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1.
Ahmed Jalal Uddin Yutaka Ohkoshi Yasuo Gotoh Masanobu Nagura Tetsuya Hara 《Journal of Polymer Science.Polymer Physics》2003,41(22):2878-2891
The effect of moisture on the mechanical relaxation processes of semiaromatic semicrystalline polyamides synthesized by a long‐chain aliphatic diamine and terephthalic acid was investigated by dynamic viscoelastic analysis (DVA) and differential scanning calorimetry (DSC). Moreover, the implication of moisture with the amorphous and crystalline domains was also examined by temperature‐dependent wide‐angle X‐ray diffraction and Fourier transform infrared spectra. The characteristics of the relaxations such as α, β, γ, and the pronounced peak shoulder appeared at 25–100 °C in DVA tan δ curves were found to be strongly susceptible to the presence of moisture. With moisture evaporation, the peak shoulder of 25–100 °C and the β‐relaxation disappeared. The former is anticipated to originate from to the side group motion of hydrogen‐bonded water, whereas the later one is from the motions of the amide–water complex units. With the disappearance of the β‐relaxation, the γ‐relaxation appeared simultaneously in much lower temperatures and ultimately coupled with the δ‐relaxation. The γ‐relaxation is attributed to be associated with the molecular motion of the amide group and δ‐relaxation with for the motion of the methylene units. The existence of two types of water was identified in the polymer, namely, tightly bound and loosely bound. The tightly bound water is believed to be directly connected by hydrogen bonding with the strong polar groups and the loosely bound water weakly links with those connected water making hydrogen bridges. The moisture acts as a plasticizer in the polymer matrix, which causes quite a large depression in its glass transition temperature (Tg). WAXD and FTIR studies corroborated the existence of water solely in amorphous regions, i.e., no rapport of water with the crystalline parts. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 2878–2891, 2003 相似文献
2.
Yasuhiro Gotoh 《Journal d'Analyse Mathématique》1998,75(1):67-84
Extending results of Staples and Smith-Stegenga, we characterize measurable subsets of a given domainD ⊃R
n on which BMO(D) functions areL
p
integrable or exponentially integrable. In particular, we characterize uniform domains by the integrability of BMO functions.
We also remark on the boundedness of domains satisfying a certain integrability condition for the quasihyperbolic metric. 相似文献
3.
Summary The potential ranges of polarization of a pair of dropping mercury electrodes, over which the two mercury droplets coalesced, were measured as functions of ionic concentrations for various electrolytes. In the case of simple inorganic electrolytes the condition of coalescence obtained was proved to be in quantitative agreement with theVerwey-Overbeek theory of coagulation of lyophobic sols, thus indicating that the interaction between sub-microscopic particles of hydrophobic sols is essentially the same as that between macroscopic mercury droplets. While, in the case of sodium citrate solutions two kinds of marked deviations from the theory were observed, which appeared to be due to the specific adsorption of citrate ions and to the formation of protective interfacial films.
Zusammenfassung Die Potentialbereiche der Polariation eines Paares von Quecksilber-Tropfelektroden, über die die beiden Quecksilbertropfen koaleszieren, werden als Funktion der Ionenkonzentration verschiedener Elektrolyte gemessen. Im Fall einfacher anorganischer Elektrolyte wurde die erhaltene Bedingung der Koaleszenz mit der Theorie vonVerwey-Overbeek der Kaogulation lyophober Sole geprüft und in quantitativer übereinstimmung befunden. Das zeigt, da\ die Wechselwirkung zwischen submikroskopischen Partikeln hydrophober Sole im wesentlichen dieselbe ist wie zwischen den makroskopischen Quecksilbertröpfchen. Dagegen ergaben sich im Fall von Natriumzitratlösungen zwei Arten markanter Abweichungen von der Theorie. Diese scheinen spezifische Adsorption der Zitrationen und die Ausbildung von SchutzgrenzflÄchenfilmen zur Ursache zu haben.相似文献
4.
Noriaki Nagai Mayu Kawaguchi Misa Minami Kana Matsumoto Tatsuji Sasabe Kenji Nobuhara Akira Matsubara 《Molecules (Basel, Switzerland)》2022,27(10)
N,N-diethyl-3-toluamide (DEET) is one of the most widely used insect repellents in the world. It was reported that a solution containing 6–30% cyclodextrin (CD) as a solvent instead of ethanol (EtOH) provided an enhancement of the repellent action time duration of the DEET formulation, although the high-dose CD caused stickiness. In order to overcome this shortcoming, we attempted to prepare a 10% DEET formulation using EtOH containing low-dose CDs (β-CD, 2-hydroxypropyl-β-CD (HPβCD), methyl-β-CD, and sulfobutylether-β-CD) as solvents (DEET/EtOH/CD formulations). We determined the CD concentration to be 0.1% in the DEET/EtOH/CD formulations, since the stickiness of 0.1% CDs was not felt (approximately 8 × 10−3 N). The DEET residue on the skin superficial layers was prolonged, and the drug penetration into the skin tissue was decreased by the addition of 0.1% CD. In particular, the retention time and attenuated penetration of DEET on the rat skin treated with the DEET/EtOH/HPβCD formulation was significantly higher in comparison with that of the DEET/EtOH formulation without CD. Moreover, the repellent effect of DEET was more sustained by the addition of 0.1% HPβCD in the study using Aedes albopictus. In conclusion, we found that the DEET/EtOH/HPβCD formulations reduced the skin penetration of DEET and prolonged the repellent action without stickiness. 相似文献
5.
