Control Over Al2O3 Phase by Use Of Polymer Precursors

1991 ◽  
Vol 249 ◽  
Author(s):  
William S. Rees ◽  
Werner Hesse
Keyword(s):  
Solid State ◽  
Ethylene Glycol ◽  
Ceramic Materials ◽  
Crystal Phase ◽  
Cross Linking ◽  
Dry Air ◽  
Polymer Precursors ◽  
Initial Polymer ◽  
Al2o3 Phase ◽  
Flowing Atmosphere

ABSTRACTReaction of Et2AIOEt with ethylene glycol or catechol produced polymers of the general form -[-AI(OEt)-O-R-O-]-n, for R = CH2CH2 or C6H4, respectively. Pyrolytic conversion of these polymers to ceramic materials produced A12O3, at mild (∼500°C) temperatures under a flowing atmosphere of dry air. The crystal phase obtained from the thermolysis is highly dependent upon the degree of cross-linking present in the initial polymer. These results are discussed in terms of the required solid-state atomic reorganization necessary to proceed from polymer to ceramic.

Development and Characterization of LBG-PVA Interpenetrating Networks Incorporating Gliclazide for Sustained Release

2020 ◽  
Vol 15 ◽  
Author(s):  
Ashish Katoch ◽  
Manju Nagpal ◽  
Malkiet Kaur ◽  
Manjinder Singh ◽  
Geeta Aggarwal ◽  
...  
Keyword(s):  
Solid State ◽  
Sustained Release ◽  
Half Life ◽  
Solid State Nmr ◽  
Oral Dosage ◽  
Cross Linking ◽  
Interpenetrating Networks ◽  
Dsc Studies ◽  
Biological Half Life ◽  
Percentage Yield

Background: Controlled oral dosage forms have always been preferred for drugs with variable absorption, and short biological half life and frequent dosing. The prime goal with sustained release systems is to maintain uniform therapeutic blood levels for longer periods of time. Interpenetrating networks (IPNs) have been evidenced as uniform sustained release systems. In current study, polyvinyl alcohol (PVA) and locust bean gum (LBG) based IPNs were developed for the oral sustained release drug delivery of gliclazide (shows variable absorption). Method: The IPNs were synthesized by emulsion cross-linking method using glutaraldehyde (GA) as a cross linking agent. Gliclazide is a potential second generation, short-acting sulfonylurea oral hypoglycemic agent is having a short biological half-life (2-4 h), variable absorption and poor oral bioavailability. Various batches of IPNs were formulated by varying LBG: PVA ratio and evaluated for percentage yield, drug entrapment efficiency (DEE), swelling properties and in vitro drug release studies. Further characterizations were done by Fourier Transform Infrared Spectroscopy (FTIR), C13 Solid state NMR, X-Ray diffraction study (XRD), Scanning electron microscopy (SEM), and Differential scanning microscopy (DSC) studies. Results: The percentage yield, drug entrapment and equilibrium swelling was observed to be dependent on PVA-LBG ratio and GA amount. Sustained release of drug was observed in all IPN formulations (approx 59 - 86% in 8 h in various batches) with variable release kinetics. SEM studies revealed the regular structures of IPNs. FTIR, XRD, C13 Solid state NMR and DSC studies proposed that drug was successfully incorporated into the formed IPNs. Conclusion: IPNs of LBG and PVA can be used as a promising carrier with uniform sustained release characteristics.

Smart control of cotton fabric comfort by cross-linking thermo-responsive poly(2-(2-methoxyethoxy) ethoxyethyl methacrylate-co-ethylene glycol methacrylate)

2016 ◽  
Vol 87 (13) ◽  
pp. 1620-1630 ◽  
Author(s):  
Yangyi Chen ◽  
Jie An ◽  
Qi Zhong ◽  
Peter Müller-Buschbaum ◽  
Jiping Wang
Keyword(s):  
Ethylene Glycol ◽  
Cotton Fabric ◽  
Random Copolymer ◽  
Cotton Fabrics ◽  
Molar Ratio ◽  
Cross Linking ◽  
Glycol Methacrylate ◽  
Moisture Permeability ◽  
Smart Control ◽  
Fabric Comfort

The smart control of cotton fabric comfort by cross-linking thermo-responsive random copolymer is investigated. The monomers 2-(2-methoxyethoxy) ethoxyethyl methacrylate (MEO2MA) and ethylene glycol methacrylate (EGMA) with a molar ratio of 17:3 are selected to synthesize the thermo-responsive random copolymer poly(2-(2-methoxyethoxy) ethoxyethyl methacrylate- co-ethylene glycol methacrylate), abbreviated as P(MEO2MA- co-EGMA). By using citric acid as a cross-linking agent, the obtained P(MEO2MA- co-EGMA) is successfully immobilized onto cotton fabrics. Smart control is achieved from the thermo-responsive behavior of the copolymer. Cross-linked P(MEO2MA- co-EGMA) will collapse when the ambient temperature exceeds its transition temperature. Therefore, the formerly compact P(MEO2MA- co-EGMA) layer will switch to a porous structure, and the air/moisture permeability of the textiles is enhanced. As the comfort of the textiles is closely related to the air/moisture permeability, a smart control of the cotton fabric comfort can be realized. In addition, the softness of cotton fabrics with and without thermo-responsive polymers does not show a prominent change, even when the applied solution concentration is as high as 16% (wt%). On the contrary, the stiffness of the cotton fabric coated with poly( N-isopropylacrylamide) (PNIPAM) is significantly higher than the original cotton fabric, indicating that homo PNIPAM is less suitable for textiles used in daily lives. Moreover, the whiteness and mechanical properties are studied and stay unchanged after cross-linking. As a consequence, the introduction of P(MEO2MA- co-EGMA) into textiles can provide textiles with smart control of cotton comfort, and it will not influence the wearabilities of the textiles.

