The synthesis and characterization of new, fluoride-containing polyacrylates derived from 2-hydroxyhexafluoroisopropylbenzene
Date
1999-05
Authors
Oba, Jean Baptiste
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Abstract
Acrylate polymers are known for their clarity, lack of color and stability upon aging under severe conditions. These characteristics, along with the versatility and ability to tailor these polymers relatively easily to specific applications, have made them good candidates for numerous and diverse applications. Fluorinated polyacrylates are finding increased applications in a wide variety of functions including low dielectric coatings and water repellent prosthetic devices. These polymers have also been shown to be useful for dental, biomedical and optical applications.
The fluorinated alcohol, 4-fluoro-(2-hydroxyhexafluoroisopropyl) benzene (HFAB), had previously been studied and has been shown to be a highly useful starting material for the preparation of new monomers. Incorporation of the hexafluoroisopropylidene (HFIP) moiety into a polymer generally improves a number of properties including solubility, flame resistance, glass transition temperature, thermal stability and oxidative resistance.
The goal of this project was to synthesize new acrylate monomers and polymers in which the HFAB moiety was separated from the polymerizable vinyl group by a hydrocarbon spacer arm in order to facilitate the production of high molecular weight materials. This investigation was divided into three parts:
(1) Synthesis and characterization of new monomers;
(2) Synthesis of homopolymers and copolymers with methyl acrylate;
(3) Characterization of the polymers.
The monomers were synthesized by reacting HFAB with an robromo-alkene in the presence of an aprotic solvent (DMF) and a strong base (NaH). After purification of the intermediate ether by column chromatography, it was transformed to an alcohol by hydroboration. The monomers were synthesized by reacting the corresponding alcohol with acryloyl chloride in the presence of a tertiary amine using tetrahydrofuran as solvent. Purification of the crude monomers by column chromatography provided them as clear, colorless liquids in yields up to 55% and with purities of 98% as determined by gas chromatography. The homopolymers and copolymers were synthesized by the solution, free radical polymerization technique using azobisisobutyronitrile (AIBN) as the initiator.
The second phase of the research was to study the thermal properties by TGA and DSC. The thermal stabilities of the polymers were as high as 380°C in nitrogen, and the glass transition temperatures were lower (11 °C to -2°C) than the previously studied sterically crowded derivatives. These polymers had viscosities ranging from 0.23 to 0.76 dL/g.
Description
Keywords
acrylates, fluoropolymers, monomers, polymerization
Citation
Oba, J. B. K. (1999). The synthesis and characterization of new, fluoride-containing polyacrylates derived from 2-hydroxyhexafluoroisopropylbenzene (Unpublished thesis). Southwest Texas State University, San Marcos, Texas.