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1.
A new class of liquid‐crystalline poly(ethylene imine)s (PEIs) having four differently substituted (? CN,? C4H9,? OCH3 and? NO2) azobenzene side‐chain groups attached through alkyl spacer groups were successfully synthesized using a solution polycondensation reaction. The synthesized polymers were characterized using differential scanning calorimetry, polarized optical microscopy and X‐ray diffraction. The photochemical, thermo‐optical and photo‐orientational behavior of the polymers were investigated in detail. Spin‐coated films of PEIs with azobenzene groups having? C4H9,? OCH3 and? NO2 substituents showed out‐of‐plane molecular orientation on annealing. Except for the PEI with an azobenzene group having ? NO2 substituent, all polymers exhibited good photoresponsive properties upon irradiation with UV and visible light. Films of PEIs with azobenzene side groups having? CN,? C4H9 and? OCH3 substituents showed reversible alignment behavior from random state to out‐of‐plane and from out‐of‐plane to random state on annealing and on irradiation with UV and non‐polarized visible light. The reversibility of the molecular orientation of PEIs from random state to out‐of‐plane and from out‐of‐plane to random state greatly depended on the substituent attached to the azobenzene side‐chain group. Copyright © 2010 Society of Chemical Industry  相似文献   

2.
Poly(4‐vinylpyridine)s (P4VPs) fully and partially quaternized with dialkyloxyterphenyl groups were synthesized and characterized. These new polymers developed both liquid‐crystalline (LC) properties and a light emission (luminescence) in the blue region. The mesomorphic behavior of the polymers was initially characterized by differential scanning calorimetry and polarizing optical microscopy and was further corroborated by X‐ray diffraction analyses. The X‐ray diffraction patterns showed in the low‐angles region several equidistant diffraction peaks (d001, d002, d003, …) and in the wide‐angles region a broad peak typical of nonordered mesophases. From d001 and the length of the monomers, we deduced that the molecular arrangement in the mesophase corresponded to a double‐layered stacking of molecules with mesogens tilted with respect to the smectic plane and the backbones sandwiched between. In this arrangement, the different parts of mesogens are segregated from one another in layered domains. The longer smectic periods observed for copolymers indicated that the nonsubstituted pyridine cycles were sandwiched between two smectic layers. The emission spectra of these polymers were characterized by a broad signal centered at 365 nm. The combination of LC properties with luminescence in the polymers is interesting for the preparation of thin films with aligned emitters, particularly for linearly polarized light emission. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011  相似文献   

3.
By polycondensation reactions, starting from α, ω‐bis(chloromethyl)polydimethylsiloxanes with different molecular weights and 2,6‐bis(4‐hydroxybenzylidene)cyclohexanone, new polyethers were obtained. The structure of resulting polymers was confirmed by IR and 1H‐NMR spectroscopy and their thermal properties and mesophase behavior were studied by TGA, DSC, and polarizing light microscopy. Depending on the length of the siloxane spacer, some of the obtained compounds exhibited thermotropic liquid‐crystalline properties. A possible smectic texture was investigated by X‐ray diffraction measurements at room temperature. A decrease of the transition temperatures values was observed as the spacer length increased. The photochemical behavior of the siloxane polyethers was studied by ultraviolet absorption spectroscopy. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3093–3099, 2003  相似文献   

4.
A series of new liquid crystalline copolymers, poly[((S)‐2‐methyl‐1‐butyl methacrylate)‐co‐(6‐(4‐(4‐cyanophenylazo)phenoxy)hexyl methacrylate)], with different contents of chiral units of 17, 36, 54 and 78 mol% were synthesized. The structures and properties of the copolymers were characterized and evaluated using infrared, 1H NMR and UV spectroscopy, differential scanning calorimetry, gel permeation chromatography and circular dichroism (CD). The CD results suggested that absorptions of azobenzene chromophores were observed in films of copolymer containing 17, 36 or 54 mol% chiral units, but not in the film of copolymer containing 78 mol% chiral units. Also, CD values of the copolymeric films decreased with increasing chiral content. After irradiation with linear polarized light at 442 nm, CD values were changed in all the copolymeric films, and the CD values increased with decreasing chiral content in a nonlinear way, while the photoinduced change of chirality of the copolymers increased in a linear way with decreasing chiral content. The results are discussed in terms of interactions between structures and chiroptical properties. Copyright © 2007 Society of Chemical Industry  相似文献   

