Thermal Transitions in Polyelectrolyte Assemblies Occur via a Dehydration Mechanism
Erol Yildirim1, Yanpu Zhang2, Jodie L Lutkenhaus2
1Department of Chemistry, Aalto University, P.O. Box 16100, 00076 Aalto, Espoo, Finland.
ACS Macro Letters
|May 21, 2022
Summary
Dehydration drives the thermal transition in hydrated polyelectrolyte complexes, impacting plasticization and diffusion. Water is essential for this transition, unlike alcohols.
Area of Science:
- Materials Science
- Polymer Chemistry
- Physical Chemistry
Background:
- Hydrated polyelectrolyte (PE) complexes and multilayers exhibit thermal transitions similar to glass transitions.
- Understanding these transitions is crucial for developing advanced molecular materials.
Purpose of the Study:
- To investigate the role of dehydration in the thermal transitions of PE complexes.
- To elucidate the impact of dehydration on plasticization and component diffusion.
Main Methods:
- Combined molecular simulations and differential scanning calorimetry (DSC).
- Studied poly(diallyldimethylammonium) (PDAC) and poly(styrenesulfonate) (PSS) multilayers.
Main Results:
- Established that dehydration is the primary driver of the observed thermal transition.
- Demonstrated that water is required for the transition, as it does not occur in the presence of alcohols.
- Showcased changes in plasticization and diffusion behavior linked to dehydration.
Conclusions:
- Dehydration critically influences the thermal and diffusion properties of hydrated PE complexes.
- Connects PE complexes to thermoresponsive polymers and liquid crystals, highlighting the role of (de)hydration.
- Provides a fundamental link for understanding thermal responses in aqueous molecular materials.
Related Concept Videos
01:15Dehydration Synthesis
144.0K
Overview
Dehydration synthesis (also called a condensation reaction) is the chemical process in which two molecules covalently link together to form a new molecule, along with the release of a water molecule. Many physiologically important compounds form by dehydration synthesis reactions, such as complex carbohydrates, proteins, DNA, and RNA.
Synthesis of carbohydrates
Sugar molecules are covalently linked together by dehydration synthesis. During the reaction, the hydroxyl (-OH) group from...
Dehydration synthesis (also called a condensation reaction) is the chemical process in which two molecules covalently link together to form a new molecule, along with the release of a water molecule. Many physiologically important compounds form by dehydration synthesis reactions, such as complex carbohydrates, proteins, DNA, and RNA.
Synthesis of carbohydrates
Sugar molecules are covalently linked together by dehydration synthesis. During the reaction, the hydroxyl (-OH) group from...
144.0K
00:57Cationic Chain-Growth Polymerization: Mechanism
2.4K
The cationic polymerization mechanism consists of three steps: initiation, propagation, and termination. In the initiation step of the polymerization process, the π bond of a monomer gets protonated by the Lewis acid catalyst, which is formed from boron trifluoride and water. The protonation of the π bond generates a carbocation stabilized by the electron‐donating group. In the propagation step, the π bond of the second monomer acts as a nucleophile and attacks the...
2.4K
02:42Aqueous Solutions and Heats of Hydration
15.1K
Water and other polar molecules are attracted to ions. The electrostatic attraction between an ion and a molecule with a dipole is called an ion-dipole attraction. These attractions play an important role in the dissolution of ionic compounds in water.
When ionic compounds dissolve in water, the ions in the solid separate and disperse uniformly throughout the solution because water molecules surround and solvate the ions, reducing the strong electrostatic forces between them. This process...
When ionic compounds dissolve in water, the ions in the solid separate and disperse uniformly throughout the solution because water molecules surround and solvate the ions, reducing the strong electrostatic forces between them. This process...
15.1K
01:21Polymer Classification: Crystallinity
3.2K
Unlike ionic or small covalent molecules, polymers do not form crystalline solids due to the diffusion limitations of their long-chain structures. However, polymers contain microscopic crystalline domains separated by amorphous domains.
Crystalline domains are the regions where polymer chains are aligned in an orderly manner and held together in proximity by intermolecular forces. For example, chains in the crystalline domains of polyethylene and nylon are bound together by van der Waals...
Crystalline domains are the regions where polymer chains are aligned in an orderly manner and held together in proximity by intermolecular forces. For example, chains in the crystalline domains of polyethylene and nylon are bound together by van der Waals...
3.2K
02:35Acid-Catalyzed Dehydration of Alcohols to Alkenes
21.1K
In a dehydration reaction, a hydroxyl group in an alcohol is eliminated along with the hydrogen from an adjacent carbon. Here, the products are an alkene and a molecule of water. Dehydration of alcohols is generally achieved by heating in the presence of an acid catalyst. While the dehydration of primary alcohols requires high temperatures and acid concentrations, secondary and tertiary alcohols can lose a water molecule under relatively mild conditions.
21.1K
02:34Polymers
37.6K
The word polymer is derived from the Greek words “poly” which means “many” and “mer” which means “parts”. Polymers are long chains of molecules composed of repeating units of smaller molecules, known as monomers. They either occur naturally, such as DNA and proteins, or can be constructed synthetically, like plastics. They have varied structural characteristics, such as linear chains, branched chains, or complex networks, that contribute to the...
37.6K