Structure Determination of Aromatic Polyesters Liquid Crystal Polymers

Characteristics of LCPs § Flame retardant (140 °C) § Chemical resistance (oxygen) § Excellent

Current Uses of LCPs § Electronic (electronic, optoelectronic, fiberoptics) § Fillers (glass fibers, carbon

LCPs in Space? § § § Stable (not oxidized) Much lighter than metal Fuel

Questions § What are the structures of the polymers? – Internal groups - End

Methods § Extraction of small molecules, MS - Hexafluoroisopropanol (HFIP) § Depolymerization, NMR -

Nuclear Magnetic Resonance http: //www 2. potsdam. edu/walkerma/341 nmr 1 b. GIF

§ Na. OD/D 2 O Results - 5 to 7% more acids than phenols

Discussion § The presence of anhydrides was indicated by NMR methods § MS/MS also

Conclusions § A quantitative procedure for converting LCPs back to monomers was developed §

More Conclusions § Anhydrides can be avoided by starting with excess phenols § Identifying

Acknowledgements § § § NASA Solvay Dr. Hall and Dr. Bates

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Structure Determination of Aromatic Polyesters (Liquid Crystal Polymers) Cristina Contreras

Characteristics of LCPs § Flame retardant (140 °C) § Chemical resistance (oxygen) § Excellent flow in mold (~ 320 °C) § Mesomorphism (neither liquid nor crystal) § Transparent to microwave radiation

Current Uses of LCPs § Electronic (electronic, optoelectronic, fiberoptics) § Fillers (glass fibers, carbon fibers, mineral fillers) § Electronic packaging

LCPs in Space? § § § Stable (not oxidized) Much lighter than metal Fuel tanks for liquid oxygen

Polymerization

Monomers

Questions § What are the structures of the polymers? – Internal groups - End groups

Methods § Extraction of small molecules, MS - Hexafluoroisopropanol (HFIP) § Depolymerization, NMR - Na. OD/D 2 O - Isopropylamine

Mass Spectrometry

Nuclear Magnetic Resonance http: //www 2. potsdam. edu/walkerma/341 nmr 1 b. GIF

Depolymerization with Amines

§ Na. OD/D 2 O Results - 5 to 7% more acids than phenols § Isopropylamine - 5% of products indicating anhydrides

Discussion § The presence of anhydrides was indicated by NMR methods § MS/MS also supported anhydrides but was not quantitative

Conclusions § A quantitative procedure for converting LCPs back to monomers was developed § A mass spectral method for observing the smaller polymer molecules was found § Anhydrides units were observed in the polymer, making them less stable to water

More Conclusions § Anhydrides can be avoided by starting with excess phenols § Identifying small molecules for environmental concerns

Acknowledgements § § § NASA Solvay Dr. Hall and Dr. Bates