新型聚醚聚氨酯/硬段模型化合物/高氯酸钠复合物的制备和表征

以聚醚聚氨酯和硬段模型化合物为聚合物基体,高氯酸钠为掺杂盐,合成了一系列新型的聚氨酯／硬段模型化合物／高氯酸钠复合物,利用FR－IR,DSC,AFM和复阻抗谱等表征手段对其形态和性能进行了基团和羰基都可与钠离子进行络合,温度变化可以导致不同程度的络合,在低盐浓度下,复合物的Tk随盐浓度的增加逐渐上升,而在一定的浓度之上,玻璃化转变温度又明显下降;通过调整盐的含量可以得到不同的表面形态。随着温度的升高,该体系的离子电导率显著增加。     

Characteristic ratio of poly(tetrahydrofurfuryl acrylate) and poly(2-ethylbutyl acrylate)

The synthesis, characteristic ratio C_∞ and glass transition temperature (T_g) of poly(tetrahydrofurfuryl acrylate) (PTHFA) and of poly(2-ethylbutyl acrylate) (P2EBA) are reported. P2EBA has slightly lower flexibility (C_∞ = 9.2) than PTHFA (C_∞ = 8.6), mainly because of the higher bulkiness of its side group and the closer proximity to the main chain. The C_∞ results compared with the corresponding polymethacrylates show an increase in flexibility due to the absence of the α-methyl group. Comparison with poly(methyl acrylate) clearly shows the influence of the bulkiness of the side group on the chain flexibility. The lower T_g of P2EBA than that of PTHFA may be explained by the higher flexibility of the 2-ethylbutyl side group. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 1589–1592, 1997     

Poly(urethane Methacrylate) Thermo-Setting Resins Studied by Thermogravimetry and Thermomechanical Analysis

Two different poly(urethane acrylate) resins (one with a trimer: PUA1, the second with a dimer: PUA2) prepared [1] by photo curing reaction are investigated by means of thermogravimetry and thermomechanical measurements. The lack of mass loss found up to 300°C for both systems shows their good thermal stability. Beyond this temperature, two mass losses occur consecutively. This mass loss already studied by TG-FTIR coupled measurements for PUA1 resin has been attributed to the degradation of carbonyl groups [1]. The extension to PUA2 and the comparison between the mass loss magnitude and the relative contain in acrylate of the resins leads to attribute the first degradation to the degradation of the acrylate fraction. The degradation of dimer based resin occurs earlier and with a faster kinetic than the trimer based resin. The variations of linear expansion and penetration coefficients measured by thermomechanical analysis (penetration probe) in the glassy state and in the glass transition temperature domain (the onset glass transition temperatures measured by DSC at 20°C min^–1 are respectively equal to 111 and 107°C for PUA1 and PUA2, the transitions, not well defined, extending over 30°C), show that despite of a weaker compactness, the trimer based resin is more rigid than the dimer one. This revised version was published online in August 2006 with corrections to the Cover Date.     

Enhanced mobility and increased gas sorption capacity in thin film and nanoconduit confined polymers

Poly(tert butyl acrylate) (PTBA) is found to exhibit enhanced mobility when spun cast into thin films or impregnated into cylindrical anodic aluminum oxide (AAO) nanoscale pores. In a thin film configuration, the glass transition temperature of 20 nm thick PTBA is found to decrease almost 20 °C compared to the bulk. Consistent with this mobility increase, an increased volume fraction of interphase polymer leads to at least a 2.4 times viscosity reduction when PTBA is impregnated in 100 nm pores versus 200 nm pores. Such increases in mobility result in a 15‐fold increase in CO₂ permeability for an AAO confined geometry compared to a bulk film. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 434–441, 2010     

Diffusion in glassy polymers

Two versions of the free‐volume theory of diffusion are compared by considering differences in the predictions for the activation energy for the diffusion process. A number of data‐theory comparisons for free‐volume theory are discussed and evaluated. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 785–788, 2003     

Holographic grating relaxation studies of probe diffusion in amorphous polymers

Probe diffusion of camphorquinone, thymoquinone, and diacetyl in polymers was studied by the laser-induced holographic grating relaxation (HGR) technique in polymers. The effects of changing the probe size and various parameters of the polymer, such as the molecular weight, chain conformation, and the glass transition temperature, on the probe diffusion coefficient have been investigated. Furthermore, effects of cross-linking and plasticizing the chains of the polymer host on the probe diffusion coefficient were also studied. Temperature-dependent studies show that except for the very low molecular weight poly(methyl methacrylate), all probe diffusion coefficient data above the glass transition temperature fit well to the WLF equation. ©1995 John Wiley & Sons, Inc.     