5.
Two series of amphiphilic copolymers, poly(HPMA‐co‐MPAP) I–V with n = 0.05–0.29 of the molar ratio of MPAP and poly(HPMA‐co‐MPAH)‐I–V with n = 0.05–0.23 of the molar ratio of MPAH, were prepared by radical copolymerization of N‐(2‐hydroxypropyl) methacrylamide (HPMA) with azo‐monomers such as 4‐(4‐methoxyphenylazo) phenyl methacrylate (MPAP) and 6‐[4‐(4‐methoxyphenylazo) phenoxy] hexyl methacrylate (MPAH) using 2,2′‐azobisisobutyronitrile as an initiator. Self‐organization of these copolymers in water was confirmed by disappearance of the proton signal of the methoxyazobenzene in 1H‐NMR spectra measured in the solvent system of D2O and CD3OD. It was also found from the λmax, located near 344 nm, that azobenzene groups self‐organized to form the dimeric chromophore type of aggregate. The aqueous solutions of poly(HPMA‐co‐MPAP) and poly(HPMA‐co‐MPAH) exhibited the lower critical solution temperature (LCST) from at 68 to 40°C and from at 70 to 52°C in the dark state, respectively, with increasing the molar ratios of azo‐monomers. On the other hand, the LCST measured in the photostationary state showed the higher temperature by 2–4°C compared with that in the dark state. It was found that the adsorption of poly(HPMA‐co‐MPAP)‐V (n = 0.29) on polystyrene microspheres was photoregulated. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3056–3063, 2001  相似文献   

6.
This study describes the fabrication and properties of poly(vinylidene fluoride) (PVDF) filtration membranes modified by blending with ionic liquid block copolymer P(MMA‐b‐MEBIm‐Br), which is synthesized via reversible addition‐fragmentation chain transfer polymerization method. The attenuated total reflectance‐Fourier transform infrared spectroscopy and X‐ray photoelectron analyses reveal that the ionic liquid block copolymers are immobilized on PVDF membrane surface. The modified PVDF membrane exhibits excellent charged and antifouling properties because of the charged and hydrophilic properties of the copolymer. Scanning electron microscopy and atomic force microscopy also indicate the morphological characteristics of the membrane and demonstrate that the surface porous structure becomes denser after adding the copolymer. The data of filtration and the zeta potential of the membranes suggest that the charged properties of the ionic liquid block copolymers are mainly responsible for the improvement of the reversible fouling ratio and the decrease in the total fouling ratio of the membranes. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44751.  相似文献   

7.
8.
Monodispersed poly(styrene-co-4-vinylpyridine) [P(St-co-4VP)] microspheres were prepared by emulsifier-free emulsion polymerization. The chemical metal deposition was used to prepare magnetic P(St-co-4VP)Ni, and P(St-co-4VP)Co microspheres exhibited ferromagnetic properties. The morphology of P(St-co-4VP) and P(St-co-4VP)Ni or Co microspheres was studied by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Electron spectroscopy for chemical analysis (ESCA) and XRD were used to investigate the valence changement of metals in air. The magnetic properties of the magnetic microsphere were studied. The difference of soft magnetism between P(St-co-4VP)Ni and P(St-co-4VP)Co microspheres was discussed. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2307–2312, 1998  相似文献   

9.
在链转移剂S-十二烷基-S′-(α,α′-二甲基-α″-乙酸)-三硫代碳酸酯的调控下,偶氮二异丁腈引发单体2-乙烯基吡啶、苯乙烯和聚乙二醇单甲醚甲基丙烯酸酯连续聚合,制备了含有聚2-乙烯基吡啶(P2VP)、聚苯乙烯(PS)和聚(聚乙二醇单甲醚甲基丙烯酸酯)[P(POEGMA)]链段的三嵌段共聚物P2VP105-b-PS...  相似文献   

10.
Polystyrene‐block‐poly(4‐vinylpyridine) (PS‐b‐P4VP) was synthesized by two steps of reversible addition‐fragmentation transfer (RAFT) polymerization of styrene (St) and 4‐vinylpyridine (4VP) successively. After P4VP block was quaternized with CH3I, PS‐b‐quaternized P4VP/montmorillonite (PS‐b‐QP4VP/MMT) nanocomposites were prepared by cationic exchange reactions of quaternary ammonium ion in the PS‐b‐QP4VP with ions in MMT. The results obtained from X‐ray diffraction (XRD) and transmission electron microscopy (TEM) images demonstrate that the block copolymer/MMT nanocomposites are of intercalated and exfoliated structures, and also a small amount of silicates' layers remained in the original structure; differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) results show that the nanocomposites displayed higher glass transition temperature (Tg) and higher thermal stability than that of the corresponding copolymers. The blending of PS‐b‐QP4VP/MMT with commercial PS makes MMT to be further separated, and the MMT was homogeneously dispersed in the polymer matrix. The enhancement of thermal stability of PS/PS‐b‐QP4VP/MMT is about 20°C in comparison with commercial PS. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:1950–1958, 2006  相似文献   

