Date of Last Revision

2023-05-03 12:50:10


Chemical Engineering - Cooperative Education

Degree Name

Bachelor of Science

Date of Expected Graduation

Spring 2019


It was hypothesized that through the use of Hofmeister Ions, the lower critical solution temperature (LCST) of poly(vinyl methyl ether) (PVME) and poly(ethylene glycol)- poly(N-isopropylacrylamide) (PEG-b-pNIPAAm) block-copolymer could be controlled. Through literature searches and small lab experiments, our team found that there may be a connection between Hofmeister effects and phase transition of a thermo-responsive polymer. To try and prove this, the lab team decided to take four cations (Mg2+,Na+, Cs+, K+) in solution with the thermo-responsive polymers and compared their LCST to solutions of the thermo-responsive polymer in de-ionized (DI) water. From this study, it was found that the addition of ions in solution lowered the LCST of PVME from 32°C to 26°C-30°C (depending on the ion added) and the LCST of PEG-pNIPAAm from 31°C to 26°C -29°C (depending on the ion added). The implications of this study could aid in efforts to manufacture better drug delivery devices, cell scaffolds, and tissue growth mediums. With increased control on the temperature at which a polymer undergoes a phase transition, the more effective these products can be in practice. The work will be continued by the next group of students.

Research Sponsor

Bi-min Newby Zhang

First Reader

Jie Zheng

Second Reader

Edward Evans



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