Polymer Chemistry Commons^™

The Synthesis And Application Of Polyglyoxylamides, Quinton Ea Sirianni

Electronic Thesis and Dissertation Repository

Self-immolative polymers (SIPs) are a subset of degradable polymers that can be triggered to fully depolymerize with a single stimulus event. This amplifying behaviour makes them ideal for real-world applications including sensors, recyclable plastics, and drug delivery vehicles. Polyglyoxylates (PGs) are a class of SIPs that can be synthesized in a one-pot reaction and designed to respond to different stimuli including light, heat, reduction, and oxidation. However, with the exception of poly(ethyl glyoxylate) (PEtG), the various glyoxylate monomers must be prepared and purified before polymerization, which can be difficult. Furthermore, PGs typically possess properties such as water-insolubility and low glass …

Stimuli-Responsive Polyelectrolytes: Thermosensitive Zwitterionic Polymers And Charged Shape-Changing Star Molecular Bottlebrushes, Evan M. Lewoczko

Doctoral Dissertations

This dissertation work investigated two classes of stimuli-responsive polyelectrolytes: thermosensitive zwitterionic poly(sulfobetaine methacrylate)s (PSBMAs) and charged shape-changing star molecular bottlebrushes (SMBs). While zwitterionic polymers are explored for numerous applications, their structure-solution behavior relationship was poorly understood. The first part of this dissertation focused on the effects of N-substituents of PSBMAs on their behavior in water. A series of PSBMAs were synthesized, with systematically changed N-substituents, including symmetric N-n-alkyl substituents of various lengths and asymmetric N-substituents comprising one methyl and either one cyclohexyl, phenyl or 2-hydroxyethyl group. The behavior of PSBMAs with symmetric N-substituents …

Designing Stimuli-Responsive Nanocomposites To Investigate Interface Dynamics, Huyen Vu

Doctoral Dissertations

Inspired by nature, this research focuses on designing multifunctional renewable nanocomposites with high toughness and stimuli-responsiveness. In recent years, cellulose nanocrystals (CNCs) have been explored due to their abundance, renewable resource, and unique mechanical strength and structural coloration. CNCs naturally self-assemble into the helicoidal (Bouligand) structure that effectively endure high impacts but is brittle without an attendant soft phase. A thermoresponsive polymer, poly(diethylene glycol methyl ether methacrylate) (PMEO₂MA), was incorporated into CNCs via evaporation-induced self-assembly to improve toughness of the resulting nanocomposites and to study responses in polymer dynamics under varying temperature and humidity conditions. To study microscopic …

Self-Immolative Polymers As A Degradable And Triggerable Class Of Surfactants, Siamak Keshtpour

Electronic Thesis and Dissertation Repository

Self-immolative polymers (SIPs) are degradable polymers that undergo end-to-end depolymerization upon triggering. They have potential for the development of degradable surfactants addressing human and environmental toxicity concerns associated with non-degradable surfactants, but they have not yet been investigated as surfactants. Herein, polyglyoxylamide SIPs with different pendent groups and end-caps were synthesized, envisioning they could serve as depolymerizable analogues of poly(vinyl alcohol) and its derivatives. Polyglyoxylamides with pendent hydroxyls stabilized both PEA and PLA particle suspensions. They showed the potential to undergo triggered degradation, resulting in destabilization of the suspensions. However, untriggered suspensions exhibited poor long-term stability, so further structural tuning …

Dually Responsive Shape-Changing Linear And Star Molecular Bottlebrushes With Bicomponent Side Chains, Ethan Wesley Kent

Doctoral Dissertations

Molecular bottlebrushes (MBBs) can exhibit large conformational changes from wormlike to globular in solution in response to environmental stimuli. However, the instability of the collapsed state has prevented shape-changing MBBs from potential applications in, e.g., biomimetic catalysis and substance delivery. This dissertation work focused on dually responsive linear and star MBBs composed of bicomponent side chains in the form of either homografted diblock copolymer or binary heterografted polymeric side chains. When one polymer component collapsed, driving the shape changing of MBBs, another component served as a stabilizer. When both components in the side chains were stimuli-responsive, an additional level of …

Modulating Nanoparticle-Protein Interactions Through Covalent Or Noncovalent Approach For Biomedical Applications, Jingjing Gao

Doctoral Dissertations

Discoveries at the interface of chemistry, biology, and materials science have emerged as a powerful route to impact life science in this century. My research in the Thayumanavan group is focused on problems at this interface. A common theme of all the six projects is the use of modern synthetic organic chemistry to build interesting, novel macromolecules which are chemically rich, to study the molecular self-assembly behavior in solution and then translate to solve problems in the biomedical area. By addressing the design challenge to prepare novel amphiphiles with desired functional groups, controlled molecular weight and the ability to respond …

Plant Stimuli-Responsive Biodegradable Polymers For The Use In Timed Release Fertilizer Coatings, Spencer Heuchan