11.
This mini‐review highlights issues related to the photo‐triggered macroscopic response of azopolymer in supramolecular hydrogel and polymer vesicles. Cyclodextrin (CD) can form an inclusion complex with trans‐azobenzene while cis‐azobenzene is expelled out of the CD's cavity. This photo‐reversible supramolecular host ? guest interaction is used to trigger sol ? gel transitions and to induce macroscopic assembly. When substituted azobenzene is located at chain ends of linear polyethylene glycol, monodisperse vesicles are formed exhibiting a photo‐induced pulsating behavior. The macroscopic phase transition and assembly or pulsating behavior of azopolymers can be expected to have potential applications as smart biomedical materials. © 2014 Society of Chemical Industry  相似文献   

12.
Blends of thermotropic liquid crystalline polymer (LCPA‐950), based on a copolyester of hydroxynapthoic acid and hydroxybenzoic acid with an engineering thermoplastic, poly(phenylene sulfide) (PPS), were prepared using a corotating twin‐screw extruder. Addition of a third component, a functionalized polypropylene (maleic anhydride grafted polypropylene, MA‐PP), that interact with the thermotropic liquid crystalline polymer (TLCP) facilitates the structural development of the TLCP phase by acting as a compatibilizer at the interface. Differential scanning calorimetry and dynamic mechanical thermal analysis results, however, show that there is an interaction between the polymers in the presence of compatibilizer. This means that MA‐PP can be used as a compatibilizer for the PPS/LCP in situ composite system. The viscosity of the compatibilized in situ composite was decreased by the compatibilizer, and this is mainly due to the fibrous structure of the LCP at the high shear rate. The mechanical properties of the ternary blends were increased when a proper amount of MA‐PP was added. This is attributed to fine fibril generation induced by the addition of MA‐PP. Morphological observations determined the significance of the third component in immiscible polymer blends, and an optimum amount of MA‐PP exists for the best mechanical performance. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007  相似文献   

13.
The UV‐vis absorption, thermal analysis, ionic conductivity, mechanical properties, and morphology of a blend of poly(dimethylsiloxane‐co‐ethylene oxide) [P(DMS‐co‐EO)] and poly(epichlorohydrin‐co‐ethylene oxide) [P(EPI‐co‐EO)] (P(DMS‐co‐EO)/P(EPI‐co‐EO) ratio of 15/85 wt %) with different concentrations of LiClO4 were studied. The maximum ionic conductivity (σ = 1.2 × 10?4 S cm?1) for the blend was obtained in the presence of 6% wt LiClO4. The crystalline phase of the blend disappeared with increasing salt concentration, whereas the glass transition temperature (Tg) progressively increased. UV‐vis absorption spectra for the blends with LiClO4 showed a transparent polymer electrolyte in the visible region. The addition of lithium salt decreased the tensile strength and elongation at break and increased Young's modulus of the blends. Scanning electron microscopy showed separation of the phases between P(DMS‐co‐EO) and P(EPI‐co‐EO), and the presence of LiClO4 made the blends more susceptible to cracking. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1230–1235, 2004  相似文献   

14.
The nonlinear optical response of the liquid crystalline multiarm star‐shaped azodendrimer was investigated in picosecond pulse and CW regimes at 532 nm. The polymer exhibited large nonlinear refractive coefficient in two regimes (n2 = −2.88 × 10−13 cm2/W and −1.1 × 10−10 cm2/W under picoseconds pulse excitation, whereas n2 = −1.4 × 10−6 cm2/W and n2 = −8.8 × 10−5 cm2/W under CW laser excitation in solution and film, respectively). The mechanism accounting for the process of nonlinear refraction was discussed. The value of photoinduced birefringence in the polymer film was also measured (Δn ∼ 10−3) under CW laser excitation at 532 nm. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011  相似文献   

15.
A series of side‐chain liquid crystalline oligomers (P1–P7) have been synthesized with cyclo(methylhydrogeno)siloxane and two cholesteric liquid crystalline monomers cholesteryl 4‐(10‐undecylen‐1‐yloxy)benzoate (M1) and cholesterol 4‐{6‐[(4‐(allyloxyl)‐benzoyl]‐hexanoxocarbonyl}‐benzoate (M2). The chemical structures and liquid crystalline properties of the synthesized oligomers were investigated using various experimental techniques such as FTIR, 1H‐NMR, DSC, POM, and XRD. All monomers and chiral oligomers show a cholesteric mesophase with very wide mesophase temperature ranges. They appear highly thermally stable with decomposition temperatures (Td) at 5% weight loss greater than 300°C. The optical properties of the oligmers have been characterized by reflection spectra and optical rotation analysis. All synthesized oligomers display colors at room temperature, and show reversible thermochromism within a wide temperature range (>120°C). The λmax values of the oligomers also nearly coincide during the first, second, and third heating cycles. The specific rotation of each oligomer is very sensitive to temperature, and the specific rotation value of P3 smoothly changes from ?21.7° to ?0.7° when it is heated. The optical properties of the oligomers offer tremendous potential for various optical applications. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1321‐1327, 2013  相似文献   