Chemically Designed, UV Curable Polycarbosilane Polymers

1992 ◽  
Vol 271 ◽  
Author(s):  
Kevin J. Thorne ◽  
Stephen E. Johnson ◽  
Haixing Zheng ◽  
John D. Mackenzie ◽  
M. F Hawthorne
Keyword(s):  
Molecular Weight ◽  
Inert Atmosphere ◽  
Uv Exposure ◽  
Cross Linking ◽  
Substitution Reactions ◽  
High Solubility ◽  
Chemical Route ◽  
Uv Curable ◽  
Polymer Precursors ◽  
C Nmr

ABSTRACTTo prepare new polycarbosilane polymer precursors with high solubility and the capability of UV cross-linking, commercial polycarbosilane was modified by a chemical route. These modifications involved AlCl3 catalyzed chlorination reactions of polycarbosilane's Si-H bonds. The resultant Si-Cl bonds were substituted by a reaction with sodium acetylyde to form Si-C=CH ligands. These ligands are suitable for controlled, free radical initiated cross-linking of the polycarbosilane polymers. The increase in molecular weight should allow for increased Tg's and the retention of polymer pre-forms. In this report, the chlorination of the polycarbosilane polymer and the substitution reactions of polycarbosilane were examined with IR, 29Si and 13C NMR spectroscopy. In addition, the retention of polymer pre-forms were analyzed after UV exposure and inert atmosphere pyrolysis.

A chitosan/poly(ethylene glycol)-ran-poly(propylene glycol) blend as an eco-benign separator and binder for quasi-solid-state supercapacitor applications

2019 ◽  
Vol 3 (3) ◽  
pp. 760-773 ◽  
Author(s):  
M. Raja ◽  
Balaji Sadhasivam ◽  
Janraj Naik R ◽  
Dhamodharan R ◽  
Kothandaraman Ramanujam
Keyword(s):  
Activated Carbon ◽  
Solid State ◽  
Ethylene Glycol ◽  
Propylene Glycol ◽  
Tamarindus Indica ◽  
Poly Ethylene Glycol ◽  
Active Electrode ◽  
Poly Ethylene ◽  
Poly Propylene ◽  
Supercapacitor Applications

In this study chitosan/poly(ethylene glycol)-ran-poly(propylene glycol) blend was developed as separator and binder for supercapacitor (SC) applications. The activated carbon (ACTS-900) derived fromTamarindus indicaseeds is used as active electrode material.

scholarly journals Thermoelectric Study of La2Ti2-xNbxO7 (0≤x≤0.25) Ceramic Materials

2020 ◽  
pp. 38-47
Author(s):  
A. C. Iyasara ◽  
F. U. Idu ◽  
E. O. Nwabineli ◽  
T. C. Azubuike ◽  
C. V. Arinze
Keyword(s):  
Crystal Structure ◽  
Thermal Conductivity ◽  
Solid State ◽  
Single Phase ◽  
Ceramic Materials ◽  
Solid State Reaction Method ◽  
Reaction Method ◽  
Reducing Atmosphere ◽  
High Seebeck Coefficient ◽  
Porous Microstructures

La2Ti2-xNbxO7 (x = 0.00, 0.05, 0.10, 0.15, 0.20, 0.25) powders were synthesised via solid state reaction method, followed by sintering at 1673 K in a reducing atmosphere of 5% H2/N2 gas. The crystal structure, microstructure and thermoelectric (TE) properties of the pure and Nb-doped La2Ti2O7 ceramics were investigated. All compositions were single phase with porous microstructures consistent with their low experimental densities. Thermoelectric results of Nb-doped compositions showed improved properties in comparison to pure La2Ti2O7, suggesting that cation doping has the potential to improve the thermoelectric properties. Generally, the TE results obtained are not suitable for thermoelectric applications. However, the high Seebeck coefficient (≥190 μV/K) and glass-like thermal conductivity ( ≤2.26 w / m.k )  values achieved have opened a new window for exploring the thermoelectric potentials of La2Ti2O7 and other related oxides.

Ethylene glycol assisted self-template conversion approach to hollow NiS microspheres for high performance all-solid-state supercapacitor

2021 ◽  
Author(s):  
Maiyong Zhu ◽  
Xuan Li ◽  
Chengyu Tu ◽  
Qiao Luo ◽  
Yijing Nie ◽  
...  
Keyword(s):  
Solid State ◽  
Ethylene Glycol ◽  
High Performance ◽  
Soft Template ◽  
Hollow Structures

Traditional hard/soft template approaches to hollow structures suffer from tedious procedures and time-consuming. Compare to these methods, self-template approaches usually gain advantages of step-economy. Herein, solid spherical Ni-glycolate/Ni microspheres were...

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