Advisor(s)
Eugenia Kharlampieva
Committee Member(s)
Wayne J Brouillette
Aaron S Catledge
Ashish K Pathak
Sadanandan E Velu
Document Type
Dissertation
Date of Award
2013
Abstract
The research presented in this thesis is focused at the design and fabrication of pH-responsive layer-by-layer (LbL) hydrogels and the synthesis of the ABA block copolymer poly(2-methyloxazoline)-block-poly(dimethylsiloxane)-block-poly(2-methyl-oxazoline) (PMOXA-b-PDMS-b-PMOXA). Ultrathin stimuli-responsive layer-by-layer hydrogels, as compared to bulk hydrogels, can respond to external stimuli in a short time range (usually within seconds) which renders them particularly useful in sensing. Moreover, layer-by-layer technique allows the hydrogel film to be deposited with controlled thickness growth. However, the fabrication of LbL hydrogels with controllable cross-linking density and swelling degree still remains challenging. In chapter two, novel pH-sensitive LbL hydrogels based on poly(4-vinyl pyridine) (P4VP) were fabricated. Amino-containing units with appropriate molar ratio were incor-porated into the P4VP during polymerization to provide the copolymers with certain amount of cross-linking sites; thus, it was possible to fabricate P4VP LbL hydrogels with controllable cross-linking density. In chapter three, the pH-triggered swelling behavior and surface wettability of P4VP hydrogels were examined. The (P4VP-NH2-4) multilayer hydrogel, containing 4% amino-bearing units, exhibited 10-fold swelling at pH=2 and a sharp transition from hydrophilic to hydrophobic state when pH changed from 2 to 6. In contrast, the (P4VP-NH2-7) hydrogel film displayed merely a 4-fold swelling at pH=2. In chapter four, novel polyacid LbL hydrogels were synthesized and their pH-triggered swelling was investigated. Poly(acrylic acid) (PAA) and poly(meth- acrylic acid) (PMAA) have been applied in biomedical research due to their biocompatibility. PAA or PMAA copolymer incorporated amino groups were able to cross-link either by the for-mation of amide bonds or by selectively reacting with amino groups with cross-linking reagent. PMAA LbL hydrogel cross-linked among amino groups presented higher swell-ing degree. Further, spin-assisted assembled multilayer hydrogels displayed higher swell-ing than dipped hydrogels. In chapter five, a synthetic protocol for ABA-type block copolymer PMOXA-b-PDMS-b-PMOXA was established. This copolymer could assemble into nano-sized pol-ymersomes for advanced applications in therapeutics and diagnostics. However, the syn-thesis of this copolymer has not been thoroughly discussed in the previous studies. The modified procedure allowed us to build up a library of this copolymer with variable hy-drophilic to hydrophobic ratios.
ProQuest Publication Number
ISBN
978-1-303-32369-0
Recommended Citation
Wang, Yun, "Synthesis of pH-Responsive Multilayer Hydrogels and Amphiphilic Block Copolymers" (2013). All ETDs from UAB. 3255.
https://digitalcommons.library.uab.edu/etd-collection/3255
Comments
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