Date of Completion
7-22-2016
Embargo Period
7-25-2016
Major Advisor
Douglas H. Adamson
Associate Advisor
Alexandru D. Asandei
Associate Advisor
Kelly A. Burke
Associate Advisor
Eugene Pinkhassik
Associate Advisor
Edward J.Neth
Field of Study
Chemistry
Degree
Doctor of Philosophy
Open Access
Campus Access
Abstract
Polymer brushes are polymers densely tethered to a surface with applications including colloidal stability, biocompatibility, and low-friction surfaces. Here we introduce a fundamentally new approach to the synthesis of surface bound polymer brushes. This approach, which we term “grafting-through” uses surface-initiated atom transfer radical polymerization (ATRP) with monomer supplied through a porous membrane surface rather than from the surrounding solution, creating dense and uniform polymer brushes on the membrane surface. This approach avoids the growth of very long chains while promoting the growth of shorter chains by reversing the monomer concentration gradient created in other brush synthesis approaches. This results in the shorter growing chains experiencing a higher local monomer concentration than longer chains, thus speeding their growth relative to the longer ones. We show by AFM that brushes made by this method are thicker and have less roughness than brushes made by a grafting-from approach. Coarse-grained molecular dynamics simulations show that it is possible to obtain a brush layer with a chain dispersity index approaching unity for sufficiently long chains. FTIR, contact angle measurements, SEM, and kinetic studies are used to characterize and elucidate the growth mechanism of brushes synthesized by the new grafting-through strategy. In other investigations, we introduce a new method of synthesizing a conductive porous hydrogel based on graphene-stabilized emulsions. Conventional methods for making conductive hydrogels normally rely on the use of intrinsically conducting polymers (ICPs). Due to limitations of ICPs, such as low solubility and hydrophilicity, the inexpensive and non-toxic carbon allotrope graphite, is an attractive candidate for producing conductive hydrogels. We synthesize a novel type of hydrogel foam containing a continuous graphitic network by taking advantage of the stabilization of a water-in–oil emulsion in the presence of pristine overlapped graphene sheets. The pore size and distribution, swelling behavior, conductivity and mechanical properties of this hydrogel are characterized. Our approach offers an easy, inexpensive, and tunable way of synthesizing biodegradable conductive hydrogels.
Recommended Citation
Mohammadi Sejoubsari, Reihaneh 4864900, "Self-Assembled Biocompatible Polymers at Interfaces" (2016). Doctoral Dissertations. 1144.
https://digitalcommons.lib.uconn.edu/dissertations/1144