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1.
A versatile nonaqueous emulsion polyaddition process for the one-step fabrication of spherical polyurethane nanoparticles
is presented. Three different emulsion systems were used consisting of N,N′-dimethylformamide (DMF) dispersed in n-hexane, acetonitrile dispersed in cyclohexane, and acetonitrile dispersed in tetradecane. After successful stabilization
of the emulsion systems by using a poly(isoprene)-poly(methylmethacrylate) block copolymer, the fabrication of the polyurethanes
was carried out within the dispersed polar phase. The polyurethane particles showed average diameters as small as 35 nm. Additionally,
infrared (IR) characterization revealed that the formation of any urea, which decreases the mechanical properties of the polyurethanes,
was prevented during the polyaddition. This was attributed to the anhydrous reaction conditions. Gel permeation chromatography
(GPC) analysis demonstrated the average molecular weights (M
n) of the polyurethanes to be as high as 16,500 g/mol, corresponding to conversions of 0.98. Comparable molecular weights and
conversions have not previously been achieved without the formation of urea. 相似文献
2.
Novel family of highly soluble polymers containing 3.3′-bicarbazolyl moieties is reported. Utilizing simple and efficient chemical oxidation of carbazole and its derivatives by iron trichloride exclusively and quantitatively yields the bicarbazolyl dimmers with reactive oxirane groups. The polymers were prepared in polyaddition reaction of bicarbazolyl-containing diepoxydes with 4,4′-thiobisbenzenethiol, 2,5-dimercapto-1,3,4-thiadiazole, or 1,3-benzenedithiol in the presence of catalyst triethylamine. Obtained compounds were characterized using GPC, DSC, IR, UV, fluorescence and 1H NMR spectroscopy. The hole drift mobility reaches 10−4 cm2/Vs at high electric fields. Such processable polymers with conjugated-nonconjugated repeating units in the main chain and good charge carrier mobility are quite promising for fabrication of optoelectronic devices. 相似文献
3.
Vytautas Getautis Maryte Daskeviciene Tadas Malinauskas Vygintas Jankauskas 《Monatshefte für Chemie / Chemical Monthly》2007,138(4):277-283
Summary. Synthesis of a new monomer and polymer containing both ferrocene and hydrazone moieties are reported. The obtained materials
were examined by various techniques including differential scanning calorimetry, UV, IR, NMR spectroscopy, and time of flight
method. These materials may be of particular interest for the development of future electrophotographic photoreceptors as
electron photoemission spectra of the layers showed ionization potentials of 5.35–5.41 eV. The hole drift mobility values
in compositions of the designed structures with bisphenol Z polycarbonate exceeded 10−8 cm2/Vs at strong electric fields. 相似文献
4.
Radical polyaddition of bis(α-trifluoromethyl-β,β-difluorovinyl) terephthalate [CF2C(CF3)OCOC6H4COOC(CF3)CF2] (BFP) with silsesquioxanes was investigated in order to produce a polymer possessing silsesquioxane moiety in polymer main chain. 1,3,5,7,9,11,13,15-octakis(dimethylsilyloxy)pentacyclo[9.5.1.13,9.15,15.17,13]octasiloxane (T8S) with BFP successfully afforded a polymer bearing a molecular weight of about 2.5×105. The polymer obtained were soluble in usual organic solvent such as methanol, tetrahydrofuran and chloroform. In order to get some information on the polyaddition reaction mechanism, model reactions of 2-benzoxypentafluoropropene [CF2C(CF3)OCOC6H5] (BPFP) with dimethylphenylsilane, [(CH3)2SiHC6H5], BPFP with 1,1,3,3-tetramethyldisiloxane {[(CH3)2SiH]2O}, and BFP with dimethylphenylsilane were carried out. The mechanism that the radical abstracts a hydrogen from silane compounds followed by the addition of perfluoroisopropenyl groups was proposed. 相似文献
5.
Yong-Zhong Du Jia-Guo Xu Ling Wang Hong Yuan Fu-Qiang Hu 《European Polymer Journal》2009,45(5):1397-1622
Nimodipine loaded hydroxypropyl-β-cyclodextrin polymeric nanocapsules were prepared by interfacial polyaddition of hydroxypropyl-β-cyclodextrin and isophorone diisocyante in a miniemulsion system. The effects of ultrasonicate times on the preparation of miniemulsion, the total amount of hydroxypropyl-β-cyclodextrin and isophorone diisocyante, and the molar ratio of isophorone diisocyante to hydroxypropyl-β-cyclodextrin on the capsule size and drug release behavior from capsule were investigated. The chitosan based polymeric nanocapsules were prepared as a control to study the effect of hydroxypropyl-β-cyclodextrin molecules in capsule matrix on the drug release. The results indicated that the droplet size of miniemulsion and capsule size decreased with increasing sonicate times. When the total amount of hydroxypropyl-β-cyclodextrin and isophorone diisocyante, and the molar ratio of isophorone diisocyante to hydroxypropyl-β-cyclodextrin were increased, the capsule as well, but the drug release rates from capsules became slower. The drug release behaviors from hydroxypropyl-β-cyclodextrin polymeric nanocapsules were affected by the drug diffusion through the polymer matrix and the formation of inclusion complex between drug and hydroxypropyl-β-cyclodextrin. 相似文献
6.
