耐高温新型含杂萘联苯聚醚砜嵌段共聚物的性能

将氯端基聚醚醚砜齐聚物和杂萘联苯类双酚羟端基齐聚物通过溶液缩聚,成功地合成了一系列新型聚醚醚砜-聚醚砜(PEES-PPES)嵌段共聚物,并用IR、DSC、TGA、X-WAXD等测试手段对聚合物进行了表征。结果表明:PEES-PPES具有较高的热稳定性,较好的溶剂溶解性;砜基比例的变化对PEES-PPES的热性能有较大的影响,表明砜基对杂萘联苯聚醚砜改性效果明显。     

Preparation and characterization of crosslinked polyimide–poly(dimethylsiloxane)s

Crosslinked polyimide–poly(dimethylsiloxane)s with theoretical content of the siloxane phase up to 60 wt% were prepared. The starting materials were p-aminophenyltrimethoxysilane terminated polyamic acids with number average molecular weight of 10,000 g mol⁻¹, based on 4,4′-oxydiphthalic anhydride and 4,4′-oxydianiline and dimethoxydimethylsilane. The structure of the prepared polymeric materials was analyzed using ²⁹Si and ¹³C NMR solid-state spectroscopy. Their thermal and mechanical properties, chemical resistance and density were evaluated. The influence of the basic catalysts employed (ammonium hydroxide) on the course of the reaction and properties of the materials was also studied.     

Polycondensation kinetics of poly(phenylene ether sulphone)

The synthesis of poly(phenyl ether sulphone) (from the potassium salts of 4,4′-dihydroxydiphenyl sulphone and 4,4′-dichlorodiphenyl sulphone or 4-chloro-4′-hydroxydiphenyl sulphone) was found to have different reaction kinetics according to the route used. By discriminating between rate constants (between monomer/monomer, monomer/polymer, polymer/polymer) a set of multi-parameter kinetic equations is obtained. Experimental and simulated values of the individual rate constants were in good agreement (for both the reaction rate and molecular weight distribution). The polycondensation reaction can be analysed, in terms of the component reactions.     

Radical copolymerization of sulphur dioxide and styrene: 4. Intramolecular excimer formation in poly(styrene sulphone)s

Intramolecular excimer formation in poly(styrene sulphone)s with various compositions has been investigated based on the characteristic monomer sequence distributions which were determined experimentally. The fluorescence spectra of the poly(styrene sulphone)s show two emission bands at 285 nm and 330 nm as for polystyrene, corresponding to the monomer and the excimer bands, respectively. The ratio of the excimer to the monomer emission intensities (I_e/I_m) is linearly correlated with the mole fraction of styrene. This observation is a consequence of the characteristic sequence distributions in poly(styrene sulphone)s. containing a very small fraction of SMS units (S = SO₂; M = styrene). The efficiency of excimer formation in poly(styrene sulphone)s with regular styrene sequences, e.g. dyad sequence only, was calculated from the sequence distribution and empirical I_e/I_m. It is concluded that the excimer formation in poly(styrene sulphone)s is very efficient. Energy migration along the copolymer chain was also demonstrated by measuring the degree of polarization as a function of copolymer composition. The efficient excimer formation and the depolarization in poly(styrene sulphone)s suggest that the SO₂ unit in poly(styrene sulphone)s does not act as a barrier or trap to energy migration unlike the methyl methacrylate unit.     

The effect of stress ageing on deformation in thin films of polystyrene and poly(ether sulphone)

Step-strain ridges are known to form when glassy polymers are subjected to a stepwise series of strain increments. For relatively short times between increments (ageing times) and at relatively low temperatures, these step-strain ridges (studied here in crazes in polystyrene and in deformation zones in poly(ether sulphone)) become more marked as the interval t_i between successive strain increments is increased. This is related to the phenomenon of stress ageing, as suggested by the approximate logarithmic dependence of the ridge height δ on t_i. However, at high temperatures, and or low molecular weight and relatively long t_i, δ may begin to decrease with t_i. This is argued to be a result of the onset of disentanglement in the aged material.     