Mechanical properties and morphology of epoxy/poly(vinyl acetate)/poly(4-vinyl phenol) brominated system

Diglycidyl ether of bisfenol-A (DGEBA)/poly(vinyl acetate) (PVAc)/poly(4-vinyl phenol) brominated (PVPhBr) ternary blends cured with 4,4’-diaminodiphenylmethane (DDM) were investigated by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA) and scanning electron microscopy (SEM). Homogeneous (DGEBA+DDM)/PVPhBr networks with a unique T _g are generated. Ternary blends (DGEBA+DDM)/PVAc/PVPhBr are initially miscible and phase separate upon curing arising two T _gs that correspond to a PVAc-rich phase and to epoxy network phase. Increasing the PVPhBr content the T _gof the PVAc phase move to higher temperatures as a consequence of the PVAc-PVPhBr interactions. Different morphologies are generated as a function of the blend composition.     

The mechanical and thermal behaviors of glass bead filled polypropylene

Notch Izod impact strength of poly(propylene) (PP)/glass bead blends was studied as a function of temperature. The results indicated that the toughness for various blends could undergo a brittle‐ductile transition (BDT) with increasing temperature. The BDT temperature (T_BD) decreased with increasing glass bead content. Introducing the interparticle distance (ID) concept into the study, it was found that the critical interparticle distance (ID_c) reduced with increasing test temperature correspondingly. The static tensile tests showed that the Young's modulus of the blends decreased slightly first and thereafter increased with increasing glass bead content. However, the yield stress decreased considerably with the increase in glass bead content. Dynamic mechanical analysis (DMA) measurements revealed that the heat‐deflection temperature of the PP could be much improved by the incorporation of glass beads. Moreover, the glass transition temperature (T_g) increased obviously with increasing glass beads content. Differential scanning calorimetry (DSC) results implied that the addition of glass beads could change the crystallinity as well as the melting temperature of the PP slightly. Thermogravimetric analysis (TGA) measurements implied that the decomposition temperature of the blend could be much improved by the incorporation of glass beads. Copyright © 2004 John Wiley & Sons, Ltd.     

Side‐chain crystallization behavior of graft copolymers consisting of amorphous main chain and crystalline side chains: Poly(methyl methacrylate)‐graft‐poly(ethylene glycol) and poly(methyl acrylate)‐graft‐poly(ethylene glycol)

Graft copolymers consisting of amorphous main chain, poly(methyl methacrylate) (PMMA), or poly(methyl acrylate) (PMAc), and crystalline side chains, poly(ethylene glycol) (PEG), have been prepared by copolymerization of PEG macromonomers with methyl methacrylate or methyl acrylate (MMAx or MACx, respectively). Because of the compatibility of PMMA/PEG and PMAc/PEG, from small‐angle X‐ray scattering results, the main and side chains in graft copolymers were suggested to be homogeneous in the molten state. Differential scanning calorimetry (DSC) cooling scans revealed that PEG side chains for graft copolymers with large PEG fractions were crystallized when the sample was cooled, with a cooling rate of 10 °C/min. The spherulite pattern observed by a polarized optical microscope suggested the growth of PEG crystalline lamellae. Crystallization of PEG in MMAx was more restrained than in MACx. From these results, we have concluded that the crystallization behavior of the grafted side chains is strongly influenced by the glass transition of a homogeneously molten sample as well as dilution of the crystallizable chains. Domain spacings for isothermally crystallized graft copolymers were described by interdigitating chain packing in crystalline–amorphous lamellar structure. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 79–86, 2005     

Preparation and thermal properties of asymmetrically substituted poly(silylenemethylene)s

