skip to main content


Title: Complementary Dynamic Chemistries for Multifunctional Polymeric Materials
Abstract

Dynamic materials (DMs) or dynamers have potential applications across a broad range of material science challenges. These applications include sustainable materials as a part of the circular plastics economy, advanced materials with tailored high stress properties and biomedical agents. DMs are comprised of polymers that crosslinked through reversible covalent and noncovalent linking groups. This group provides reversible bonds, which impart properties such as (re)healing, adaptability, toughness into a material. The nature of the linker dictates the dynamer's stability and dynamic properties, although for many applications one linker alone cannot give materials with complex multiresponsive functions. The combination of multiple dynamic linkers can introduce complementary functionalities into a single material. This combination of linkers enhances the collective material properties by matching their strengths and offsetting the weaknesses, or by selecting linkers for specific functions, such as one linker for rapid exchange and the other to respond to external stimuli. This contribution highlights the possibilities and unique features of materials containing multiple dynamic linkers, reviewing both fundamental discoveries of materials possessing multiple dynamic bonds and applications facilitated by the presence of multiple linking group chemistry.

 
more » « less
Award ID(s):
1749730
PAR ID:
10362991
Author(s) / Creator(s):
 ;  ;  ;  ;  
Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
Advanced Functional Materials
Volume:
32
Issue:
8
ISSN:
1616-301X
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. null (Ed.)
    A one pot synthesis is applied to control the chain structure and architecture of multiply dynamic polymers, enabling fine tuning of materials properties by choice of polymer chain length or crosslink density. Macromolecules containing both non-covalent linkers based on quadruple hydrogen-bonded 2-(((6-(3-(6-methyl-4-oxo-1,4-dihydropyrimidin-2-yl)ureido)hexyl)carbamoyl)oxy)ethyl methacrylate (UPyMA), and thermoresponsive dynamic covalent furan–maleimide based Diels–Alder linkers are explored. The primary polymer's architecture was controlled by reversible addition-fragmentation chain transfer (RAFT) polymerization, with the dynamic non-covalent (UPyMA) and dynamic covalent furfuryl methacrylate (FMA) units incorporated into the same backbone. The materials are crosslinked, taking advantage of the “click” chemistry properties of the furan–maleimide reaction. The polymer materials showed stimulus-responsive thermomechanical properties with a decrosslinking temperature increasing with the polymer's primary chain length and crosslink density. The polymers had good thermally promoted self-healing properties due to the dynamic covalent Diels–Alder bonds. Besides, the materials had excellent stress relaxation characteristics induced by the exchange of the hydrogen bonds in UPyMA units. 
    more » « less
  2. Gels made of telechelic polymers connected by reversible cross-linkers are a versatile design platform for biocompatible viscoelastic materials. Their linear response to a step strain displays a fast, near-exponential relaxation when using low-valence cross-linkers, while larger supramolecular cross-linkers bring about much slower dynamics involving a wide distribution of timescales whose physical origin is still debated. Here, we propose a model where the relaxation of polymer gels in the dilute regime originates from elementary events in which the bonds connecting two neighboring cross-linkers all disconnect. Larger cross-linkers allow for a greater average number of bonds connecting them but also generate more heterogeneity. We characterize the resulting distribution of relaxation timescales analytically and accurately reproduce stress relaxation measurements on metal-coordinated hydrogels with a variety of cross-linker sizes including ions, metal-organic cages, and nanoparticles. Our approach is simple enough to be extended to any cross-linker size and could thus be harnessed for the rational design of complex viscoelastic materials.

     
    more » « less
  3. CALF-20, a Zn-triazolate-based metal-organic framework (MOF), is one of the most promising adsorbent materials for CO2 capture. However, competitive adsorption of water severely limits its performance when the relative humidity (RH) exceeds 40%, limiting the potential implementation of CALF-20 in practical settings where CO2 is saturated with moisture, such as post-combustion flue gas. In this work, three newly designed MOFs related to CALF-20, denoted as NU-220, CALF-20M-w, and CALF-20M-e that feature hydrophobic methyl-triazolate linkers are presented. Inclusion of methyl groups in the linker is proposed as a strategy to improve CO2 uptake in the presence of water. Notably, both CALF-20M-w and CALF-20M-e retain over 20% of their initial CO2 capture efficiency at 70% RH – a threshold at which CALF-20 shows negligible CO2 uptake. Grand canonical Monte Carlo (GCMC) simulations reveal that the methyl group hinders water network formation in the pores of CALF-20M-w and CALF-20M-e and enhances their CO2 selectivity over N2 in the presence of high moisture content. Moreover, calculated radial distribution functions indicate that introducing the methyl group into the triazolate linker increases the distance between water molecules and Zn coordination bonds, offering insights into the origin of the enhanced moisture stability observed for CALF-20M-w and CALF-20M-e relative to CALF-20. Overall, this straightforward design strategy has afforded more robust sorbents that can potentially meet the challenge of effectively capturing CO2 in practical industrial applications. 
    more » « less
  4. Abstract

    Dynamic bonds introduce unique properties such as self‐healing, recyclability, shape memory, and malleability to polymers. Significant efforts have been made to synthesize a variety of dynamic linkers, creating a diverse library of materials. In addition to the development of new dynamic chemistries, fine‐tuning of dynamic bonds has emerged as a technique to modulate dynamic properties. This Review highlights approaches for controlling the timescales of dynamic bonds in polymers. Particularly, eight dynamic bonds are considered, including urea/urethanes, boronic esters, Thiol–Michael exchange, Diels–Alder adducts, transesterification, imine bonds, coordination bonds, and hydrogen bonding. This Review emphasizes how structural modifications and external factors have been used as tools to tune the dynamic character of materials. Finally, this Review proposes strategies for tailoring the timescales of dynamic bonds in polymer materials through both kinetic effects and modulating bond thermodynamics.

     
    more » « less
  5. Abstract

    Dynamic bonds introduce unique properties such as self‐healing, recyclability, shape memory, and malleability to polymers. Significant efforts have been made to synthesize a variety of dynamic linkers, creating a diverse library of materials. In addition to the development of new dynamic chemistries, fine‐tuning of dynamic bonds has emerged as a technique to modulate dynamic properties. This Review highlights approaches for controlling the timescales of dynamic bonds in polymers. Particularly, eight dynamic bonds are considered, including urea/urethanes, boronic esters, Thiol–Michael exchange, Diels–Alder adducts, transesterification, imine bonds, coordination bonds, and hydrogen bonding. This Review emphasizes how structural modifications and external factors have been used as tools to tune the dynamic character of materials. Finally, this Review proposes strategies for tailoring the timescales of dynamic bonds in polymer materials through both kinetic effects and modulating bond thermodynamics.

     
    more » « less