Electronic Thesis and Dissertation Repository

The use of nitrogen-based fertilizers continues to accelerate with human population growth and increases in global food requirements. Enhanced efficiency fertilizers (EEFs) have been developed to improve the synchronization between nutrient supply and crop nutrient demand. However, many of the current controlled release fertilizers are coated with non-degradable polymers that contribute to accumulation of microplastics within ecosystems. This thesis describes research towards the development of a new class of fertilizer coatings using a self-immolative polymer known as poly (ethyl glyoxylate) (PEtG). PEtG itself does not have suitable properties to produce a viable coating but once blended with another degradable polyester …

Biocompatible, Responsive Polysoaps Via Raft Copolymerization For The Delivery Of Model Cancer Therapeutics, Mason Dearborn

Honors Theses

Many chemotherapeutic drugs are small, hydrophobic molecules that require water-soluble, biocompatible nanocarriers for enhanced vascular circulation. Existing polymeric carriers either conjugate the drug along a copolymer backbone or sequester drugs within a protected interior domain to be delivered to specific sites in the body. Such therapeutic systems must overcome a myriad of hurdles, beginning with complex, multi-step syntheses, followed by other inherent barriers that limit the efficiency of drug delivery at the targeted site. This work aims to circumvent a number of these issues using biocompatible, stimuli-responsive polysoaps that are capable of unimeric micelle formation, hydrophobic drug delivery, and triggered …

Design And Synthesis Of Stimuli-Responsive Polymeric Nanogels Towards Therapeutic Translation, Mallory R. Gordon

Doctoral Dissertations

In the application of delivery of therapeutics, nanostructures of various composition have been employed due to their capacity to act as a host for lipophilic payloads. Advances in the synthetic preparation, size, morphology, and chemical or physical characteristics of polymers have impacted their development and versatility. A detailed understanding of polymeric nanoparticle host-guest properties is crucial to their practical translation to specific delivery applications. Further, these features must be highly tailorable to overcome biological barriers, stably encapsulate their therapeutic contexts, and exhibit payload release selectively in the target environment. In this dissertation, we aim to rationally design polymeric nano-scale assemblies …

End-Capping Strategies For Triggering End-To-End Depolymerization Of Polyglyoxylates, Bo Fan, John Trant, Elizabeth Gillies

Chemistry Publications

Polymers that undergo end-to-end depolymerization in response to the cleavage of a stimuli-responsive end-cap are promising for diverse applications from drug delivery to responsive coatings and plastics. It is critical that the end-cap is designed to respond to an appropriate stimulus for the application. In the current work, end-caps for triggering the depolymerization of poly(ethyl glyoxylate) (PEtG) were explored. First, a phenylboronate, a disulfi de, and an azobenzene were utilized to impart redox-responsive properties to PEtG. Then, methoxy-substituted trityl groups were used to provide sensitivity to mild acid. A multiresponsive platform was also introduced, allowing PEtG to respond to multiple …

Photocontrolled Degradation Of Stimuli-Responsive Poly(Ethyl Glyoxylate): Differentiating Features And Traceless Ambient Depolymerization, Bo Fan, John Trant, Rebecca Yardley, Andrew Pickering, Francois Lagugne-Labarthet, Elizabeth Gillies

Chemistry Publications

The depolymerization of coatings prepared from a 6-nitroveratryl carbonate end-capped poly(ethyl glyoxylate) (PEtG) self-immolative polymer was studied. This polymer undergoes end-to-end depolymerization following cleavage of the end-cap by UV light. Several important fundamental diff erences between this class of polymers and conventional degradable polymers were revealed. For example, polymer backbone cleavage and depolymerization exhibited different dependencies on pH, emphasizing the decoupling of these processes. Probing of the coating erosion mechanism illustrated an interesting combination of features from surface erosion and bulk degradation mechanisms that arise from the end-to-end depolymerization mechanism and further differentiate these polymers from convention degradable polymers. It …

Addressing The Issues Of Drug Delivery Via Advanced Macromolecular Design, Brooks Allen Abel

Dissertations

The work described in this dissertation focuses on the development of synthetic approaches toward novel polymer architectures that specifically address the issues of in vivo drug delivery. Successful implementation of the synthetic methodologies described herein required fundamental investigations into the underlying chemistries in ways that now provide greater insights into the nature of the these chemical reactions.

In Section I, the synthesis of tunable pH- and CO₂-responsive sulfonamide-containing polymers using reversible addition-fragmentation chain transfer (RAFT) polymerization is described. Initially, poor polymerization control of methacryloyl sulfonamide (MSA) monomers was observed using traditional RAFT polymerization conditions. Ultimately, reducing the polymerization …

Raft Synthesis Of Water-Soluble, Stimuli-Responsive Ab Diblock Copolymers, Ran Wang

Dissertations

A series of water-soluble, stimuli-responsive AB diblock copolymers were synthesized via the reversible addition-fragmentation chain transfer (RAFT) polymerization technique employing 2-(2- carboxyethylsulfanylthiocarbonylsulfanyl)propionic acid (CTA26) as the RAFT mediating agent.

First, a series of diacid functional trithiocarbonate chain transfer agents (CTA's) were synthesized and examined for their effectiveness as mediating agents in controlling the polymerization of «-butyl acrylate (nBA). Overall, CTA26 demonstrated good control in the homopolymerization of nBA with respect to the molecular weight and the molecular weight distribution, as well as its ability to form block copolymers with high reinitiating efficiency, and thus was chosen as the CTA for …