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THE DESIGN OF A MULTIFUNCTIONAL INITIATOR-FREE SOFT POLYESTER PLATFORM FOR ROOM-TEMPERATURE EXTRUSION-BASED 3D PRINTING, AND ANALYSIS OF PRINTABILITY

Govindarajan, Sudhanva Raj
http://rave.ohiolink.edu/etdc/view?acc_num=akron1466778249

Abstract Details

2016, Doctor of Philosophy, University of Akron, Polymer Science.
A 3D printable functionalized polyester platform was developed using a coumarin pendant group as a photo-crosslinker. The coumarin pendant groups convert the copolyester from a viscous liquid to an elastomeric solid under 365 nm UV light at room temperature without the use of an initiator. Relatively hydrophobic variants of this platform (SC) was created using unsaturated aliphatic chains derived from soybean oil as pendant groups. A hydrogel variant (CPP) of this platform was created by using polyethylene glycol (PEG) as a backbone. Cell studies of the SC copolyester showed no toxic effects over short time scales. Rheological analysis demonstrated that all polymers over a range of molar feed ratios and molar masses were shear thinning. The SC platform has a very high entanglement molecular weight and has rheological behavior similar to that of an un-entangled brush. UV crosslinking of both SC and CPP platforms create thermosetting elastomeric solids. The relatively SC platform exhibits a high degree of fully reversible elastic deformation under shear due to chain extensibility and lack of trapped entanglements. Multiple pendant functional groups can be readily incorporated into this platform. Primary amine functionality was incorporated into the SC copolyester as a proof of concept. Extrusion based 3D printing (EBP) was successfully demonstrated on both platforms and FITC was successfully covalently clicked onto the primary amine functional group post-printing. Extrusion of the SC platform was accelerated due to UV extrusion. This might be due to Rouse-like behavior under shear coupled with excitation of cis double bonds in the unsaturated pendant groups. Examination of defects accumulated during the 3D printing process demonstrated that dynamic viscoelasticity due to print speed V affected the overall quality of the print. Interfacial chain relaxation institutes a lag-time between initial deposition and adhesion which increases with V. Deformability of the polymer substrate due to shear during deposition can negatively impact adhesion during this lag time, forming a defect. This phenomenon was modeled using two comprehensive equations.
Abraham Joy, PhD (Advisor)
Ali Dhinojwala, PhD (Committee Chair)
Mesfin Tsige, PhD (Committee Member)
Coleen Pugh, PhD (Committee Member)
Jae-Won Choi, PhD (Committee Member)
226 p.
Engineering; Materials Science; Physics; Polymer Chemistry; Polymers
3D Printing; Biomaterials; Polyesters; Patterning; Polymers; Extrusion; Extrusion Based Printing; Unentangled Melts; Rouse Regime; Extrusion; Rheology of Inks; 3D Printing Rheology; Printability

Recommended Citations

Citations

  • Govindarajan, S. R. (2016). THE DESIGN OF A MULTIFUNCTIONAL INITIATOR-FREE SOFT POLYESTER PLATFORM FOR ROOM-TEMPERATURE EXTRUSION-BASED 3D PRINTING, AND ANALYSIS OF PRINTABILITY [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1466778249

    APA Style (7th edition)

  • Govindarajan, Sudhanva. THE DESIGN OF A MULTIFUNCTIONAL INITIATOR-FREE SOFT POLYESTER PLATFORM FOR ROOM-TEMPERATURE EXTRUSION-BASED 3D PRINTING, AND ANALYSIS OF PRINTABILITY . 2016. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1466778249.

    MLA Style (8th edition)

  • Govindarajan, Sudhanva. "THE DESIGN OF A MULTIFUNCTIONAL INITIATOR-FREE SOFT POLYESTER PLATFORM FOR ROOM-TEMPERATURE EXTRUSION-BASED 3D PRINTING, AND ANALYSIS OF PRINTABILITY ." Doctoral dissertation, University of Akron, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1466778249

    Chicago Manual of Style (17th edition)

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This open access ETD is published by University of Akron and OhioLINK.