Jun Oshitani Shiho Takashina Mikio Yoshida Kuniaki Gotoh 《Colloids and surfaces. A, Physicochemical and engineering aspects》2009,350(1-3):136-140
The objective of this study is to estimate the contribution of Na+ as a counterion in the formation of H-AOT&Na-AOT-based W/O microemulsions using aqueous NaOH solution by pyranine absorbance measurements. A mixture of an aqueous NaOH solution containing pyranine/H-AOT&Na-AOT/isooctane was emulsified by changing the mixing ratio of Na-AOT (XNa-AOT = 0–1) and the mole fraction of NaOH (XNaOH = [NaOH]/the AOT− concentration in the water pool = 0–1). The phase behavior of the emulsified mixture was evaluated from the absorbance of pyranine at the isosbestic point and by visual observations. W/O microelumsions are formed at the mid-range of XNa-AOT, whereas the emulsified mixture separates into two phases at lower XNa-AOT and higher XNa-AOT. The two phase boundaries shift toward lower XNa-AOT as with increasing XNaOH. The phase behavior depends on the degree of screening of electrostatic repulsions between the polar headgroups of AOT− by the Na+ counterion. Interestingly, nano-sized W/O microemulsions are formed without phase separation using a highly concentrated NaOH aqueous solution when the Na-AOT mixing ratio is appropriately adjusted. The phase behavior was plotted as XNaOH versus XNa-AOT, and the correlation equations for the two phase boundaries were obtained by fitting the points. The contribution of the Na+ counterion from NaOH to W/O microemulsion formation was estimated by the correlation equations. The absorbance of pyranine and the size of W/O microemulsions, as measured by DLS, were plotted as a function of XNa+=(x[Na+ from NaOH]+[Na+ from Na-AOT])/[AOT−], in which x is the ratio contributed by NaOH. The absorbance and size correlates well with XNa+, indicating that XNa+ is a meaningful parameter for quantitatively estimating phase behavior and size variation. 相似文献
6.
Though phase selective organogelators (PSOGs) are thought to be useful for oil spill recovery, all known PSOGs require a water-miscible carrier solvent for their introduction. Providing a simple, cheap, green and practical solution to the problem of oil spills, we report a nontoxic super-PSOG that can be sprayed aerially in a carrier solvent destined to get co-congealed with the oil. 相似文献
7.
An efficient method for the synthesis of 2,5-dihydroisoxazoles and isoxazoles using iodocyclization of N-alkoxycarbonyl O-propargylic hydroxylamines has been developed. 2,5-Dihydro-4-iodoisoxazole underwent the cross-coupling reactions without aromatization to afford polyfunctionalized 2,5-dihydroisoxazoles. This process was applied to the preparation of valdecoxib and its 2,5-dihydro-derivative. 相似文献
8.
Synthesis and Reversible Hydration of a Pseudoprotein,a Fully Organic Polymeric Desiccant by Multiple Single‐Crystal‐to‐Single‐Crystal Transformations 下载免费PDF全文
Raja Mohanrao Prof. Dr. Kana M. Sureshan 《Angewandte Chemie (International ed. in English)》2018,57(38):12435-12439
A diphenylalanine derivative, N3‐Phe‐Phe‐NHCH2CCH, was designed for topochemical azide–alkyne cycloaddition (TAAC) polymerization. This dipeptide adopted β‐sheet arrangement as designed, in its crystals, but the azide and alkyne were not fitly aligned for their topochemical reaction. However, the voids present around these groups allowed them to attain a reactive geometry upon heating and their consequent TAAC polymerization to a pseudoprotein in a single‐crystal‐to‐single‐crystal (SCSC) fashion. This motion led to the creation of channels in the product crystal and it absorbed water from the surroundings to fill these channels as H‐bonded water wire. The pseudoprotein undergo reversible hydration/dehydration in SCSC fashion many times under mild conditions: hydration at low relative humidity and dehydration at low temperature. Vapor sorption analyses suggest that this fully organic polymer might be useful as an energy‐efficient desiccant material for controlling indoor humidity. 相似文献
9.
Tanaka K Kukita K Ichibakase T Kotani S Nakajima M 《Chemical communications (Cambridge, England)》2011,47(19):5614-5616
Chiral lithium binaphtholate effectively catalyzed the enantioselective alkynylation of ketones using lithium acetylide as an alkynylating agent. This is the first example of the catalytic enantioselective addition of lithium acetylide to carbonyl compounds without the aid of other metal sources. 相似文献
10.
Hiroyuki Nishide Naoki Yoshioka Yukoh Saitoh Ritsuko Gotoh Takeshi Miyakawa Eishun Tsuchida 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(9):775-786
Abstract m- and p Bis(diphenylene)propenylphenylacetylene (m-, p-8) were synthesized and polymerized with WCI6, MoCl5, and Rh catalyst, yielding solvent-soluble poly(phenylacetylene)s bearing a π-conjugated bis(di-phenylene)propenyl groups (m-, p-7a). The polymers gave their polyanion derivatives, which were electrolytically and chemically oxidized to yield the corresponding polyradicals (m-, p-7b). The polyradicals were chemically very stable due to the resonance stabilization of an unpaired electron whose spin concentration could be increased up to ca. 2 × 1023 spins per molar monomer unit. ESR spectroscopy suggested an antiferro-magnetic interaction between unpaired electrons. 相似文献