Preparation and Characterization of Polyimide-Silica Nanocomposites by Sol-Gel Process

2006 ◽  
Vol 111 ◽  
pp. 111-114 ◽  
Author(s):  
Yao Yi Cheng ◽  
Kun Chang Chuang
Keyword(s):  
Sol Gel ◽  
Amic Acid ◽  
Silica Content ◽  
Nano Particles ◽  
Hybrid Thin Film ◽  
Silica Nanocomposites ◽  
Sol Gel Process ◽  
Tetracarboxylic Dianhydride

Polyimide (PI)-based nanocomposites were prepared by the in-situ generation of organic silica nano-particles through a sol-gel process, combined with spin coating and multi-step curing process. In this study, silica nano-particles were introduced into the PI matrix to promote its thermal properties. Nanometer-scale composites were successfully obtained from poly(amic acid) (PAA) mixture loaded with silica. 3,3’,4,4’- Biphenyl tetracarboxylic dianhydride (BPDA) and p-phenylenediamine (p-PDA) were employed to synthesize the PAA precursor. The hybrid thin film was prepared from aminoalkoxysilane-capped PAA and tetraethoxysilane (TEOS). In this work, we investigated the effect of coupling agent, 3-aminopropyltriethoxysilane (APrTEOS). The TGA results indicate that the thermal stability of the nanocomposites can be enhanced as silica content increases. Without the incorporation of APrTEOS, less improvement can be achieved.

Polypropylene wax (PPw)/silica hybrid by in situ non-aqueous sol–gel process for preparation of PP/silica nanocomposites

2010 ◽  
Vol 56 (3) ◽  
pp. 300-309 ◽  
Author(s):  
Jun Qian ◽  
Huagui Zhang ◽  
Guangchun Cheng ◽  
Zhijuan Huang ◽  
Shuaiying Dang ◽  
...  
Keyword(s):  
Sol Gel ◽  
Silica Nanocomposites ◽  
Sol Gel Process ◽  
Silica Hybrid

Preparation and characterization of nanocrystalline CoFe2O4 deposited on SiO2: in situ sol–gel process

2010 ◽  
Vol 58 (1) ◽  
pp. 24-32 ◽  
Author(s):  
I. Prakash ◽  
N. Nallamuthu ◽  
P. Muralidharan ◽  
M. Venkateswarlu ◽  
Manjusri Misra ◽  
...  
Keyword(s):  
Sol Gel ◽  
Sol Gel Process

MORPHOLOGY AND CHARACTERIZATION OF POLYIMIDE/POLYSILSESQUIOXANE HYBRID FILMS WITH MESO/MACRO DOUBLE POROUS STRUCTURE

2004 ◽  
Vol 13 (03n04) ◽  
pp. 541-545
Author(s):  
KYUNG-IL KIM ◽  
JUN-YOUNG LEE ◽  
JOON-HYUN AN ◽  
JUNG-HYUN KIM
Keyword(s):  
Porous Structure ◽  
Organic Molecules ◽  
Hybrid Film ◽  
Sol Gel ◽  
Matrix Material ◽  
Hybrid Films ◽  
Hybrid Thin Film ◽  
Sol Gel Process ◽  
Temperature And Pressure

Supercritical CO 2 ( ScCO 2) can dissolve organic materials easily just by changing temperature and pressure. This property of ScCO 2 can be applied to extract some ScCO 2-philic organic molecules from matrix material. The ScCO 2 was used to generate the meso/macro double porous structure of polyimide/polysilsesquioxane (PI/PSSQ) hybrid film. The morphology of the porous structure was measured by scanning electron microscope (SEM). Here, we demonstrate that the ScCO 2 could penetrate into the hybrid thin film and take away the small molecules, which are the by-product ( CO 2) from the imidization reaction of the PI segment and the solvent remained in the PSSQ segment by sol-gel process.