Synthesis and characterization of poly(ether sulfone) and poly(ether sulfone ketone) copolymers

Poly(ether sulfone) and poly(ether sulfone ketone) copolymers (I–V) were synthesized by the nucleophilic substitution reaction of 4,4′-dihydroxy diphenyl sulfone (DHDPS, A) with various mole proportions 4,4′-difluoro benzophenone (DFBP, B) and 4,4′-difluoro diphenyl sulfone (DFDPS, C) using sulfolane as solvent in the presence of anhydrous K₂CO₃. The polymers were characterized by physicochemical and spectroscopic techniques. All polymers were found to be amorphous, and the glass transition temperature (T_g) was found to increase with the sulfonyl content of the polymers. ¹³C-nuclear magnetic resonance (NMR) spectral data was interpreted in terms of the compositional triads, BAB, BAC, CAC, ABA, and ABB, and indicate that transetherification occurs at high concentration of DFBP units in the polymer (IV). The good agreement between the observed and calculated feed ratios validates the triad analysis. Thermal decomposition studies reveal that the thermal stability of the polymers increases with increase in the carbonyl content in the polymer. Activation energies for thermal decomposition were found to be in the range of 160–203 kJ mol⁻¹ with the cleavage of ϕ SO₂ bond being the preponderant mode of decomposition and depended on the block length of the sulfonyl unit. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2113–2121, 1999     

The effect of tacticity on the conformational properties of poly(1-olefin sulfone)s

The effect of tacticity on the conformational properties of poly(olefin sulfone)s was studied. Tactic polymers, prepared from racemic thiirane monomers using chiral inititators were compared with atactic polymers prepared by free radical co-polymerisation of the 1-olefin with sulfur dioxide. Analysis of the XRD patterns showed that the tactic polymers formed more ordered structures in the bulk with longer layer spacings, consistent with a model in which their side chains meet at the tips in contrast with the atactic polymers whose side chains interdigitate. ¹³C MAS NMR experiments suggest that as tacticity increases so too does the proportion of C–S bonds in the gauche conformation, however the proportion of S–C bonds in the trans conformation falls, in contrast to a reported molecular mechanics study. Finally, DSC measurements on the polymers with longer side chains showed the presence of two endotherms on heating, illustrating definite liquid crystalline behaviour.     

Synthesis of poly(1‐hexene)s end‐functionalized with phenols

Electrophilic alkylations of phenol/2,6‐dimethylphenol were performed with vinylidene‐terminated poly(1‐hexene)s using BF₃·OEt₂ catalyst. Vinylidene‐terminated poly(1‐hexene)s with M_n varying from 400 to 10000 were prepared by bulk polymerization of 1‐hexene at 50 to ?20 °C using Cp₂ZrCl₂/MAO catalysts. The phenol/2,6‐dimethylphenol‐terminated poly(1‐hexene)s was characterized by NMR (¹H, ¹³C), UV, IR and vapor phase osmometer (VPO). The isomer distribution (ortho, para and ortho/para) was determined by ¹³P NMR using a phosphitylating reagent, namely 2‐chloro‐1,3,2‐dioxaphospholane. The number‐average degree of functionality (F_n) >0.9 with >95% para selectivity could be achieved using low‐molecular‐weight oligomers of poly(1‐hexene)s. Copyright © 2005 Society of Chemical Industry     

