Poly(vinyl alcohol) (PV A) is a polymer with unique properties such as biodegradablility, biocompatibility, non-toxicity and strong hydrogen bonding capability. These positive properties are due to the pendant hydroxyl groups which dominate the chemistry of the polymer but they can also lead to one major disadvantage, the polymer in water will show aging. The aging or syneresis is due to the polymer chains coming together to form crystalline regions and forcing the weakly bonded water molecules between the chains out. This effect can be countered upon the addition of solvents that interact with the polymer chains more strongly which helps to maintain the polymer network in a more amorphous state. Therefore the effect of solvents was investigated in various poly(vinyl alcohol) network states, from solution to gel and film. The solvents could be divided based on their ability to donate labile hydrogen atoms, protic or aprotic, or on their relative size. The protic solvents were propylene glycol (pG) and dipropylene glycol (DPG) and the aprotic were dimethyl sulphoxide (DMSO), 2-pyrrolidone, N-methyl pyrrolidone (NMP), and N-ethyl pyrrolidone (NEP). This knowledge was applied when methods, such as the addition of small cross-linkers and polymeric blends, were used to engineer the properties of PV A gels and films. The size of the additive and the solvent system it was in manufactured in played an important role in the outcome of the network. Two dicarboxylic acid cross-linkers were studied, glutaric acid and sebacic acid as well as ionic polymers with carboxylic acid functionalities were also investigated. The polyelectrolytes were poly( acrylic acid-eo-maleic acid) (P AM) and poly(2-acrylamido-2-methylpropanesulfonic acid) (P AMPS).
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:557855 |
| Date | January 2012 |
| Creators | Wright, E. J. |
| Publisher | Queen's University Belfast |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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