Poly(silylenemethylene)s of the types [SiMeRCH₂]_n and [SiHRCH₂]_n were prepared by the ring-opening polymerization (ROP) of 1,3-disilacyclobutanes (DSCBs) containing n-alkyl substituents, such as C₂H₅, n-C₃H₇, n-C₄H₉, n-C₅H₁₁, and n-C₆H₁₃, or a phenyl group on the Si. These new polymers include a monosilicon analog of poly(styrene), [SiHPhCH₂]_n. Improved synthesis routes to the DSCB monomers were developed which proceed through Grignard ring closure reactions on alkoxy-substituted chlorocarbosilanes. All of these asymmetrically substituted polymers were obtained in high molecular weight form, except for [SiHPhCH₂]_n. The configurations of all of the polymers were found to be atactic. The aryl-substituted polymers have higher glass transition temperatures (T_gs) and thermal stability than those of the alkyl-substituted poly(silylenemethylene)s. Unlike the polyolefins of the type [C(H)(R)CH₂]_n, where T_g drops continuously from R = Me to n-Hex, the T_gs of the n-C_nH_2n+1 (n = 2–6)-substituted [SiMeRCH₂]_n PSM's appear to reach a maximum (at −61°C) for the R = n-Pr-substituted polymer. Moreover, where it was possible to make direct comparisons among similarly substituted atactic polymers, all of the poly(silylenemethylene)s were found to have lower T_gs than their all-carbon analogs. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3193–3205, 1997     

Understanding the effect of skin formation on the removal of solvents from semicrystalline polymers

The effect of glassy skin formation on the drying of semicrystalline polymers was investigated with a comprehensive mathematical model developed for multicomponent systems. Polymers with high glass‐transition temperatures can become rubbery at room temperature under the influence of solvents. As the solvents are removed from the polymer, a glassy skin can form and continue to develop. The model takes into account the effects of diffusion‐induced polymer crystallization as well as glassy–rubbery transitions on the overall solvent content and polymer crystallinity. A Vrentas–Duda free‐volume‐based diffusion scheme and crystallization kinetics were used in our model. The polymer–solvent system chosen was a poly(vinyl alcohol) (PVA)–water–methanol system. The drying kinetics of PVA films were obtained by gravimetric methods with swollen films with known water/methanol concentrations. The overall drying behaviors of the polymer system determined by our model and experimental methods were compared and found to match well. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3191–3204, 2005     

Degradation of a poly(ester urethane) elastomer. I. Absorption and diffusion of water in Estane® 5703 and related polymers

In preparation for studying the hydrolytic degradation of Estane® 5703 and related poly(ester urethane) elastomers, the absorption (solubility) and diffusion of water in these polymers have been examined experimentally and modeled theoretically. Weight gain and loss experiments have been carried out. The amount of water absorbed per gram of sample was linear at low relative humidities (RHs) but curved upward at higher RHs. This curvature was not fit by Henry's law or the Flory–Huggins equation but was easily fit by a water‐cluster model. Diffusion coefficients were determined by fitting the time dependence of the sample weights, and the diffusion appeared Fickian to within experimental uncertainty. The similarity of related polymers was used to determine the approximate temperature dependence of the absorption. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 40: 181–191, 2002     

Ionic conductivity of complexes of novel multiarmed polymers with phosphazene core and LiClO4

Novel multiarmed polymers with ethylene oxide units, [( CH₂CH₂O)_n : 7, n = 3; 8, n= 7.2; 9, n = 11.8, and 12, n = 11.8] were prepared from the reaction of polyethylene glycol monomethyl ethers with acid chlorides of hexakis(3,5-dicarboxyphenoxy)-( 6 ) and hexakis(4-carboxyphenoxy)cyclotriphosphazenes ( 11 ) and conductivities of their Li⁺ salt complexes were investigated. The glass transition temperatures of the salt-free polymers are in the temperature range −59 to −54°C, indicative of a high degree of reorientational mobility of the arms. When LiClO₄ was added to the multiarmed polymers, the T_g values raised monotonically. The extent of T_g elevation was affected by the length of arms and the number of oxygen atoms around cyclotriphosphazene core and increased in the order 7 > 8 > 12 > 9 . The conductivities increased in the order 9 > 8 = 12 > 7 and the maximum conductivities of 4.0 × 10⁻⁵ S/cm at 30°C and 6.0 × 10⁻⁴ S/cm at 90°C have been achieved for the 9 -Li⁺ complex with Li⁺/O = 0.03. Interestingly, the conductivity of 9 -Li⁺ complexes at constant reduced temperatures increased in the whole concentrations of LiClO₄ examined (Li⁺/O = 0.01–0.2), although the degree of increase in conductivity above Li⁺/O = 0.06 became small. From the behaviors of T_g and the conductivity of multiarmed polymer–LiClO₄ complexes, it appears that the conductivity is governed by relative concentrations of inter- and intramolecular complexes in the polymer matrix. The influence of structural change of the comb-shaped to multiarmed polymers on the conductivity is described. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 1839–1847, 1997     

