Paper Number
PO63 

Session
Poster Session

Title
Role of co-solvent composition on the rheology and thermoreversibility of PNIPAM/silyl methacrylate copolymers

Presentation Date and Time
October 12, 2022 (Wednesday) 6:30

Track / Room
Poster Session / Riverwalk A

Authors (Click on name to view author profile)

  1. Linn, Jason D. (University of Minnesota, Twin Cities, Department of Chemical Engineering and Materials Science)
  2. Zhang, Diana Y. (University of Minnesota, Chemical Engineering and Materials Science)
  3. Rodriguez, Fabian A. (University of Texas Rio Grande Valley, Department of Mechanical Engineering)
  4. Calabrese, Michelle A. (University of Minnesota, Chemical Engineering and Materials Science)

Author and Affiliation Lines (in printed abstract book)
Jason D. Linn1, Diana Y. Zhang1, Fabian A. Rodriguez2 and Michelle A. Calabrese1
1Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455; 2Department of Mechanical Engineering, University of Texas Rio Grande Valley, Edinburg, TX 78539

Speaker / Presenter 
Linn, Jason D.

Keywords
polymer solutions

Text of Abstract
Polymers functionalized with inorganic silane groups are used in a wide range of applications due to the silane reactivity enabling the generation of covalently-bonded coatings, micelles, and hydrogels, and bulk structural materials. Utilizing stimuli-responsive polymers in these hybrid systems can lead to smart and tunable behavior for sensing, drug delivery, and optical coatings. Of particular interest is the thermo-responsive polymer poly(N-isopropyl acrylamide) (PNIPAM) functionalized with 3-(trimethoxysilyl)propyl methacrylate (TMA), which has been used in coatings and gels and has demonstrated unique aqueous thermal responses. Processing responsive polymers in different conformations can lead to distinct behaviors in sensors and coatings. However, processing in the collapsed state in aqueous systems can require high temperatures, lead to orders of magnitude increase in viscosity, and cause the formation of films at the solution/air interface. An approach to overcome such limitations is the use of solvent mixtures where one- or two-phase behavior can be accessed over a wide range of temperatures due to co-solvency and co-nonsolvency effects. This work investigates the impact of solvent composition in binary solvent systems on the rheological behavior and thermoreversibility of PNIPAM-co-TMA. Changes in solution moduli due to the thermal transitions and silane coupling are investigated via shear rheology. Even small incorporations (~5% mol) of co-solvents can lead to earlier onset of thermal transitions and large decreases in moduli upon macrophase separation. At elevated temperatures, systems with co-solvent display lower moduli than purely aqueous systems; however, once cooled below the transition temperature larger increases in moduli are observed in co-solvent systems compared to aqueous systems. These results suggest that co-solvent systems may lead to increased intermolecular crosslinking while also reducing moduli which may be advantageous for high shear rate processing including spraying and printing.