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Self-Exfoliating and Reactive Polymer (SERP) as A Protection Against Chemical Warfare Agents (CWAs)

According to the US army report, there are still significant numbers of stockpiles of chemical warfare agents (CWAs) produced during the Second World War. CWAs production and stockpiling were officially outlawed by the Chemical Weapons Convention of 1993. Nevertheless, some fanatics around the world use CWA as a weapon of mass destruction, such as the Sarin gas attack in Syria in 2013. Since the discovery that toxic pentavalent organophosphorus (OP) compounds has facilitated the development of CWAs as well as insecticides, research on developing protective materials against those toxins have become a priority. Simply, those poisonous molecules are referred to as a “nerve agent” because it prevents nervous system from transferring messages by forming a covalent bond with nerve enzyme, referred to as acetylcholinesterase. As a result of this chemical interference, organs are tightly constricted and muscles cannot relax displying noticeable physical symptoms: contraction of the pupils, excessive mucus, tears and sweat, nausea, vomiting, chest tightness, loss of bowel control like urinating and defecating, and eventually coma or death. Remarkably, even trivial amount of toxins (LD50: ~10 µg/kg) is enough to cause those severe results. Those OP-based compounds can be facilely hydrolyzed by strong base, such as sodium hydroxide and converted to non-toxic compounds. However, this chemical reaction is highly vigorous, generating excess heat. Therefore, it is important to develop a mild catalyst, which can be employed in fabrics or mask for protective garment applications. This can be achieved by selecting organo-based, nucleophiles such as amines, or pyridine-aldoxime. With these organo-based nucleophilic materials, it may be possible to fabricate personal protective equipment to prepare for sudden CWA attacks. The ultimate goal of this project is the fabrication of a protective polymer which can be easily coated on fabric, essentially creating a “second skin”. Protection can be achieved by blocking permeation of toxins through layer and simultaneously detoxifying molecules through chemical modification Furthermore, we challenge ourselves to regenerate fresh reactive layers by physically destructing contaminated area, referred to as a self-exfoliation. Chapter 1 briefly describes the concept of self-exfoliating and reactive polymer (SERP) layer as a protection against CWAs and how to experimentally accomplish and evaluate. Chapter 2 introduces a stimuli-responsive, self-exfoliating polymer with promising acid-sensitive, acetal/ketal-based crosslinkers that exhibit self-exfoliation at room temperature. Synthesis of acid-sensitive crosslinker and their acid-hydrolysis kinetics were studied. Chapter 3 focuses on developing a nucleophilic polymer as a CWA reactant to decontaminate organophosphate-based nerve agents. Chapter 4 evaluates a reactive polymer layer by investigating moisture-vapor transmission rate (MVTR), permeation of nerve agents through polymer films by using Surface-Enhanced Raman Spectroscopy (SERS). Chapter 5 describes conclusions and future work.
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