Session: 16-01-01: Poster Session: NSF-Funded Research (Grad & Undergrad)

Paper Number: 99634

99634 - Allylic Bromination and Subsequent Polymer Grafting via Atrp to Control Macromolecular Architecture 

Control over macromolecular architecture and chemical functionality allows for tunability of polymer material properties, such as mechanical performance and ionic conduction. These properties can be controlled by modifying the polymerization method to create different architectures such as linear, grafted, or even miktoarm star polymers, while modifying the polymer chemistries to synthesize different materials with desirable properties. It is one thing to design polymers with these inherent traits from the start, but one current challenge is tailoring pre-existing polymers via post-polymerization methods to address plastic waste. New chemical methodologies are necessary to open alternative pathways, leading to desirable materials from a single starting material and promotes sustainability by finding new and improved uses for commodity polymers. Here, we present an effective post-polymerization functionalization method to synthesize grafted poly(butadiene) (PBD) via allylic bromination and subsequent atom transfer radical polymerization (ATRP) grafting.

In this work we show control over the molecular architecture by tuning graft density and graft length. It is shown here that graft density can be tuned by adjusting the amount of allylic bromine functionalized sites along the initial polymer backbone. The graft length was shown to be controlled via ATRP by altering the monomer to macroinitiator ratio. Furthermore, the use of ATRP allows for tailoring polymer graft chemistry to adequately control the chemical functionality of the materials. By using various monomers such as methyl acrylate and poly(ethylene glycol) methacrylate (PEGMA), it is possible to graft different polymer chemistries to the starting backbone to configure the material for different applications, such as increased mechanical stiffness and hydrogel formation.

Additionally, we have shown that the same allylic bromination and subsequent ATRP reaction can be used for a block copolymer with a poly(butadiene) midblock, poly(styrene)-b-poly(butadiene)-b-poly(styrene) (SBS) to produce grafted polymers with tunable graft density, graft length, and desirable properties due to the different polymer graft chemistries. Using these block copolymers, it is also possible to control material nanostructure as we observe nanostructural transitions from the initial neat polymer to the grafted polymer, as confirmed with small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM).

The work presented here demonstrates a novel and tunable post-polymerization functionalization method to convert commercially available polymers and modify their material properties to be more desirable for a vast number of applications. The post-functionalization and subsequent polymerization process will lead to new avenues of sustainability as we focus on polymer upcycling to meet the demands of materials with desired properties.

Funds: NSF CAREER DMR 1942508

Presenting Author: Vincent Torres Penn State

Presenting Author Biography: Vincent Torres is a graduate student in the department of chemistry, working in the Hickey research group at Penn State University. Here, he investigates new methods of polymerization chemistries to allow for polymer upcycling of common commodity polymers. Vincent received his B.S in chemistry from Albright College, working under Dr. Matthew Sonntag in investigating how doping borosilicate glass with alkali ions affects the glass structure. He has also worked under John Badding at Penn State University, investigating high pressure chemical vapor deposition of cobalt in super critical CO2.

Authors:

Vincent Torres Penn State
Robert Hickey Pennsylvania State University