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Production of Poly(lactic acid) Biodegradable Films and the Introduction of a Novel Initiation Method for Free Radical Polymerization via Magnetic Fields

Miller, Kent R.

Abstract Details

2012, Doctor of Philosophy, University of Akron, Polymer Engineering.

Biocompatible and biodegradable polymeric systems benefit the biomedical field in applications such as tissue engineering, drug delivery, and implantable devises. In order for these applications to experience wide spread use, rapid and efficient production of these materials with controllable mechanical and degradative properties needs to be possible. Furthermore, the biomaterials should be easily incorporated into the body with minimal damage. In the first part of this study, telechelic acrylic poly(lactic acid) (PLA) oligomers were prepared through transesterification of PLA with ethylene glycol diacrylate. The oligomers were then incorporated into a series of photopolymerizable, biodegradable, and biocompatible films. The second part of this study introduces a new initiation method, magnetic initiation, which will allow polymeric systems to be polymerized without the use of heat or application or radiation. In magnetic initiation, free radicals will be produced by means of a magnetic macro-initiator (MI) and an alternating current magnetic field (AC MF).

PLA films were formulated to contain either 1,4-Butanediol dimethacrylate (BDDM) or triethylene glycol dimethacrylate (TEGDMA). The kinetics of the photopolymerizable material was studied by photo-differential scanning calorimeter (DSC). Additionally, the tensile properties, pencil hardness, reverse impact resistance, pull of adhesion, and solvent resistance of the coatings were evaluated. Degradation was monitored by direct measurement of the carboxylic acid groups formed upon ester hydrolysis of the films in an enzyme solution by means of titration. Photo-DSC results showed that the photo-curing speed of the samples decreased as the concentration of PLA increased. Both water uptake and degradation rate increased as the concentration of PLA increased and were higher for films formulated with TEGDMA, for a given PLA concentration. The degradation rate of the films was proportional to the water uptake of the film and the degradative enzyme solution used. Higher PLA concentration also resulted in films that were softer and more flexible.

Magnetic MIs were synthesized by grafting a molecule containing a decomposable weak link onto the surface of a silica coated magnetic nanoparticle (Fe3O4, FeCo, or Co). To determine the energy required to decompose the magnetic MIs, a molecular dynamic simulation was performed. The ability of the magnetic MIs to initiator free radical polymerization was then investigated by means of a calorimetric and a kinetic study on the polymerization of different acrylic systems (urethane, epoxy, and a biocompatible polyphosphazene system). From the molecular dynamic simulation, it was determined that the dissociation energy of the magnetic MIs is 34.5 kcal/mol. The calorimetric and kinetic studies showed that the magnetic MIs are capable of decomposing into free radicals and initiating polymerization when exposed to an AC MF.

Mark Soucek, Dr. (Advisor)
Thein Kyu, Dr. (Committee Member)
Gustavo Carri, Dr. (Committee Member)
David Modarelli, Dr. (Committee Member)
Kevin Cavicchi, Dr. (Committee Chair)
185 p.

Recommended Citations

Citations

  • Miller, K. R. (2012). Production of Poly(lactic acid) Biodegradable Films and the Introduction of a Novel Initiation Method for Free Radical Polymerization via Magnetic Fields [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1341862599

    APA Style (7th edition)

  • Miller, Kent. Production of Poly(lactic acid) Biodegradable Films and the Introduction of a Novel Initiation Method for Free Radical Polymerization via Magnetic Fields. 2012. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1341862599.

    MLA Style (8th edition)

  • Miller, Kent. "Production of Poly(lactic acid) Biodegradable Films and the Introduction of a Novel Initiation Method for Free Radical Polymerization via Magnetic Fields." Doctoral dissertation, University of Akron, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=akron1341862599

    Chicago Manual of Style (17th edition)