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81.
Hydrolytic degradation of POSS-PEG-lactide hybrid hydrogels 总被引:2,自引:0,他引:2
A polyhedral oligomeric silsesquioxane (POSS), functionalized with eight arms of poly(ethylene glycol) (PEG; MW 400) and then acrylated, was incorporated into a hydrogel network based on triblock copolymers of poly(lactide-b-ethylene glycol-b-lactide) diacrylates using a redox-initiated polymerization. The organic-inorganic hybrid hydrogels so prepared contained the inorganic crosslinker POSS from 1 to 28 wt.%. The degradation properties of the hydrogels in a pH 7.4 phosphate-buffered saline solution at 37 °C were studied using measurements of mass loss, cryogenic SEM, and ATR-FTIR spectroscopy. It was found that copolymerization of acrylated 1kPEG-lactide with increasing amounts of POSS created a more porous network which was more resistant to hydrolysis. The ATR-FTIR technique was used to monitor the progress of degradation with exposure time through the changes in the carbonyl and C-H deformation bands of the lactide and the Si-C stretching band of the POSS. Increasing POSS incorporation resulted in decreased rate of degradation due to its hydrophobic nature and inertness to hydrolysis. Conversely, an increase in lactide content increased the degradation rate due to the increased number of hydrolytically-sensitive ester groups in the network. 相似文献
82.
Poly(ethylene glycol) (PEG) hydrogels have been used to encapsulate fluorescently labeled molecules in order to detect a variety
of analytes. The hydrogels are designed with a mesh size that will retain the sensing elements while allowing for efficient
diffusion of small analytes. Some sensing assays, however, require a conformational change or binding of large macromolecules,
which may be sterically prohibited in a dense polymer matrix. A process of hydrogel microporation has been developed to create
cavities within PEG microspheres to contain the assay components in solution. This arrangement provides improved motility
for large sensing elements, while limiting leaching and increasing sensor lifetime. Three hydrogel compositions, 100% PEG,
50% PEG, and microporated 100% PEG, were used to create pH-sensitive microspheres that were tested for response time and stability.
In order to assess motility, a second, more complex sensor, namely a FITC-dextran/TRITC-Con A glucose-specific assay was encapsulated
within the microspheres. 相似文献
83.
《Analytical letters》2012,45(7):1279-1289
Abstract Based on the fact that nonionic surfactant polyethylene glycol-400 (PEG-400) catalyzed the chemiluminescence of luminol-H2O2 system, a novel and simple chemiluminescence method has been developed for the determination of PEG-400. Under the optimal conditions, the standard curve was Y = 198835X–2091.8, where the correlation coefficient (R) was 0.9999. The detection limit was 4 × 10?5 g·ml?1 PEG-400 and the linear range was 1.0 × 10?4–4.0 × 10?2g·ml?1. The relative standard deviation was 3.2% at 2.0 × 10?3 g·ml?1 PEG-400 (n = 7). This method has been applied to the determination of PEG-400 in cosmetic samples with satisfactory results. Furthermore, the dynamics characteristic curve of PEG-400 in luminol-H2O2 system was compared to typical metallic ion and other surfactants. Moreover, the mechanism of the luminol-H2O2-PEG-400 chemiluminescence system was studied, assisted by fluorescence spectra and UV spectra. 相似文献
84.
In recent years the use of monolithic polymers in separation science has greatly increased due to the advantages these materials present over particle-based stationary phases, such as their relative ease of preparation and good permeability. For these reasons, these materials present high potential as stationary phases for the separation and purification of large molecules such as proteins, peptides, nucleic acids and cells. An example of this is the wide range of commercial available polymer-based monolithic columns now present in the market. 相似文献
85.
《Physics and Chemistry of Liquids》2012,50(1):25-34
Abstract The interfacial tension of Polyethylene glycol (PEG)/potassium phosphate two-phase systems was measured by the rotating drop method. The interfacial tension was as low as 0.001 dyne/cm and increased with increases in the total concentrations of both PEG and potassium phosphate in two-phase systems. The increase in the interfacial tension was a function of the concentration differences of PEG and potassium phosphate between the top and the bottom phases which was confirmed by the tie line analysis. The interfacial tension was affected also by the molecular weigth of PEG. At low PEG molecular weights, the increase in the molecular weight greatly increased the interfacial tension, but at high molecular weights, the interfacial tension varied less with the molecular weight. 相似文献
86.
《Physics and Chemistry of Liquids》2012,50(2):181-191
Abstract Salt in polyethylene glycol (PEG)/salt aqueous two-phase systems was excluded by PEG and concentrated in the solvent volume available for dissolution of salt (PEG-free solvent). The concentration of salt in the PEG-free solvent of the PEG-rich phase was the same as that at the critical point regardless of the compositions of the PEG/salt two-phase systems. This explained that the phase separation of PEG/salt two-phase systems occurs when the concentration of salt in the PEG-free solvent reaches its solubility limit. The concentration of salt required in the PEG-free solvent for the phase separation was lower with higher molecular weight of PEG. The solubility of salt in the PEG-free solvent decreased with increases in the molal surface tension increment of salt. The solubility limit of salt in the PEG-free solvent was 0.93 M for ammonium sulfate, 0.77 M for potassium phosphate, 0.75 M for sodium tartrate, 0.67 M for sodium phosphate, and 0.53 M for potassium citrate. 相似文献
87.
以硝酸铝[Al(NO3)39H2O]和硝酸钇[Y(NO3)36H2O]为原料,碳酸氢铵[NH4HCO3]为沉淀剂,PEG400,PEG800和PEG1000等为分散剂,采用正向共沉淀法合成了钇铝石榴石(YAG)前驱体粉末。并用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、粒度测试仪等分析了粉末的形貌和性能。结果表明,分散剂的加入,减少了粉末的团聚现象,而且由PEG400,PEG800分散剂制备的先驱体粉末经1200 ℃煅烧60 min后均能形成纯度较高的YAG相,但PEG1000样品粒度更细,比表面积为1748.78 m2/kg,中位径为1.42 m,而前者所得粉末的比表面积分别为29.39和128.60 m2/kg,中位径分别为196.14和20.55 m。 相似文献
88.
Polyethylene glycol (PEG) was selected as a phase‐change material (PCM) and the phase‐change fibers of its copolymers with polyethylene terephalate (PET), PET‐PEG, were successfully prepared by melt spinning. The PET‐PEG copolymers have solid‐solid phase change characteristics at 10–60°C without obvious liquid substance appearing, while PET/PEG blends will lose their phase‐change characteristics since the PEG of the blends may melt and leak under high temperature. By controlling the molecular weight and relavent proportion of PEG added, the phase‐change temperature range and the enthalpy can be adjusted. 相似文献
89.
90.
The cationization of poly(ethylene glycol)s, PEG 4000 and PEG 6000, under matrix-assisted laser desorption/ionization conditions was studied by using different concentration ratios of the sodium ion, as the reference ion, and another alkali metal ion (Li(+), K(+), Rb(+), Cs(+)). A linear correlation was found between the intensity ratio of the sodiated PEGs and PEGs cationized with alkali metal ions versus the initial concentration ratio of sodium and alkali metal ions. The slopes of these straight lines are proposed as a novel selectivity ratio for the ionization process. The intensity distribution of the cationized PEGs was also investigated. It was found that the cationized oligomers follow Poisson statistics. The M(n) and M(w) values were also evaluated. An explanation for the observed effects is given. 相似文献