Silylated poly(4-hydroxystyrene)s as negative electron beam resists

Silylated poly(4-hydroxystyrene)s and radical polymerized 4-tert-butyldimethylsilyloxystyrene (TBDMSOSt) were examined as electron beam resists. Commercial poly(4-hydroxystyrene) (PHS) with M_w = 1.69 × 10⁴ and M_w/M_n = 5.41 was silylated with 1-(trimethylsilyl)imidazole and tert-butylchlorodimethylsilane. Both silylation reactions proceeded quantitatively to afford trimethylsilylated PHS with M_w = 3.93 × 10⁴ and M_w/M_n = 4.91, and tert-butyldimethylsilylated PHS with M_w = 4.08 × 10⁴ and M_w/M_n = 3.81. These 2 silyl ether polymers acted as a negative working resist to electron beam (EB) exposure. Sensitivity and contrast of tert- butyldimethylsilylated PHS were not affected by prebake temperature around its T_g of 97°C, while those of PHS were dependent on prebake temperature around its T_g of 160°C. At a prebake temperature of 125°C, the sensitivity parameter and the contrast γ value were obtained as follows: 3.93 × 10⁻⁴ C cm⁻² and 0.91 for PHS; 1.49 × 10⁻⁴ C cm⁻² and 1.06 for trimethylsilylated PHS; 1.84 × 10⁻⁴ C cm⁻² and 1.44 for tert-butyldimethylsilylated PHS. The silylation procedures obviously improved the sensitivity of PHS. TBDMSOSt was polymerized in bulk at 60°C with 2,2′-azobisisobutyronitrile (AIBN) as an initiator. The resultant poly(TBDMSOSt) possessed M_w = 3.01 × 10⁵ and M_w/M_n = 1.92 and exhibited a sensitivity of 1.60 × 10⁻⁵ C cm⁻² and a γ value of 1.47. More than 10 times enhancement of sensitivity was observed compared with tert-butyldimethylsilylated PHS. Such a high sensitivity is probably due to the high molecular weight of the bulk polymerized material. Poly(TBDMSOSt) resolved an isolated line of 0.20 μm width and 0.5 μm line and space patterns. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 1151–1157, 1998     

Solid state NMR study of the polymerisation of poly(ether sulphone)

The synthesis of poly(ether sulphone) using the ‘carbonate’ route based on the reaction of 4,4′-dihydroxydiphenylsulphone, 4,4-dichlorodiphenylsulphone and potassium carbonate dispersed in diphenylsulphone has been studied by ¹³C CPMAS NMR spectroscopy. In the initial reaction the half potassium salt of 4,4′-dihydroxydiphenylsulphone is formed. No evidence for a stable full salt was found at any time during the polymerisation cycle and no appreciable oligomer formation took place before the polymerisation itself took place.     

Hydrolysis of lactic acid based poly(ester-urethane)s

The hydrolysis behaviour of lactic acid based poly(ester-urethane)s has been studied in a buffer solution of pH 7·00 at 37 and 55°C. Samples were prepared using a straight two step lactic acid polymerization process. The lactic acid was first polymerized by condensation with a low molecular weight by hydroxyl terminated telechelic prepolymer and the molecular weight then was increased with a chain extender such as a diisocyanate. In the hydrolysis study, the effect on the hydrolysis rate of different stereostructures (different amount of D -units in the polymer chain) and the length of the ester units were studied. The rate of hydrolysis was examined by various techniques including weighing (water absorption and weight loss), GPC (molecular weight and polydispersity), and DSC (thermal properties). GPC measurements showed that at 37°C the weight average molecular weight of the poly(ester-urethane)s started to decrease slowly during the first week of hydrolysis, but that at 55°C the weight average molecular weight decreased dramatically during the first week of hydrolysis. Significant mass loss occurred later at both temperatures. © 1998 Society of Chemical Industry     

Solid state polymerization of bis(trichlorophenoxo) cobalt(ii) complex to give poly(dichlorophenylene oxide)

Synthesis of four-coordinated (tetrahedral) trichlorophenol cobalt(II) complex with neutral ligand pyridine was achieved from the aqueous solution and its characterization was performed by UV-visible, IR spectral and CHN analysis. Solid state thermal polymerization of the complex was accomplished first at constant temperature employing different time intervals and secondly at constant decomposition time. The poly(dichlorophenylene oxide)s so synthesized were characterized by IR, ¹H NMR and ¹³C NMR spectral analysis, T_g determination, as well as measurement of molecular weight by a viscometric method.     

