Polymer-solvent interaction and conformational changes at a molecular level: Implication to solvent-assisted...

Area of Science:

• Polymer Science
• Surface Chemistry
• Materials Science

Background:

• The chemical structure of polymers dictates their physical and chemical properties.
• Understanding polymer-solvent interactions is crucial for predicting material behavior in various applications.
• Surface properties and molecular orientations are key determinants of interfacial phenomena.

Purpose of the Study:

• To investigate how monomeric unit variations in polymers affect surface structure and molecular orientations.
• To explore the influence of solvent chemical affinity on polymer film response.
• To correlate structural changes with interfacial processes like adsorption and swelling.

Main Methods:

• Sum Frequency Generation (SFG) spectroscopy to analyze molecular orientations.
• Contact angle goniometry to assess surface wettability.
• Atomic Force Microscopy (AFM) to image surface topography.
• Molecular simulations to support experimental findings.

Main Results:

• SFG confirmed molecular re-organization at polymer surfaces exposed to different solvents.
• AFM revealed homogeneous flatness in CDCl3 and swollen regions in D2O.
• Solvent exposure led to surface imprinting, deformation, and aggregation.
• Polymer surface conformation changed based on solvent chemical affinity.

Conclusions:

• Monomer structure significantly influences polymer film surface behavior and interfacial molecular group orientation.
• Solvent properties dictate the nature of polymer-solvent interfacial interactions, leading to distinct surface responses.
• These findings have implications for controlling adsorption, permeation, swelling, deformation, and aggregation in polymer systems.