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Analytical Method for In-Situ Molecular Weight Determination of Perfluorinated Ethers

IP.com Disclosure Number: IPCOM000047434D
Original Publication Date: 1983-Nov-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Gutierrez, A: AUTHOR [+2]

Abstract

Perfluorinated ethers are used in many industrial processes. As a result of this a number of special analytical techniques have been devised to measure various physical and chemical properties for the materials under unique circumstances. Here, we describe a method that is capable of determining the molecular weight for a perfluorinated ether when it is present in very small quantities, e.g., as a thin film on a substrate. The method is demonstrated for a particular class of perfluorinated ethers; their structure is shown below: CF3CF2(CF(CF3)CF20)n(CF20)mCF2CF3 n>>m molecular weight N/N 8,000 Samples, whose molecular weights were known, were spin coated onto gold-plated copper substrates to achieve a thickness of about one micron.

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Analytical Method for In-Situ Molecular Weight Determination of Perfluorinated Ethers

Perfluorinated ethers are used in many industrial processes.

As a result of this a number of special analytical techniques have been devised to measure various physical and chemical properties for the materials under unique circumstances. Here, we describe a method that is capable of determining the molecular weight for a perfluorinated ether when it is present in very small quantities, e.g., as a thin film on a substrate. The method is demonstrated for a particular class of perfluorinated ethers; their structure is shown below: CF3CF2(CF(CF3)CF20)n(CF20)mCF2CF3 n>>m molecular weight N/N 8,000 Samples, whose molecular weights were known, were spin coated onto gold-plated copper substrates to achieve a thickness of about one micron. The samples were subsequently enclosed in a vacuum system and irradiated with a 25 kv electron beam. The current in the electron beam was accurately determined using a Faraday cup in order to obtain the incident dose to which the sample was exposed. The infrared spectrum of the sample was recorded before and after each exposure so that the decay in number density of the CF bonds could be found as a function of incident electron beam dose. When the log of the normalized decrease of the CF bonds is plotted against the incident dose, the slope s is the cross section for the chemical damage. The cross sections were obtained for a number of samples with di...