The Mannich bases in polymer synthesis: 3. Reduction of poly(β-aminoketone)s to poly(γ-aminoalcohol)s and their N-alkylation to poly(γ-hydroxy quaternary ammonium salt)s

Several poly(β-aminoketone)s, obtained by polyconensation of bis Mannich bases with bis (secondaryamine)s, have been quantitatively reduced to poly(γ-aminoalcohol)s. The stereochemistry of these polymers, as well as that of the reduction products of the parent bis Mannich bases has been investigated. By N-alkylation of the same polymers, poly(γ-hydroxy quaternary ammonium salt)s have been also prepared.     

Diacid architecture effect on the synthesis and microstructure of rigid‐rod poly(benzobisthiazole)s

Six poly(benzobisthiazole)s (PBTs) have been synthesized by the solution polycondensation of 2,5‐diamino‐1,4‐benzenedithiol in poly(phosphoric acid) (PPA) with systematically varied diacids to demonstrate the diacid architecture effect of the aromatic heterocyclic rigid‐rod polymers. The role of PPA is identified and the effects of phosphorus pentoxide and water on PBT during polycondensation are discussed. Polymer properties such as the inherent viscosity and decomposition temperature are correlated to the diacid chemistry. The effect of diacid architecture on the synthesis and microstructure of PBT is studied. The results are discussed in terms of resonance, symmetry, and solubilization of the diacids. Copyright © 2006 Society of Chemical Industry     

New fluorinated poly(1,3,4-oxadiazole-ether-imide)s

New fluorinated poly(1,3,4-oxadiazole-ether-imide)s have been prepared by solution polycondensation reaction of different aromatic diamines having preformed 1,3,4-oxadiazole ring, such as 2,5-bis(p-aminophenyl)-1,3,4-oxadiazole, 2,5-bis[p-(4-aminophenoxy)phenyl]-1,3,4-oxadiazole, 2,5-bis[p-(3-aminophenoxy)phenyl]-1,3,4-oxadiazole, 2-(4-dimethylaminophenyl)-5-(3,5-diaminophenyl)-1,3,4-oxadiazole and 2-(4-fluorophenyl)-5-(3,5-diaminophenyl)-1,3,4-oxadiazole, with an aromatic dianhydride incorporating ether linkages and hexafluoroisopropylidene group, namely 1,1,1,3,3,3-hexafluoro-2,2-bis-[(3,4-dicarboxyphenoxy)phenyl]-propane dianhydride. The polymers were easily soluble in polar organic solvents, such as N-methylpyrrolidinone, N,N-dimethylformamide, and pyridine, as well as in certain low boiling-point organic solvents, such as tetrahydrofuran and chloroform. Very thin coatings deposited onto silicon wafers exhibited smooth, pinhole-free surface in atomic force microscopy. The polymers showed high thermal stability with decomposition temperature being above 410 °C. They exhibited a glass transition in the temperature range of 183-217 °C, with reasonable interval between glass transition and decomposition temperature. Solutions of some polymers in N,N-dimethylformamide exhibited blue fluorescence, having maximum emission wavelength in the range of 411-424 nm.     

1,2,3-Triazolium-based poly(acrylate ionic liquid)s

Nitroxide-mediated radical polymerization of a tailor-made acrylate carrying a 1,2,3-triazole group with an undecanoyl spacer affords a well-defined (M_n = 7860 g mol⁻¹ and D = 1.39) neutral polyacrylate precursor. A series of 1,2,3-triazolium-based poly(ionic liquid)s (TPILs) is then obtained by straightforward quaternization of the 1,2,3-triazole groups with methyl iodide and subsequent anion metathesis reactions. Among the prepared materials, TPIL with bis(trifluoromethane)sulfonimide anion exhibits low glass transition temperature (T_g = −40 °C), high thermal stability (T_d10 = 325 °C) and anhydrous ionic conductivity of 4 × 10⁻⁶ S cm⁻¹ at 30 °C, as measured by differential scanning calorimetry, thermogravimetric analysis and broadband dielectric spectroscopy, respectively.     

