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1.
Sebastian Mendrek Aleksandra Mendrek Hans-Juergen Adler Andrzej Dworak Dirk Kuckling 《Colloid and polymer science》2010,288(7):777-786
Temperature-sensitive poly(glycidol)-b-poly(N-isopropylacrylamide) block copolymers (PGl55PNIPAAmy) were synthesised and their aqueous solutions investigated by different methods including differential scanning calorimetry
(DSC), UV-VIS spectroscopy as well as dynamic and static light scattering. The cloud point temperature (T
c) depended on the composition of the investigated block copolymers and increased with decreasing length of the PNIPAAm block
in PGl55PNIPAAmy copolymers. In contrast, the enthalpy of phase separation of PNIPAAm segments measured by DSC decreased with decreasing length
of the PNIPAAm block in the polymer. These findings can be correlated with the behaviour of homo-PNIPAAm with similar molecular
weights indicating that the influence of PGl on the local environment and phase separation of PNIPAAm chains is similar to
the influence observed for PNIPAAm chains bearing different low molecular weight end group. Using DLS measurement, it was
shown that the aggregation process depended on the PGl/PNIPAAm block ratio. If the PGl/PNIPAAm ratio was low, stable core-shell
aggregates were formed. In contrast, the tendency to formation of large unstable, loose aggregates was observed for copolymers
with high PGl/PNIPAAm ratio. 相似文献
2.
含有不同的链长的w-吡咯烷基二甲基氯硅烷作为粘合剂通过自组装(SAMs)吸附于二氧化硅表面,然后聚吡咯膜化学沉积于该粘合剂修饰的表面。化学沉积的聚吡咯膜的表面形貌用扫描电镜(SEM)及原子力显微镜(AFM)表征。除短链外不同链长的粘合剂对聚吡咯膜的厚度影响不大。聚吡咯膜的电特性用电流-电压表征。结果显示电流与粘合剂的链长无关。电特性表明载流子迁移率为1.4 ´ 10-4 cm2×V-1.s –1。 相似文献
3.
Evelin Jaehne Thomas Kowalik Hans-Juergen P. Adler Andreas Plagge Martin Stratmann 《Macromolecular Symposia》2002,177(1):97-110
Cellulose as natural and non-toxic material is very interesting for biological applications. Its poor solubility in organic solvents can be improved by introduction of long alkyl chains. Phosphate-substituted cellulose derivatives form ultra-thin layers on several metal surfaces [1, 2]. The layers were applied on the surfaces via dip coating from dilute solutions and characterised by contact angle measurements. Initial corrosion tests were performed. These polymers were applied as adhesion promoters for steel-, titanium- and hydroxy apatite surfaces. Medical implants were pre-treated by UV irradiation, coated with the cellulose derivatives and activated by hot water treatment. The adhesion of the implants surpassed that of conventionally used PMMA systems. 相似文献
4.
For grafting polypyrrole layers on oxidic substrates, the synthesis and characterization of a new adhesion promoter 11‐(pyrrol‐3‐yl) undecyl trimethoxysilane (PyTMS) were described in this article. The oxidation potential of PyTMS was determined by cyclic voltammetry. The grafting behavior of such an adhesion promoter on oxidized surface and chemical deposition of polypyrrole over the modified oxidized surface were studied. The adsorbed layer on the oxidized substrates thus formed was determined by both contact angle measurements and X‐ray photoelectron spectroscopy. Chemical polymerization of terminal pyrrole moieties on such substrates yielded adhesive polypyrrole films, and SEM image showed that the morphology of the polypyrrole films was influenced by the experimental conditions. 相似文献
5.
The macroscopic permeability of random lattices has been studied when the permeability of each link is a power law of its length with an exponent . When they are sufficiently long, the link lengths are shown to follow exponential laws which depend on the density. The macroscopic permeability is studied as a function of ; it is compared to a modified effective medium theory (EMT).*Author for correspondence: e-mail: adler@ipgp.jussieu.fr**e-mail: le_chic@mail.ru 相似文献
6.
The authors consider the steady propagation of a two-dimensionaldiffusioncontrolled smouldering reaction front parallel to theplane boundary of a semi-infinite nonporous reactant. The reactionfront is assumed to be a sheet of line heat sources of variablestrength. The distribution of oxidizer concentration and temperaturein the porous burnt char and of the temperature in the reactantis determined in the form of an asymptotic expansion involvinga similarity variable. The temperature on the reaction frontin the asymptotic region is found to be constant to high order.The dependence of this temperature on the Lewis numbers associatedwith the reactant and the char is found to be in general agreementwith observations. 相似文献
7.
ω-(Pyrrol-1-yl alkyl) dimethylchlorosilanes with different chain length were synthesized and characterized with IR, NMR and elemental analysis. The growth of self-assembled monolayers of ω-(pyrrol-1-yl alkyl) dimethylchlorosilanes on oxide surfaces has been investigated. The order gradually improved with adsorption time and highly ordered SAMs were obtained for nearly 2 days adsorption time. Characterization of the films has been performed with contact angle measurements, ellipsometry, SPR and grazing incident FTIR. The chemical deposition of polypyrrole on the modified surface was investigated. The thickness of polypyrrole layer was influenced by the concentration of monomer, the deposition time, and the ratio of monomer to oxidant. 相似文献
8.
Petar P. Novakov Dirk Kuckling Ljubov Fedorova P. Hans-Juergen Adler 《Macromolecular Symposia》1998,128(1):195-201
Novel branched blockcopolymers from polyvinylpyridine are formed by chromium allyl compounds. Our present work shows results for the homopolymerization of vinylpiridine (VP), dimethylacrylamide (DMAA), tert - butylacrylate (t - BA) as well as the graftcopolymerization of poly(vinylpyridine) (PVP), using tris (π - allyl) chromium (TPC) as initiator. PVP activated by TPC was used for grafting with DMAA - “grafting from”. On the other hand living PDMAA polymerized by TPC, was able to react with PVP chain - “grafting onto”. 相似文献
9.
OUR attention has been drawn to the fact that the criticalitycondition * = 1 of Adler & Herbert (1985), for well-stirredreactive systems, has been derived previously (Gray, 1975).It arises from an examination of trajectories in the temperaturereactant phase plane when a tube stability argument is employed.Using the criterion * = 1, values of the critical Semenov numberhave also been obtained numerically (Gray & Jones, 1981). Our work on criticality for systems with reactant consumptioncame about by trying to reconcile the inflection criterion ofBoddington et al. (1983), for finite B, with the correspondingmaximum criterion in the limit B . Our contribution was to showthat the Semenov number versus maximum temperature * curvehas a bifurcation at * = 1 for all B. Both Gray's work and ourown are attempting to resolve the same problem; the approachesare, however, quite distinct and complement each other 相似文献
10.
Susann Schachschal Andrij Pich Hans-Juergen Adler 《Colloid and polymer science》2007,285(10):1175-1180
In the present paper, we describe the preparation of hybrid particles consisting of polymeric core with deposited hydroxyapatite
(HAp) nanocrystals. Polystyrene submicron particles modified by β-diketone groups have been used as templates for the growth of HAp. Hybrid particles with HAp nanocrystal content between
7 and 50 wt% have been prepared. Microscopy studies indicate that hybrid particles exhibit “raspberry” morphology, and HAp
nanoparticles are not homogeneously distributed on the polymer particle surface. The increase in the HAp content on the polymer
particle surface reduces the colloidal stability of the hybrid particles because of the vanishing of the surface charge. 相似文献