Responsive polymers for dynamic modulation of bio-macromolecular transport properties

Responsive self-assembling polymers are used in wide range of applications in the food, pharmaceutical, agricultural, electronic and environmental industries, as well as in the biomedical field. The proper design of such polymers is critical for the particular applications being considered. In this thesis, different matrices that can be modulated dynamically by the application of appropriate stimuli were designed and used for two applications: electrophoretic separation and gene transfection. Light represents an attractive trigger to change the properties of a polymer solution because it enables structural transitions to be induced under isothermal conditions without the addition of other chemical species to the solution, and is externally reversible and hence amenable to device design and automation. Amphiphilic copolymers with azobenzene moieties are of interest because the azobenzene can undergo reversible trans-cis photoisomerization leading to conformational isomers with significantly dissimilar dipole moments and hydrophobicities and thus different propensities to aggregate into nanoscale structures in aqueous media. Copolymers of 4methacryloyloxyazobenzene (MOAB) and N,N-dimethylacrylamide aggregate strongly in aqueous solutions with concentration-dependent aggregate size distributions and welldefined boundaries between the dilute and semi-dilute regimes. The copolymers are strongly surface active, an uncommon observation for random copolymers, and exhibit pronounced photoviscosity effects at higher concentrations. Trans-to-cis isomerization under UV light leads to partial dissociation of the azobenzene aggregates that form physical crosslinks, thereby significantly affecting the polymer solution rheology, with a consequent ten-fold loss of viscoelasticity upon irradiation, especially in concentrated polymer solutions. Photo-responsive poly(N,N-dimethylacrylamide-co-methacryloyloxyazobenzene) (MOAB-DMA) and temperature-responsive Pluronic F127 (PF127) copolymers were blended to obtain mixed micellar systems that were responsive to both stimuli.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Chemical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2008

Author dc:creator

• Deshmukh, Smeet

Advisor dc:contributor.advisor

• T. Alan Hatton and Kenneth A. Smith.

• Chemical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/45926

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/45926