Glass transition,crystallization, and morphology relationships in miscible poly(aryl ether ketones) and poly(ether imide) blends

The relationships among glass transition, crystallization, melting, and crystal morphology of poly(aryl ether ketone) (PAEK)/poly(other imide) (PEI) blends was studied by thermal, optical and small-angle x-ray scattering (SAXS) methods. Two types of PAEK were chosen for this work: poly(aryl ether ether ketone), PEEK, and poly(aryl ether ketone ketone), PEKK, which have distinctly different crystallization rates. Both PAEKs show complete miscibility with PEI in the amorphous phase. As PAEK crystallizes, the noncrystallizable PEI component is rejected from the crystalline region, resulting in a broad amorphous population, which was indicated by the broadening and the increase of T_g over that of the purely amorphous mixture. The presence of the PEI component significantly decreases the bulk crystallization and crystal growth rate of PAEK, but the equilibrium melting temperature and crystal surface free energies are not affected. The morphology of the PEI segregation was investigated by SAXS measurements. The results indicated that the inter(lamellar-bundle) PEI trapping morphology was dominant in the PEEK/PEI blends under rapid crystallization conditions, whereas the interspherulitic morphology was dominant in the slow crystallizing PEKK/PEI blends. These morphologies were qualitatively explained by the expression δ=D/G, where G was the crystal growth rate and D was the mutual diffusion coefficient. © 1993 John Wiley & Sons, Inc.     

Finite difference modeling of the gas transport process in glassy polymers

Finite difference modeling has been used to predict the results of gas transport experiments for a concentration-dependent diffusion coefficient. Experiments on the transport of CO₂ in poly(ethylene terephthalate) and poly(ethylene naphthalate) had previously shown a difference between the effective diffusion coefficients for absorption and desorption runs of a double-sided experiment, but this effect had not been seen for single-sided experiments. The finite difference calculations show that such results are to be expected, and the parameters included in the models that attempt to describe the diffusion process in glassy polymers, such as the dual-mode model, and which lead to concentration-dependent diffusion coefficients, can be found by fitting the experimental data for the double-sided experiment using finite difference modeling. The dependence of the effective diffusion coefficient on pressure for the single-sided experiment can be correctly predicted using results from the double-sided experiment for an identical sample. © 1996 John Wiley & Sons, Inc.     

The size and number of local free volumes in polypropylenes: A positron lifetime and PVT study

The temperature dependence of the mean size of local free volumes in an amorphous atactic (aPP) and a semicrystalline syndiotactic polypropylene (sPP), and an amorphous ethylene‐propylene copolymer (E‐co‐P48) has been studied. Pressure‐volume‐temperature (PVT) experiments were performed for aPP, from which the hole fraction h of the Simha‐Somcynsky theory and the number density of holes were estimated. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 3089–3093, 2003     

Epoxy/poly(benzyl methacrylate) blends: miscibility, phase separation on curing and morphology

Diglycidyl ether of bisfenol-A (DGEBA)/polybenzyl methacrylate (PBzMA) blends cured with 4,4’-diaminodiphenylmethane (DDM) were studied. Miscibility, phase separation, cure kinetics and morphology were investigated through differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Non-reactive DGEBA/PBzMA blends are miscible over the whole composition range. The addition of PBzMA to the reactive (DGEBA+DDM) mixture slows down the curing rate, although the reaction mechanism remains autocatalytic. On curing, initially miscible (DGEBA+DDM)/PBzMA blends phase separate, arising two glass transition temperatures that correspond to a PBzMA-rich phase and to epoxy network. Cured epoxy/PBzMA blends present different morphologies as a function of the PBzMA content.     

