자료유형  

 학위논문

Control Number  

0016933839

International Standard Book Number  

9798380317610

Dewey Decimal Classification Number  

547

Main Entry-Personal Name  

Hester, Holley Grace.

Publication, Distribution, etc. (Imprint  

[S.l.] : Cornell University., 2023

Publication, Distribution, etc. (Imprint  

Ann Arbor : ProQuest Dissertations & Theses, 2023

Physical Description  

1 online resource(142 p.)

General Note  

Source: Dissertations Abstracts International, Volume: 85-03, Section: B.

General Note  

Advisor: Coates, Geoffrey.

Dissertation Note  

Thesis (Ph.D.)--Cornell University, 2023.

Restrictions on Access Note  

This item must not be sold to any third party vendors.

Summary, Etc.  

요약Polyacetals have emerged as a promising class of chemically recyclable materials, thanks to their high thermal stability and capability to undergo triggered depolymerization with a strong acid catalyst. Addressing the global plastic waste crisis requires innovative solutions, and polymers capable of efficient depolymerization to monomers offer a viable closed-loop approach. These polymers facilitate material value retention, reduce the environmental impacts of conventional plastics, and promote a circular economy. In contribution to the development of a closed-loop polymer economy, this work presents new synthetic routes for high-performance polyacetals, specifically poly(1,3-dioxolane), (pDXL), through environmentally friendly and accessible polymerization systems.First, a polymerization system capable of synthesizing ultra-high-molecular-weight (UHMW) pDXL is presented, yielding a chemically recyclable thermoplastic material with impressive mechanical properties. The approach employs cost-effective, nonmetal triethyloxonium salt initiators and a proton trap to achieve UHMW pDXL with molecular weights exceeding 1000 kDa. UHMW pDXL showcases superior mechanical properties in comparison to lower molecular weight counterparts and outperforms ultra-high-molecular-weight polyethylene (UHMWPE) in ultimate stress. The polymerization system provides molecular weight control, making chemically recyclable pDXL of targeted molecular weights accessible without requiring toxic or expensive components. The robust mechanical properties of UHMW pDXL offer an incentive to replace existing commodity plastics with a chemically recyclable alternative. Additionally, the profound enhancement of polymer properties by increasing polymer molecular weight provides a valuable future approach for improving the performance of other sustainable polymers.Following the development of UHMW pDXL, a reversible-deactivation cationic ring-opening polymerization (RD-CROP) of DXL using earth-abundant and affordable halophilic zinc Lewis acids is reported. The Coates group previously reported the RD-CROP of acetals employing indium catalysts; however, indium's scarcity and cost discouraged further development. In this work, RD-CROP with accessible and economical catalytic systems is developed. Four commercially available zinc complexes successfully demonstrated the polymerization of DXL with methoxymethyl halide initiators. This methodology enabled the preparation of pDXL with substoichiometric loadings of ZnCl2, the first example of RD-CROP of dioxolane with catalytic amounts of halophilic Lewis acid. Overall, this dissertation contributes to the development of sustainable polyacetals and their polymerization methods, advancing the field of chemically recyclable materials.

Subject Added Entry-Topical Term  

Organic chemistry.

Subject Added Entry-Topical Term  

Polymer chemistry.

Subject Added Entry-Topical Term  

Materials science.

Index Term-Uncontrolled  

Chemical recycling

Index Term-Uncontrolled  

Circular economy

Index Term-Uncontrolled  

Polyacetal

Index Term-Uncontrolled  

Polydioxolane

Index Term-Uncontrolled  

Polymer

Index Term-Uncontrolled  

Sustainable

Added Entry-Corporate Name  

Cornell University Chemistry and Chemical Biology

Host Item Entry  

Dissertations Abstracts International. 85-03B.

Host Item Entry  

Dissertation Abstract International

Electronic Location and Access  

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Control Number  

joongbu:643961