All ETDs from UAB

Advisory Committee Chair

Eugenia Kharlampieva

Advisory Committee Members

Wayne J Brouillette

Gary M Gray

Shane A Catledge

Derrick R Dean

Document Type

Dissertation

Date of Award

2014

Degree Name by School

Doctor of Philosophy (PhD) College of Arts and Sciences

Abstract

Poly(N-vinylcaprolactam) (PVCL) is a temperature-responsive polymer displaying a low critical solution temperature (LCST) around 30 to 40℃ in aqueous solutions that is close to the human physiological temperature. In addition, compared to other ther-moresponsive polymers, PVCL is nontoxic and biocompatible. In this thesis, we will fo-cus on the synthesis, fabrication and characterization of PVCL-based thermoresponsive nanostructured materials, such as films, hydrogels and block copolymers and their poten-tial applications in biomedical and medical areas. In chapter 2, we report on nanothin multilayer hydrogels of cross-linked PVCL that exhibited distinctive and reversible thermoresponsive behavior. The single-component PVCL hydrogels were produced by selective cross-linking of PVCL in layer-by-layer films of PVCL-NH2 copolymers assembled with poly(methacrylic acid) (PMAA) via hy-drogen bonding. Temperature responsive PVCL capsules of cubical and spherical shapes were fabricated through layer-by-layer deposition on inorganic templates. In order to precisely adjust the hydrophilicity and temperature responsive property of PVCL hydrogels, poly (N-vinyl-2-pyrrolidone) (PVPON) and PVCL hybrid film hy-drogels were constructed and systematically investigated in chapter 3. Our work opened new prospects for the development of biocompatible and nanothin hydrogel-based coat-ings and containers for temperate-regulating drug delivery, cellular uptake, sensing, and transportation behavior in microfluidic devices. In addition to PVCL based film hydrogels, we have also designed and synthesized PVCL based block copolymers in chapter 4. PVCL based block copolymers capable of self-assembling into various nanoscale structures that are attractive candidates in sensing, controlled delivery and as nanoreactors. The temperature-responsive PVCL-b-PVPON block copolymers were successfully synthesized by RAFT polymerization, and their as-sembly into temperature-sensitive nanostructures in aqueous solutions was investigated. The copolymers, soluble at room temperature, became amphiphilic as the solution tem-perature increased because of the reversible coil-to-globule transition of PVCL blocks. Remarkably, the PVCL-b-PVPON copolymers underwent temperature-induced self-assembly into nanostructures of 70 nm to 200 nm in size with hydrophobic PVCL blocks shielded by hydrophilic PVPON. In chapter 5, we designed and synthesized a novel VCL-based monomer, 3-methyl-N-vinylcaprolactam (MVC), to better control the LCST of the PVCL-based block copol-ymers. This new monomer together with VPON was employed to precisely tune up and down the LCST of PVCL copolymers over a wide range of temperatures through the controlled statistical radical copolymerization. Then, a series of P(VCL-stat-MVC)-b-P(VPON-stat-VCL) block copolymers with variable compositions and block ratios were prepared. Doubly temperature responsive diblock copolymers with two precisely tunable LCSTs were synthesized. Upon gradual heating of the block copolymers in aqueous solu-tion, a transition from free chains to micelles at low temperature and the collapse of the micelle corona around body temperature was observed.

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