Presentation Title

Acid Catalyzed Oxa-Michael Liquid Crystal Elastomer Synthesis: A Modular System

Start Date

November 2016

End Date

November 2016

Location

Watkins 1111

Type of Presentation

Oral Talk

Abstract

Liquid crystal elastomers (LCEs) are a type of soft material that display order and elasticity. In 2015, the Yakacki group at the University of Colorado at Denver developed a procedure to synthesize a tailorable and programmable LCE using a two-stage thiol acrylate Michael addition and photopolymerization (TAMAP). Nearly any diacrylate, and any di- and tetra-thiol can be used to make an elastomer making this synthesis highly modular. Changing the ratio of monomers affects liquid crystallinity and LCE crosslink density. Adding new thiol or acrylate monomers can add additional functionality to the LCEs. Thiols, however, are difficult to synthesize di- and tetra-functional thiols or to find commercially. Additionally most of these low molecular weight thiols have an extremely low odor threshold (around 0.011 ppm). In contrast, terminal alcohols are effectively odorless, more shelf-stable, and available commercially in much larger varieties. Taking advantage of the oxa-Michael addition mechanism, these terminal alcohols may provide a viable substitute for the thiol monomers to create a system with even greater modularity. Through a qualitative screening process,triflic and tosyl acid catalysts were found to successfully catalyze the polymerization and crosslinking of a model diacrylate with di- and tetra-functional terminal alcohols. Both traditional heating and microwave radiation were required to activate the reaction along with the acid catalysts. FTIR spectroscopy is being used to first confirm the oxa-Michael reaction, and then to monitor reaction kinetics over time.

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Nov 12th, 10:45 AM Nov 12th, 11:00 AM

Acid Catalyzed Oxa-Michael Liquid Crystal Elastomer Synthesis: A Modular System

Watkins 1111

Liquid crystal elastomers (LCEs) are a type of soft material that display order and elasticity. In 2015, the Yakacki group at the University of Colorado at Denver developed a procedure to synthesize a tailorable and programmable LCE using a two-stage thiol acrylate Michael addition and photopolymerization (TAMAP). Nearly any diacrylate, and any di- and tetra-thiol can be used to make an elastomer making this synthesis highly modular. Changing the ratio of monomers affects liquid crystallinity and LCE crosslink density. Adding new thiol or acrylate monomers can add additional functionality to the LCEs. Thiols, however, are difficult to synthesize di- and tetra-functional thiols or to find commercially. Additionally most of these low molecular weight thiols have an extremely low odor threshold (around 0.011 ppm). In contrast, terminal alcohols are effectively odorless, more shelf-stable, and available commercially in much larger varieties. Taking advantage of the oxa-Michael addition mechanism, these terminal alcohols may provide a viable substitute for the thiol monomers to create a system with even greater modularity. Through a qualitative screening process,triflic and tosyl acid catalysts were found to successfully catalyze the polymerization and crosslinking of a model diacrylate with di- and tetra-functional terminal alcohols. Both traditional heating and microwave radiation were required to activate the reaction along with the acid catalysts. FTIR spectroscopy is being used to first confirm the oxa-Michael reaction, and then to monitor reaction kinetics over time.