Precision Polymers from Low Strain Cycloalkenes

Regioregularity

 

Having the ability to make precise structure is incredibly important in determining true structure-property relationships. Using low strain cycloalkene and ring-opening metathesis polymerizations (ROMP), precision can be achieved. This is especially prevalent in copolymers where achieving regularity was once difficult to have exact structure. Using cyclopentene, a functional group can be placed on every fifth carbon. The first target of the project was a copolymer of ethylene-styrene (ES). It can be achieved by performing ROMP on 4-phenylcyclopentene followed by mild hydrogenation. 

 

Variable Temperature ROMP
controlling molar mass and dispersity

 

Due to the driving force of ROMP being the release of ring strain, attempting ROMP on low strain cycloalkenes typically leads to difficulties in obtaining high conversions and molecular control. Therefore, we developed a method that overcomes these issues through high temperatures initiation and low temperature propagation which we call VT-ROMP. High molecular weight and low dispersity polypentenamers were produced at targeted molar mass and high conversions for the first time.

Higher Precision Polymers
controlling stereo- and regio-chemistries

 

Gaining control over the stereochemistry and regioregularity of polymers is a historically difficult yet sought after task. A methodology, using bulky allylic substituents on cyclopentene monomers has recently been developed that allows for control over the tacticity  and regioregularity of the polymer. Hence isotactic branches at every five carbons along a polypentenamer rubber are produced. Such materials are predicted to have complex material and thermal properties which are being investigated.

Department of Chemistry & Biochemistry

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