Poly(exo-5-hydroxynorbornene): Structural Characterization and Property Evaluation of Various Cis-Trans Isomer Compositions

Poly(exo-5-hydroxynorbornene) was synthesized via ring-opening metathesis polymerization of an organoborane derivative of norbornene. The polyborane was oxidized by using alkaline H₂O₂ to give the hydroxy polymer. With the objective of controlling the spatial orientation of the hydroxyl groups on the polymer backbone, polymers with different cis-trans contents were synthesized by different polymerization catalysts. The structural characterization of these polymers was done by using IR, ¹H NMR, and ¹⁸C NMR spectroscopy. The molecular structure details will be discussed in terms of sequence distribution of cis-trans and head-tail diads. The thermal properties and molecular orientation of various isomeric structures were evaluated by DSC and two-dimensional surface studies at the air-water interface separately. Surface area measurements show that the polymer backbone with cis structure has significantly higher rigidity than that of the corresponding trans form.