16.
A series of new cholesteric liquid‐crystalline polysiloxanes ( P1 – P5 ) derived from menthyl groups were synthesized. The chemical structures of the monomers and polymers were characterized with Fourier transform infrared, 1H‐NMR, 13C‐NMR, and elemental analyses. The mesomorphic properties and thermal behavior were investigated with differential scanning calorimetry, polarizing optical microscopy, thermogravimetric analysis, and X‐ray diffraction measurements. The influence of the polymer structure on the thermal behavior was discussed. The monomer diosgeninyl 4‐allyloxybenzoate exhibited a typical cholesteric oily‐streak texture and a focal‐conic texture. Polymers P1 – P5 showed thermotropic liquid‐crystalline properties. P1 displayed a smectic fan‐shaped texture, P2 – P5 showed a cholesteric Grandjean texture, and P6 and P7 did not show mesomorphic properties. The experimental results demonstrated that the glass‐transition temperature and the clearing temperature decreased, and the mesomorphic properties weakened with an increasing concentration of menthyl units. Moreover, P1 – P5 exhibited wide mesophase temperature ranges and high thermal stability. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:5559–5565, 2006  相似文献   

17.
Liquid crystalline diblock copolymers with different molecular weights and low polydispersities were synthesized by atom transfer radical polymerization of methyl methacrylate (MMA) and 2,5‐bis[(4‐methoxyphenyl)oxycarbonyl]styrene (MPCS) monomers. The block architecture (coil‐conformation of MMA segment and rigid‐rod of MPCS segment) of the copolymer was experimentally confirmed by a combination of 1H nuclear magnetic resonance and gel permeation chromatograph techniques. The liquid crystalline behaviour of the copolymer was studied using differential scanning calorimetry and polarized optical microscope. It was found that the liquid crystalline behaviour was dependent on the number average molecular weight of the rigid segment. Only those copolymers with Mn(GPC) of the rigid block above 9200 g mol?1 could form liquid crystalline phases higher than the glass transition temperature of the rigid block. The random copolymers MPCS‐co‐MMA were also synthesized by conventional free radical polymerization. The molar content of MPCS in MPCS‐co‐MMA had to be higher than 71% to maintain liquid crystalline behaviour. © 2003 Society of Chemical Industry  相似文献   

18.
Composites based on the polysulfone of bisfenol A (PSF) and a liquid‐crystalline copolyester (Rodrun 5000) were obtained by two processing methods, (1) direct injection moulding (DI) and (2) extrusion followed by injection moulding (PI), across the whole composition range. The blends were immiscible and showed two pure amorphous phases. The inferior mechanical properties of PI blends, and their more difficult processing, meant that the PI procedure is not suitable in these blends. The generally linear relationship of the Young's modulus of the DI blends is due to the counteracting effects of the large orientation of the skin and its low thickness. The improvement in notched impact strength of PSF on the addition of small amounts of LCP indicated an important reduction in its notch sensibility. The tensile strength behaviour was close to linearity, with the exception of the 20/80 blend in which it was synergistic. This had been seen in previous thermoplastic/LCP blends, and depicts a behaviour reminiscent of rubber‐toughened blends. Copyright © 2004 Society of Chemical Industry  相似文献   

19.
A ferroelectric side-chain liquid crystalline polysiloxane (FLCP) containing azobenzene dyes as guest molecules for electro-optics has been investigated. The intensity and frequency of the Goldstone mode for the FLCP were increased remarkably after doping with azobenzene dyes. Larger fluctuation of the spontaneous polarization vector in each smectic layer under an applied electric field can be brought about with the addition of a strong dipole-moment guest molecule. This leads to a larger spontaneous polarization and shorter response time. It was found that the doping of a suitable amount of a strong dipole-moment azobenzene dye in the LC phase of the FLCP is helpful for the improvement of the electro-optical properties.  相似文献   

20.
Palladium nanoparticles in the size range of 5–6 nm were prepared conveniently by reducing palladium(II) with atmospheric pressure hydrogen and stabilized by 2,2′‐dipyridylamine‐functionalized imidazolium cations according to our approach. The efficient catalytic conversion of cyclohexene into cyclohexane by the functionalized ionic liquid‐stabilized palladium nanoparticles has been performed under very mild hydrogen pressure (0.1 MPa) and at 35 °C. It was found that the concentration of palladium and the reaction temperature considerably affected the size and degree of aggregation of Pd nanoparticles in ionic liquid, which further changed the performance of the catalyst activity. The synthesized nanocatalysts can be recycled at least five times without any loss of the activity. Finally, the scope of substrates was also investigated. The excellent catalytic activity of the present system can be attributed to good stabilization and high dispersion of palladium nanoparticles.  相似文献   

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