(1-Adamantyl)phenol was synthesized via Friedel-Crafts reaction of 1-bromoadamantane and phenol. Substitution in the phenol para position forces polymerization to occur only in the ortho positions to give a linear polymer. Variations in formaldehyde amount, reaction time, and catalyst were evaluated. Increasing the amount of paraformaldehyde increased formation of cyclic octamer, an easily identified by-product due to its insolubility in common organic solvents. The cyclic octamer was acetylated to give a soluble model compound for comparison to acetylated polymers by IR and NMR. All of the synthetic variations employed produced low molecular weight polymers as indicated by NMR end-group analysis and SEC. The polymers showed number-average molecular weights of ca. 3000 (versus polystyrene standards by SEC), and exhibited glass transition temperatures ranging from 175–230°C, an increase of ca. 100°C over unsubstituted and para-alkyl substituted analogs. All of the samples exhibited a 10% weight loss at 400°C in nitrogen, indicating thermal stability much greater than the parent and alkyl-substituted polymers. © 1996 John Wiley & Sons, Inc.     

Polycycloalkylene-siloxane polymers: Synthesis and thermal study

Based on dicyclopentadiene and silacyclopentene, two linear polycycloalkylene-siloxane polymer systems have been synthesized and the thermal stability of the raw polymers evaluated by differential scanning calorimetry and thermal gravimetric analysis. The DSC data in nitrogen indicate that both polymer systems have excellent thermal stability. In air, these polymers begin to oxidize at approximately 150°C, with catastrophic oxidation occurring at about 400°C.     

Temperature induced single-crystal-to-single-crystal transformations and structure directed effects on magnetic properties

The binding of CoII, NiII, and CuII cations to the lithium 3-pyridinesulfonate ligand in an aqueous solution leads to single crystals of coordination polymers 1-3. The solid-state architectures of 1-3 which resulted from the combination of ligand-water heterocomplexation processes are linear coordination polymers packed into parallel alternatively stratified layers. These layers are interconnected through intermolecular hydrogen-bonding interactions occurring between the coordinated water molecules and the noncoordinating oxygen atoms of the sulfonate groups. Consequently, this leads to the formation of the cross-linked 3D (1, 2) or layered 2D (3) networks exhibiting 12-point or four-point hydrogen bond contacts between each unit with eight or four adjacent neighbors, respectively. The reversible structural rearrangement of these frameworks proceeds from the "relaxed" room-temperature phase to the "contracted" low-temperature phase in response to an external thermal stimulus. The reversibility of the contraction/relaxation process has been tested and confirmed by X-ray analysis. Motions toward shortening intermolecular distances have the consequence of increasing the degree of magnetic interaction between the metal ions. The magnetic measurements carried out in the range 1.8-400 K on the three compounds show an unusual change from antiferromagnetic to ferromagnetic behavior related to the structural variations recorded at low temperatures and to the loss of water above 350 K.     

Studies on phthalocyanine sheet polymers

Cobalt, nickel and copper phthalocyanine sheet polymers are synthesized by heating their respective metal (II) phthalocyanine tetracarboxylic acids at 400 °C in nitrogen atmosphere. These polymers are characterized using UV-Visible spectra, IR spectra, magnetic susceptibility, X-ray powder diffraction and thermogravimetric analysis. Electrical conductivity studies are carried out using two-probe technique in the temperature range 25-200 °C for each polymer. These polymeric materials showed room temperature electrical conductivity 10-1000 times higher values compared to earlier reported values for this type of sheet polymers.     

Synthesis and properties of poly(arylene ether phenyl-s-triazine)s

A series of new poly(arylene ether phenyl-s-triazine)s was prepared by the nucleophilic aromatic substitution polymerization of the potassium salt of bisphenols with 2,4-bis (halophenyl)-6-phenyl-s-triazine in N-methyl-2-pyrrolidone at elevated temperature. The polymers with inherent viscosities exceeding 0.5 were obtained after polymerization for 1 h using 2,4-bis(fluorophenyl)-6-phenyl-s-triazine as a monomer. The glass transition temperatures of the resulting polymers ranged from 200 to 260°C depending on the bisphenol used in the polymer synthesis. The poly(arylene ether phenyl-s-triazine)s demonstrated excellent thermal stabilities in excess of 490°C (5% weight loss in air). The isothermal TGA measurements (400°C under air or nitrogen atmosphere) revealed that the 4,4'-biphenol- and hydroquinone-based poly(arylene ether phenyl-s-triazine)s belong to the most superior class of heat resistant polymers, such as polyimide Kapton?. The mechanical properties of these polymers are also described. © 1994 John Wiley & Sons, Inc.     

Synthesis of Polymers by Using Fluorene. VI. Free-Radical and Anionic Polymerizations of 9-Fluorenyl and 9-Phenyl-9-fluorenyl Methacrylates

9-Fluorenyl (FMA) and 9-phenyl-9-fluorenyl methacrylates (PFMA) were prepared from methacryloyl chloride with 9-fluorenol and from silver methacrylate with 9-phenyl-9-fluorenyl chloride, respectively. The polymerizations of FMA and PFMA were studied by using α,α′-azobisisobutyronitrile (AIBN), n-butyllithium (n-BuLi), and n-BuLi-(?)-sparteine (Sp) complex in toluene and tetrahydrofuran (THF). Only PFMA polymers obtained with the n-BuLi-Sp complex showed a specific rotation ([α]_D ²¹ ?3 to ?16° in THF).

The number-average molecular weights of the FMA and PFMA polymers were 7 700-16 900 and 1 400-4 700, respectively.     

Synthesis and characterization of novel poly（aryl ether）s containing naphthyl moieties

Two poly(aryl ether)s containing naphthyl moieties were prepared from bis(3,5-dimethyl-4-hydroxyphenyl)naphthyl methane (monomer 1) via nucleophilic aromatic substitution polycondensation with bis(4-fluorophenyl) ketone and bis(4-fluorophenyl) sulfone.The structures of these polymers were confirmed by ~1H NMR.The M_n values of the two polymers were 96,200 and 88,600, respectively.The polymers exhibited good thermal stabilities with 5%mass loss at T>400℃and high glass-transition temperature(T_g) of T>250℃...