New Long End-Associative Polymers for Mist Control in I. Aqueous Solutions and II. Hydrocarbon Solvents

Citation

Kim, Hojin (2023) New Long End-Associative Polymers for Mist Control in I. Aqueous Solutions and II. Hydrocarbon Solvents. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/rsx9-qt39. https://resolver.caltech.edu/CaltechTHESIS:08252022-035254306

Abstract

Ultralong linear polymers are well known to be useful in a variety of applications such as mist control, drag reduction, and agricultural spray drift control. However, the application of ultralong linear polymers is limited by shear degradation of the ultralong polymer chains that occurs under strong flow conditions. To overcome the issue of shear degradation, our group previously designed long end-associative polymers that can self-assemble into megasupramolecules (M_w > 2000 kg/mol) in low polarity solvents like jet fuel. The previously developed long end associative polymers had polycyclooctadiene backbones (1,4 polybutadiene) with carboxylic acid or tertiary amine end groups that associated via hydrogen bonding. They were shear degradation resistant and used as mist-control agents that provided fire-protection to jet fuel at concentrations as low as 0.3wt%.

Building upon the previous work, this thesis describes efforts toward expanding the applicability of long end-associative polymers. We first describe the design and synthesis of water-soluble long end-associative polymers for agricultural spray mist-control. We synthesized telechelic polyacrylamides using reversible addition fragmentation chain transfer (RAFT) polymerization. We explored two types of associations that can form stable supramolecules in water: host-guest interactions between adamantane and beta-cyclodextrin (Chapter 1), and metal-ligand association between terpyridine and transition metal ions (Chapter 2). Careful optimization of polymerization conditions allowed the synthesis of ultra-high molecular weight telechelic polyacrylamides with narrow polydispersity. We found that the terpyridine functionalized polyacrylamides with M_w 820 kg/mol could assemble into megasupramolecules (M_w > 2000 kg/mol) upon addition of Fe(II) or Ni(II).

In Chapters 3 and 4, we return to long end-associative polymers in hydrocarbon solvents. In Chapter 3, we tackle the issue of poor solubility of the previous generation of associative PCODs in a highly nonpolar solvent, PAO. In Chapter 4, we develop a new generation of end groups for improved solubility and ease of synthesis.

Finally in Chapter 5, we discuss polyDODT (poly(3,6-dioxa-1,8-octanedithiol)), a polydisulfide that tends to form a mixture of linear and cyclic species. We present new methods to detect the presence of linear species in the mixture, as well as an alternative synthesis route for synthesis of polyDODT.

Thesis Files