skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: Property impact of common linker segments in sequence-controlled polyesters
Heterogeneous “linkers” are incorporated into polymers for a number of reasons, most commonly to facilitate the coupling of the targeted backbone segments. Due to their inclusion in the backbone, these linkers have the potential to affect the overall properties of the copolymer, even when present in relatively low weight percentages. To characterize the degree of impact of some common linkers, a set of polymers that incorporate both degradable sequenced segments and linkers were synthesized and systematically examined. Seven sequence-controlled olefin containing ester macrocycles were prepared, each with a unique central moiety, including a five-carbon alkyl chain, diethylene glycol, a urea, a thioether, a triazole, a bioaromatic, and an extension of the ester sequence. The macrocycles were polymerized via ED-ROMP to yield seven polymers that vary only in the the linker segment. The properties of all polymers were compared to determine the relative dominance of the different linker types. The properties tested in the study included thermal behavior, mechanical characteristics, hydrolytic degradation and film qualities. The thermal and mechanical properties proved to be dependent primarily on the ability of the linker to promote interchain interactions, as well as the weight fraction of the linker, whereas the hydrolytic degradation was dominated by the relative hydrophobicity of the linker groups. In all cases, the linker identity was a significant contributer to the behavior.  more » « less
Award ID(s):
1709144 1625002
PAR ID:
10110921
Author(s) / Creator(s):
; ;
Date Published:
Journal Name:
Polymer Chemistry
Volume:
10
Issue:
2
ISSN:
1759-9954
Page Range / eLocation ID:
244 to 252
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; (, Polymer Chemistry)
    null (Ed.)
    Poly(ester-amide)s (PEAs) have been prepared from (glucose-derived) β-methyl-δ-valerolactone (MVL) by reaction of MVL-derived diamidodiols with diacid chlorides in solution to form poly(ester-amide)s having alternating diester-diamide subunits. The PEAs formed by this method exhibit plastic properties and are of sufficiently high molecular weight to be tough, ductile materials (stress at break: 41–53 MPa, strain at break: 530–640%). The length of the methylene linker unit ( n = 1,2,3) between amide groups of the diamidodiols affects the Young's modulus; longer linkers reduce the stiffness of the materials. This allows tuning of the properties by judicious choice of precursors. MVL was also converted to a diacid chloride that was then used to prepare a PEA that is 76 wt% MVL-derived. The degradation rates of suspensions of these new PEAs in basic aqueous media were benchmarked and their instability in aqueous acid was also observed. NMR studies were used to detect the hydrolytic degradation products of both these PEAs as well as a structurally simpler analog. 
    more » « less
  2. ; ; ; (, ChemSusChem)
    Abstract Design strategies to achieve degradation and ideally closed‐loop recycling of organic semiconductors have attracted great interest in order to minimize the electronic waste (E‐waste). In this work, three ester‐incorporated monomers were synthesized by the names of Thiophene‐Ester‐Ethylene‐Thiophene (TEET), Thiophene‐Ester‐Methylene‐Thiophene (TEMT), and Thiophene‐Ester‐Thiophene (TET), which were co‐polymerized via Stille polycondensation with a benzodithiophene (BnDT) π‐conjugated unit to yield a series of ester‐incorporated polymers: PBnDT‐TEET, PBnDT‐TEMT, and PBnDT‐TET. While the ester‐only linker can maintain some extended conjugation in PBnDT‐TET, the other two ester linkers having conjugation breaking units result in isolated conjugated segments in PBnDT‐TEET and PBnDT‐TEMT, evidenced by UV‐Vis and CV results. This yields an improved photovoltaic performance of PBnDT‐TET compared to PBnDT‐TEET. While all three polymers can depolymerize under methanolysis, the alternating co‐polymer PBnDT‐TEET demonstrates the highest recyclability potential with a single dimethyl ester‐functionalized product with an excellent 92 % isolated yield, which can then be repolymerized to reobtain PBnDT‐TEET with a 36 % yield. This work provides a framework towards achieving recyclable organic semiconductors to reduce E‐waste. Although the incorporation of ester linkers allowed for closed‐loop recycling, the low solar cell efficiency of PBnDT‐TEET highlights the significant challenge in achieving both recycling and high device performance. 
    more » « less
  3. ; ; (, Applied Physics Letters)
    The characteristics of the interface between DNA and metallic carbon nanotube (CNT) in supramolecular assemblies are important to understand for electronic and sensing applications. We study the mechanical stability and electronic properties of these interfaces with amino and ester linkers using computational experiments. Our study demonstrates that both linkers significantly enhance the mechanical stability of DNA–CNT systems, with the DNA adopting a stable and lower energy perpendicular orientation relative to the CNT as opposed to a conventional parallel arrangement. This lower energy configuration is driven by nonbonded interactions between the DNA base and the CNT surface. Our calculations also reveal that interface resistance is primarily governed by DNA–CNT interactions with negligible contribution from the linkers. In the case of the amino linker, we predict a 100-fold transmission ratio between parallel and perpendicular configurations of DNA relative to CNT. This observation can be used to build an electromechanical switch with fast switching times (30 ns). The ester linker, on the contrary, enables a better electronic coupling between the DNA and CNT even when strained. 
    more » « less
  4. ; ; (, Polymer Chemistry)
    Sustainable gas barrier materials, such as polyglycolide, poly(l-lactide), and poly(ethylene 2,5-furandicarboxylate) are important alternatives to traditional plastics used for packaging where low gas permeability is beneficial. However, high degrees of crystallinity in these materials can lead to undesirably low material toughness. We report poly(ester–amide)s derived from glycolide and diamines exhibiting both high toughness and desirable gas barrier properties. These sustainable poly(ester–amide)s were synthesized from glycolide-derived diamidodiols and diacids. To understand the structure–property relationships of the poly(ester–amide)s, polymers with different numbers of methylene groups were compared with respect to thermal, mechanical, and gas barrier properties. As the number of methylene groups between ester groups increased in the even-numbered series, the melting temperature decreased and oxygen permeability increased. We also found that these polymers are readily degradable under neutral, acidic, and basic hydrolytic conditions. These high-performance poly(ester–amide)s are promising sustainable alternatives to conventional gas barrier materials. 
    more » « less
  5. ; ; ; ; (, Polymer Chemistry)
    Thiol–ene photopolymerization was exploited for the synthesis of poly(β-thioether ester ketal) networks capable of undergoing complete degradation under acid and/or basic conditions. Using the design of four novel bisalkene diketal monomers, we demonstrate the ability to tune degradation profiles under acidic conditions with timescales dictated by the structure of the diketal linker, while hydrolysis of the β-thioether ester functionality dominates the degradation profile under basic conditions irrespective of the diketal structure. All four poly(β-thioether ester ketal) networks exhibited degradation behavior characteristic of a surface erosion process. The networks showed mechanical (low modulus) and thermomechanical properties (low T g ) typical of thiol–ene thermosets with minimal influence from the structure of the diketal linkage. To highlight the advantages of endowing a step-growth network with ketal linker chemistry, we demonstrated the ability to recover diketone precursors from the thermoset degradation by-products and recycle these compounds into building blocks for additional thermoset materials. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email