Studies of Surface Initiated Polymerization using Anchored Organometallic Catalyst
Open Access
- Author:
- Dronavajjala, Krishna D
- Graduate Program:
- Chemical Engineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- July 12, 2007
- Committee Members:
- Henry C Foley, Committee Chair/Co-Chair
David Lawrence Allara, Committee Member
Andrew Zydney, Committee Member
Michael Pishko, Committee Member
Ayusman Sen, Committee Member - Keywords:
- anchored organometallic catalyst
Polymer brush
Surface initiated polymerization
Pd (II) catalyst for polymerization - Abstract:
- Surface initiated polymerization (SIP) has potential applications in coatings, microelectronics, sensors and bioadhesion. This is a promising bottom up approach of fabrication where the surface is engineered with molecular precision. In the search to find the simplest and reliable method to grow in-place synthesis of polymerization a novel cationic SIP method was developed. In this, cyano-terminated self-assembled monolayer on a gold surface was used to anchor a highly active cationic Pd organometallic initiator by ligand exchange. The surface concentration of anchored Pd catalyst was determined by XPS to be 0.30±0.05 sites/nm2. Ultrasmooth poly(4-methoxystyrene) brushes with excellent control in thickness at room temperature were grown. In-place growth of brushes was demonstrated by patterning lines of nitrile SAM on gold by soft lithography and the eventual growth of patterned polymer lines. Furthermore, the difference in activity of immobilized Pd organometallic catalyst on gold was compared with the homogeneous counterpart and it was found out that the surface anchored catalyst showed lower activity compared to the homogeneous catalyst. This trend is similar to that observed with other immobilized metal catalyst systems in the literature. Additionally, ultrasmooth polyacetylene and polyphenylacetylene brushes are grown on gold surface at room temperature. Such polymer brushes of conducting materials as potential applications in sensors and solar cells. The concept of anchoring cationic Pd organometallic catalyst by ligand exchange has been extended to Silicon wafers and Superclean Glass substrates. This was done by functionalizing these surfaces with nitrile terminated alkyl siloxanes and then immobilizing the Pd catalyst by ligand exchange. The growth of smooth and homogeneous poly(4-methoxystyrene) and polyacetylene brushes on different substrates establishes the fact that the this method is versatile to be used on any surface for desired applications.