Hirotada Fujiwara Tadashi Narita Hiroshi Hamana 《Journal of fluorine chemistry》2004,125(10):1461-1464
The structure of the addition reaction product of 2-benzoxypentafluoropropene [CF2 = C(CF3)OCOC6H5] with 1,4-dioxane was investigated by the crystallographic analysis of the single crystal to conclude that the 2,6-disubstitution of 1,4-dioxane took place, on the contrary to the assumption that the reaction would take place at the 2- and 5-positions based on the product structure of 2-benzoxypentafluoropropene with tetrahydrofuran. Modified polyaddition reaction mechanism of bis(α-trifluoromethyl-β,β-difluorovinyl) terephthalate [CF2 = C(CF3)OCO-C6H4-COOC(CF3) = CF2] with 1,4-dioxane including 1,5-radical shift mechanism is proposed. 相似文献
7.
Xiao-Song Huang 《Journal of fluorine chemistry》2008,129(11):1076-1082
A novel and more reliable synthetic route to 2,5-difluoroterephthalic acid was developed. A series of new poly(hydroxyether terephthalate) were prepared by the polyaddition of 2,5-difluoroterephthalic acid with various aromatic bis(epoxide)s catalyzed by tetrabutyl ammonium bromide. 相似文献
8.
Boris Jaffrennou Françoise Méchin Jean-Pierre Pascault 《European Polymer Journal》2008,44(11):3439-3455
Poly[Styrene-b-Butadiene-b-(Methyl Methacrylate)], SBM triblock copolymers have been incorporated in different polyurethane, PU formulations in order to prepare nanostructured materials. Macrodiols used for PU synthesis were based on a central bis-phenol A, BPA unit with two hydroxyl-terminated oligo(oxypropylene), BPA-POx or oligo(oxyethylene), BPA-EO chains with varying lengths. The initial solubility of the three blocks and the rheological behavior of the solutions in macrodiols and also in two diisocyanates, isophorone diisocyanate, IPDI, and 1,3-xylylene diisocyanate, XDI have been first characterized. The PMMA block is the most soluble and its role during the reaction is to stabilize the initial nanostructure or to control the reaction-induced microphase separation.Block copolymers can be dissolved first in the macrodiol, or preferably in the diisocyanate. With BPA-POx and low SBM content (<10 wt%), transparent linear or crosslinked PU with well dispersed triblock nanoparticles have been prepared, depending on the molar mass of the macrodiol and on the concentration of diblock SB impurities present in the triblock. For high SBM concentrations (>50 wt%), a twin screw extruder had to be used for the blending. Under well-defined conditions, transparent linear PUs and linear segmented polyurethane-ureas have been prepared.This study confirms that for designing a nanostructured material from a reactive mixture with a triblock additive, one block, called “the nanostructuring block” has to remain soluble up to the end of the reaction. 相似文献
9.
V. Getautis J.V. Grazulevicius T. Malinauskas J. Sidaravicius 《European Polymer Journal》2007,43(8):3597-3603
The novel family of hole-transporting polymers containing hydrazone moieties is reported. The polymers were prepared in polyaddition reaction of dihydrazone-containing diepoxides with bifunctional nucleophilic linking agents in the presence of catalyst triethylamine. Obtained polymers were found to constitute novel polymeric hole transporting materials characterized by differential scanning calorimetry and time of flight method. The highest hole drift mobility in the newly synthesized polymers exceed 10−5 cm2 V−1 s−1 at an electric field of 106 V cm−1. 相似文献
10.
By using diphenyliodonium salts with different counterions as photo acid generators (PAGs), theeffect of acidity on ring-opening polymerization of epoxy monomers and polycondensation of polyol withhexamethoxymethyl melamine (HMMM) was studied. The result shows that the rate of ring-openingpolymerization is evidently dependent on the acidity of the acid and strong photo-generated acid is required.However, there is a leveling effect in the polycondensation system; if the photo-generated acid is strongerthan protonated HMMM, the acidity does not obviously affect the polycondensation rate. 相似文献