Characterization and property correlations of amorphous poly(alpha olefin)

Amorphous poly(alpha olefins)® (APAOs) with various types and contents of comonomers, and molecular weight were characterized by general, thermal, rheological, and mechanical methods and their properties were correlated with their molecular parameters. It was found that they can be used as a modifier for isotactic polypropylene. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Synthesis and characterization of hyperbranched poly(silyl ester)s

Hyperbranched poly(silyl ester)s were synthesized via the A₂ + B₄ route by the polycondensation reaction. The solid poly(silyl ester) was obtained by the reaction of di‐tert‐butyl adipate and 1,3‐tetramethyl‐1,3‐bis‐β(methyl‐dicholorosilyl)ethyl disiloxane. The oligomers with tert‐butyl terminal groups were obtained via the A₂ + B₂ route by the reaction of 1,5‐dichloro‐1,1,5,5‐tetramethyl‐3,3‐diphenyl‐trisi1oxane with excess amount of di‐tert‐butyl adipate. The viscous fluid and soft solid poly(silyl ester)s were obtained by the reaction of the oligomers as big monomers with 1,3‐tetramethyl‐1,3‐bis‐β(methyl‐dicholorosilyl)ethyl disiloxane. The polymers were characterized by ¹H NMR, IR, and UV spectroscopies, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The ¹H NMR and IR analysis proved the existence of the branched structures in the polymers. The glass transition temperatures (T_g's) of the viscous fluid and soft solid polymers were below room temperature. The T_g of the solid poly(silyl ester) was not found below room temperature but a temperature for the transition in the liquid crystalline phase was found at 42°C. Thermal decomposition of the soft solid and solid poly(silyl ester)s started at about 130°C and for the others it started at about 200°C. The obtained hyperbranched polymers did not decompose completely at 700°C. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3430–3436, 2006     

Thermally induced hydrogel formation in aqueous solutions of poly(N-isopropylacrylamide) and fluorocarbon-modified poly(oxyethylene)s

A number of perfluorooctyl-modified poly(oxyethylene)s (F_QPEOs) of molar masses of approximately 2000 and 4000 were synthesised using a two-step procedure: (a) preparation of PEO precursors bearing tertiary amino groups (NPEOs) and (b) their quaternisation with perfluorooctyl iodide to obtain one-ended (F_QE_n), telechelic (F_QE_nF_Q) or PEO modified with a C₈F₁₇-group in the mid of the polyether chain (E_nF_QE_n). F_Q is abbreviation of the C₈F₁₇-group attached to a PEO chain (E_n) through a quaternary ammonium group. The aqueous solution properties of F_QPEOs were studied by viscosity measurements at 25 °C. The cationic charge affects the association ability of the F_Q group and the one-ended F_QE_n behaves like PEO modified with a C₆F₁₃-group through urethane linkage. Temperature induced interactions in aqueous mixtures of F_QPEOs with poly(N-isopropylacrylamide) (PNIPAM) were studied by turbidity and rheological measurements. In the semi-dilute regime, the aqueous polymer mixtures exhibit a large viscosity enhancement upon heating as soon as the temperature reaches 35 °C. In the range from 35 to 40 °C the mixtures of PNIPAM with F_QE_n and E₅₀F_QE₅₀ form gels with viscoelastic response. The solution of PNIPAM mixed with the telechelic F_QE₁₀₀F_Q reveals shear-thickening at 35 and 40 °C.