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Swelling and Contraction Properties for Polyelectrolytes Multilayers and Polymer Thin Films Measured by In-situ Ellipsometry

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2016, Master of Science, University of Akron, Polymer Engineering.
Weak polyelectrolyte multilayers (PEMs) fabricated by the Layer by Layer (LBL) assembling technique showed special swollen and contraction behaviors when they came in contact with water and organic liquids. The contraction responses of PEM were found to be dependent on the solvent selection. The correlation between the degrees of the films contraction and the solvent type needed be explored. Therefore, in this study, we utilized solubility parameters to discuss the responses for branched poly (ethylene imine)/poly (acrylic acid) (BPEI/PAA) multilayers when soaked in a variety of solvent liquids. When immersed in organic solvents, film dehydrated and contraction also caused mechanical property changes for BPEI/PAA films. The film’s thickness was the best predictor for determining how a film swelled in water or contracted in organic liquid. The hydrogen bonding ability of the solvents played an important role in determining the degree of film contraction in most cases, for these solvents, it did so when increasing the temperature of the measurement corresponding to reducing the strength of the hydrogen bonding, and decreasing the ability to dehydrate the films as well. However, some solvents did not follow the linear trend with the strength of hydrogen bonding; in these, a stronger correlation was observed between contraction degrees and dielectric constants, showing that traditional solvent quality discussions and electrostatics were significant to understanding the contraction behavior of PEMs in organic solvents. Besides the PEM system, the swelling behavior of poly(n-propyl methacrylate), PPMA, films in water were also measured in-situ using spectroscopic ellipsometry. Two different end groups grafted poly (n-propyl methacrylate)s with similar high molecular weight were successfully synthesized by the reversible addition-fragmentation chain-transfer polymerization (RAFT) synthesis method. The end group of the two PPMAs impacted the swelling behavior over the temperature range of 25 to 50 ¿. At 25 ¿, the dithiobenzoate terminated PPMA (PPMA-DB) leading to significantly less swelling (4.2 vol%) than the dodecylsulfanylthiocarbonyl terminated PPMA (PPMA-DD, 6.4 vol%). These PPMA films swelled significantly more than one would expect since their hydrophobicity, which was attributed to the other end group from RAFT being a carboxylic acid in both polymers. As the temperature was increased, the swelling for the PPMA-DB increased; the swelling decreased for the PPMA-DD with a crossover at approximately 35 ¿. Both the swelling processes had two stages: an initial rapid swelling within the first minute and then a slow increase in thickness over several hours. The different swelling trends of the PPMA-DB and PPMA-DD described the end group effect on the polymers especially the chain conformations. Additionally, for the mechanical properties of these two kinds of PPMA, the elastic modulus was similar; however, the fracture modulus showed some difference, in that the larger swelling PPMA-DD films have a somewhat smaller fracture strength also influenced by the different end groups.
Nicole Zacharia, Dr. (Advisor)
Bryan Vogt, Dr. (Advisor)
Alamgir Karim, Dr. (Committee Chair)
89 p.

Recommended Citations

Citations

  • Ma, Y. (2016). Swelling and Contraction Properties for Polyelectrolytes Multilayers and Polymer Thin Films Measured by In-situ Ellipsometry [Master's thesis, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1468755937

    APA Style (7th edition)

  • Ma, Yubing. Swelling and Contraction Properties for Polyelectrolytes Multilayers and Polymer Thin Films Measured by In-situ Ellipsometry. 2016. University of Akron, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1468755937.

    MLA Style (8th edition)

  • Ma, Yubing. "Swelling and Contraction Properties for Polyelectrolytes Multilayers and Polymer Thin Films Measured by In-situ Ellipsometry." Master's thesis, University of Akron, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1468755937

    Chicago Manual of Style (17th edition)