Characterization of lanthanum salicylate complex nanoparticles in situ synthesized in silica matrix by a sol–gel process

2004 ◽  
Vol 58 (5) ◽  
pp. 757-761 ◽  
Author(s):  
Xiaofei Yang ◽  
Qizhuang He ◽  
Xianghong He ◽  
Liang Huang
Keyword(s):  
Sol Gel ◽  
Silica Matrix ◽  
Sol Gel Process

scholarly journals Photocatalytic Degradation of Herbicide Orthosulfamuron using Zinc Oxide Nanoparticles in Water

2020 ◽  
Author(s):  
Gaggara Naveetha ◽  
Atmakuru Ramesh ◽  
Chirukuri Rajasekharam
Keyword(s):  
Degradation Products ◽  
Sol Gel ◽  
Amic Acid ◽  
Optimum Concentration ◽  
Nano Particles ◽  
Buffer Solution ◽  
Initial Concentration ◽  
Sol Gel Process ◽  
Rate Of Reaction ◽  
Ft Ir

In the present study, the Photocatalysis of Orthosulfamuron, a new class of sulfonyl urea herbicide was investigated using ZnO nano particles in different buffer solutions of pH ranging from 4 to 9. In this study, optimum concentration of the catalyst, initial concentration of the orthosulfamuron and effect of pH of the buffer solution were studied under direct sunlight. The ZnO nano particles were synthesized by sol-gel process and characterized by using SEM, XRD and FT-IR. A commercial formulation of the herbicide having the active strength of 50% was used for the experiment. The rate of reaction followed pseudo first-order kinetics in water. The rate of reaction was 12 folds higher when compared to photolysis. The DT50 values of orthosulfamuron with ZnO nano particles in different buffer solution were 6. 42, 21.68 and 35.22 hours, respectively. The optimum concentration of nano particles to decontamination of orthosulfamuron was observed at 100 mg L-1 and the initial concentration of the orthosulfamuron used in the photocatalysis is 10 mg L-1. The fastest degradation of herbicide orthosulafamuron was observed in pH 4 buffer solution. The degradation products formed during the photocatalysis were identified by using LC-MS/MS which were N-(4,6-dimethoxypyrimidin-2-yl) urea, 2- dimet hyl carbamoyl phenyl sulf amic acid and 1-(4-hydroxy-6-methoxypyrimidin-2-yl)-3-[2-(dimethylcarbamoyl) pheny lsulfamoyl] urea.

scholarly journals Microstructure and Thermomechanical Properties of Polyimide-Silica Nanocomposites

2006 ◽  
Vol 2006 ◽  
pp. 1-9 ◽  
Author(s):  
A. Al Arbash ◽  
Z. Ahmad ◽  
F. Al-Sagheer ◽  
A. A. M. Ali
Keyword(s):  
Sol Gel ◽  
Thermomechanical Properties ◽  
Silica Content ◽  
Hydroxyl Groups ◽  
Thermal Coefficient ◽  
Silica Network ◽  
Interphase Interaction ◽  
Silica Nanocomposites ◽  
Sol Gel Process ◽  
Alkoxy Groups

Novel polyimide-silica nanocomposites with interphase chemical bonding have been prepared using the sol-gel process. The morphology, thermal and mechanical properties were studied as a function of silica content and compared with the similar composites having no interphase interaction. The polyimide precursors, polyamic acids (PAAs) with or without pendant hydroxyl groups were prepared from the reaction of pyromellitic dianhydride with a mixture of oxydianiline and 1,3 phenylenediamine or 2,4-diminophenol in dimethylacetamide. The PAA with pendant hydroxyl groups was reacted with isocyanatopropyltriethoxysilane to produce alkoxy groups on the chain. The reinforcement of PAA matrices with or without alkoxy groups on the chain was carried out by mixing appropriate amount of tetraethoxysilane (TEOS) and carrying out its hydrolysis and condensation in a sol-gel process. Thin hybrid films were imidized by successive heating up to 300C∘. The presence of alkoxy groups on the polymer chain and their cocondensation with TEOS developed the silica network which was interconnected chemically with the polyimide matrix. SEM studies show a drastic decrease in the silica particle size in the chemically bonded system. Higher thermal stability and mechanical strength, improved transparency, and low values of thermal coefficient of expansion were observed in case of chemically bonded composites.

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