Non-Stick Length of Polymer-Polymer Interfaces under Small-Amplitude Oscillatory Shear Measurement.

Area of Science:

• Soft Matter Physics
• Materials Science
• Rheology

Background:

• Interfacial behavior in soft materials significantly impacts overall system rheology.
• Standard models often assume non-slip or stick boundary conditions, which may not hold true.
• Excess interface rheology requires specific detection techniques.

Purpose of the Study:

• To develop and validate detection techniques for excess interface rheology.
• To introduce a quantitative measure for interfacial slip and stick phenomena.
• To characterize the rheological response of soft material interfaces.

Main Methods:

• Utilizing small-amplitude oscillatory shear (SAOS) measurements.
• Analyzing the dynamic shear response of stacked polymer bilayers sheared parallel to the interface.
• Calculating the deviation of the bilayer shear modulus from the superposition of component layer moduli.

Main Results:

• A frequency-dependent non-stick length was introduced to characterize excess interface rheology.
• Observed approximate stick response at interfaces of chemically similar polymers.
• Detected apparent slip at interfaces between immiscible polymers.

Conclusions:

• The proposed non-stick length in SAOS effectively detects apparent interfacial slip.
• The non-stick length is a versatile tool applicable to various soft material interfaces.
• This method provides a convenient way to characterize excess interface rheology.