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Advanced Synthetic Routes to Chemically Recyclable Polyacetals.

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	Advanced Synthetic Routes to Chemically Recyclable Polyacetals./
Author:	Hester, Holley Grace.
Description:	1 online resource (142 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 85-03, Section: B.
Contained By:	Dissertations Abstracts International85-03B.
Subject:	Organic chemistry. -
Online resource:	click for full text (PQDT)
ISBN:	9798380317610

Advanced Synthetic Routes to Chemically Recyclable Polyacetals.
Hester, Holley Grace.

Advanced Synthetic Routes to Chemically Recyclable Polyacetals. - 1 online resource (142 pages)

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

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

Includes bibliographical references

Polyacetals 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.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2024

Mode of access: World Wide Web

ISBN: 9798380317610Subjects--Topical Terms:

1148722
Organic chemistry.
Subjects--Index Terms:

Chemical recyclingIndex Terms--Genre/Form:

554714
Electronic books.

Advanced Synthetic Routes to Chemically Recyclable Polyacetals.
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520 $a Polyacetals 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.
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