Paper Number
SM6 

Session
Polymers Solutions, Melts and Blends

Title
A generalized mechano-statistical transient network model to unravel the network topology, elasticity and relaxation dynamics of associative multiblock copolymer solutions

Presentation Date and Time
October 10, 2022 (Monday) 11:30

Track / Room
Track 2 / Sheraton 3

Authors (Click on name to view author profile)

  1. Huysecom, An-Sofie (KU Leuven, Soft Matter, Rheology and Technology)
  2. Thielemans, Wim (KU Leuven)
  3. Cardinaels, Ruth (KU Leuven, Soft Matter, Rheology and Technology)
  4. Moldenaers, Paula (KU Leuven, Soft Matter, Rheology and Technology)

Author and Affiliation Lines (in printed abstract book)
An-Sofie Huysecom1, Wim Thielemans2, Ruth Cardinaels1 and Paula Moldenaers1
1Soft Matter, Rheology and Technology, KU Leuven, Leuven, Vlaams-Brabant 3001, Belgium; 2KU Leuven, Leuven, Belgium

Speaker / Presenter 
Huysecom, An-Sofie

Keywords
gels; polymer solutions; surfactants

Text of Abstract
The micellar assemblies formed by hydrophobically associating block copolymers in selective solvents are often employed as multifunctional interaction nodes in physical polymer gels. Hydrophilic blocks capped by two hydrophobic blocks have the potential to bridge two different micellar cores which are in close proximity, thereby forming a transient elastic network. Whereas most studies use telechelic triblock copolymers with hydrophobic end groups, our study focuses on alternating PEO-PPO multiblock copolymers with multiple hydrophobic PPO blocks distributed along the chain, giving rise to a multitude of possible chain configurations. Therefore, in this contribution we adopt a combinatorics approach to extend and generalize the mechano-statistical transient network model originally developed by Annable for telechelic triblock copolymers [T. Annable et al., Journal of Rheology, 1993, 37, 695] to alternating multiblock copolymers. By using knowledge about the spatial distribution of the micellar nodes, as inferred from Small-Angle X-ray Scattering, the model allows us to translate microscopic changes in the micellar network topology to macroscopic rheological behavior. Our model predictions of elasticity as a function of concentration show excellent agreement with experimental rheological data. The evolution of the high-frequency plateau modulus and hence the elasticity can be linked to a change in the network topology from loop-dominated with low-functional crosslinking nodes at low concentrations to bridge-dominated with highly functional crosslinking nodes at higher concentrations. The concentration dependence of the relaxation times reveals the importance of the network configurations and overall microstructure on the Sticky-Rouse like relaxation dynamics of the network strands. We believe our transient network model and the ensuing insights can also be useful for other equally-spaced, multi-sticker associating polymers forming networks by multifunctional interactions.