Surface-initiated ring opening metathesis polymerization from the vapor phase to prepare compositionally versatile thin films

Abstract

Functional polymer films provide the ability to tailor the properties of surfaces. Ring opening metathesis polymerization (ROMP) is a powerful polymerization technique that provides rapid kinetics and substantial control over the polymerization. However, the development of functional polymer films by surface-initiated ROMP (SiROMP) is limited because of the relatively low number of available monomers. Thus, finding accessible new methods that can impart multiple functionalities to polymer films grown by SiROMP is critical. This dissertation describes the work that I have performed in introducing multiple functionalities and properties into polymer thin films prepared by SiROMP.

I report the SiROMP of trans-5-norbornene-2,3-dicarbonyl chloride (NBDAC) from the vapor phase as a versatile platform to achieve many functional polymer films via simple exposure of the pNBDAC film to reagents. This modification strategy owes to the fast and high-yield reactions of acyl chlorides with alcohols, amines, water, and other molecules. The compositionally versatile platform is applied to produce polynorbornene films that contain pendant hydroxamic acid groups, which show ability to chelate transition metal ions and can be used in metal ion caption from aqueous solutions. The chelated metals within the polymer film act as cross-linkers, which remarkably enhance the pH stability, thermal stability, and resistance against ion transfer of the original film. Another application of this compositionally versatile pNBDAC platform is to produce pH-responsive, ester/carboxylic acid random copolymer films, which demonstrate the ability of these films to have multiple functionalities introduced. The magnitude and range of the pH-responsive performance are controllable by designing the ester/carboxylic acid composition in the film.

Part of the dissertation examines another compositionally versatile platform through the preparation of polymer/ionic liquid (IL) composite films. Instead of chemically modifying the polymer films, the film properties can also be altered by the physical or electrostatic incorporation of other materials within the polymer framework. A polymer/ IL gel film can be prepared by incorporating ILs into surface-initiated poly(dicyclopentadiene)(pDCPD) films using a simple immersion method. This novel processing approach is proven to be feasible in preparing polymer/IL gel films with various IL species.