DSC study of the miscibility of poly(methyl acrylate)-polystyrene sequential interpenetrating polymer networks

The phenomenon of forced compatibilization has been studied in poly(methyl acrylate)-polystyrene PMA-i-PS sequential interpenetrating polymer networks, IPNs, using differential scanning calorimetry. Both networks in the IPN were prepared using the same amount of ethylene glycol dimethacrylate, EGDMA, as crosslinking agent. The samples were subjected to thermal treatments which included annealing at different ageing temperatures T _a, for 300 min. From the DSC curves, recorded on heating the enthalpy loss during the isothermal annealing, Δh _a was calculated. The dependence of Dh _a with the annealing temperature was used to define the temperature interval in which the conformational mobility is significant. The comparison of the Δh _a(T _a) curves obtained in an IPN and the results obtained with the pure component homo-networks with the same crosslinking density reveal some details of the miscibility of the IPN. In the case of the IPN crosslinked with 10% EGDMA, two peaks are apparent in the Δh _a(T _a) curve, but the high-temperature peak is shifted towards lower temperatures compared to that of the polystyrene network while the low-temperature one is nearly at the same temperature than the one of the poly(methyl acrylate) homonetwork. This means that compatibilization is not complete and phase separation still exists even at this high crosslinking density. The different behaviour of the high and low temperature transitions can be explained by the dynamic heterogeneity of the sample, i.e. by the different length of cooperativity of the conformational rearrangements of PMA and PS domains at any temperature. This revised version was published online in July 2006 with corrections to the Cover Date.     

Order in amorphous di‐n‐alkyl itaconate polymers,copolymers, and blends

The presence of a main‐chain correlation distance (d_II) in the poly(di‐n‐alkyl itaconate)s was confirmed with small‐angle X‐ray scattering/wide‐angle X‐ray scattering measurements taken over the temperature range of 293–478 K. Data for a series of alkyl acrylate polymers were also obtained for comparison. The intensity of the itaconate d_II peak was significant and indicated a greater level of nanophase formation than in analogous systems. In the lower members of the series, nanophase formation appeared to be further enhanced in the temperature range above the glass‐transition temperature (T_g). This was ascribed to the rapidly increasing main‐chain mobility in this region. Macroscopically phase‐separated itaconate blends displayed the individual d_II nanospacings of each homopolymer component. Copolymers, on the other hand, showed more interesting behavior. Poly(methyl‐co‐di‐n‐butyl itaconate) followed an average behavior in which the d_II spacing and T_g changed progressively with the comonomer content. In contrast, the side‐chain pairing in poly(methyl‐co‐di‐n‐octyl itaconate) generated d_II spacings characteristic of separate methyl and octyl nanodomains. The observation of the dioctyl nanodomains, along with the dioctyl side‐chain lower T_g relaxation event, confirmed the concept of independent side‐chain‐domain relaxation in these polymers. The temperature behavior of the poly(methyl‐co‐di‐n‐octyl itaconate) small‐angle X‐ray scattering profiles and scattering correlation lengths indicated that the two nanodomains were not completely structurally independent. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4000–4016, 2004     

A3‐type star polymers via click chemistry

We report a simple preparation of three‐armed (A₃‐type) star polymers based on the arm‐first technique, using a click‐reaction strategy between a well‐defined azide‐end‐functionalized polystyrene, poly(tert‐butyl acrylate), or poly(ethylene glycol) precursor and a trisalkyne‐functional initiator, 1,1,1‐tris[4‐(2‐propynyloxy)phenyl]ethane. The click‐reaction efficiency for A₃‐type star formation has been investigated with gel permeation chromatography measurements (refractive‐index detector). The gel permeation chromatography curves have been split with the deconvolution method (Gaussian area), and the efficiency of A₃‐type star formation has been found to be 87%. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6458–6465, 2006