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Shanzuo Ji's Dissertation.pdf (3.57 MB)

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BIO-INSPIRED POLYMER LENS SYSTEMS FROM MULTILAYERED FILMS

Ji, Shanzuo
http://orcid.org/0000-0002-8680-1348
http://rave.ohiolink.edu/etdc/view?acc_num=case1441292644

Abstract Details

2016, Doctor of Philosophy, Case Western Reserve University, Macromolecular Science and Engineering.
CHAPTER1: A synthetic polymeric lens was designed and fabricated based on a bio-inspired, “Age=5” human eye lens design by utilizing a nanolayered polymer film-based technique. The internal refractive index distribution of an anterior and posterior GRIN lens were characterized and confirmed against design by µATR-FTIR. 3D surface topography of the fabricated aspheric anterior and posterior lenses was measured by placido-cone topography and exhibited confirmation of the desired aspheric surface shape. Furthermore, the wavefronts of aspheric posterior GRIN and PMMA lenses were measured and simulated by interferometry and Zemax software, respectively. Their results show that the gradient index distribution reduces the overall wavefront error as compared a homogenous PMMA lens of an identical geometry. Finally, the anterior and posterior GRIN lenses were assembled into a bio-inspired GRIN human eye lens through which a clear imaging was possible. CHAPTER 2: A nanolayered polymer films approach to designing and fabricating gradient refractive index lens (GRIN) lenses with designer refractive index distribution profiles and an independently prescribed lens surface geometry has been demonstrated to produce a new class of gradient index optics. This approach utilized nanolayered polymer composite materials from polymethylmethacrylate (PMMA) and a styrene-co-acrylonitrile copolymer (SAN) with a tailorable refractive index intermediate to bulk materials to fabricate discrete gradient refractive index profile materials. A process to fabricate nanolayered polymer GRIN optics from these materials through thermoforming and finishing steps is also described. A review of a collection of technology-demonstrating nanolayered GRIN case studies is which include: optical performance of an f/# 2.25 spherical GRIN plano-convex singlet 1/10 the weight of a similar BK7 lens and a bio-inspired aspheric human eye lens. Original research on the fabrication and characterization of a Luneburg inspired GRIN ball lens is presented as a developing application of the nanolayered polymer technology. CHAPTER 3: Compact and adaptive-focus tunable lenses have drawn increasing attention in the field of imaging applications including cellphone cameras, video endoscopes, and optical fiber components. This study demonstrated an all-solid-state thermoplastic elastomer tunable lens where the focal length was altered by the lens radius variation under a compressive pressure. The elastic behavior of the lens material was also investigated in the hysteresis study, which indicated that the conditioned lens material possessed a better elastomeric properties after the first cycle of loading and unloading. The radius of curvature of the tunable lens was simultaneously measured by a corneal topographer during compression. The results showed at a 0.4 mm compression, the lens curvature decreased from 12.86 mm down to 10.41 mm, which resulted in 19% of focal length change in the tunable lens. An ANSYS finite element analysis (FEA) model was used to predict shape deformation of the tunable lens during compression, which correlated well with the experimental results. CHAPTER 4: Triple shape memory polymers are capable of memorizing two temporary shapes and sequentially recovering from the first temporary shape to the second temporary shape, and eventually to the permanent shape upon exposure to heat. In this paper, unique three component multilayered films with ATBTATBTA configuration were produced by using a forced assembly multilayer film coextrusion process for a novel triple shape memory system. The films consisted of 65 polyurethane (PU) layers and 64 ethylene vinyl acetate (EVA) layers and separated by 128 poly(vinyl acetate) (PVAc) layers. The resulting films have two well separated thermal transition temperatures, one from the melting temperature of EVA and the other from the glass transition temperature of PVAc, which were used to subsequently fix two temporary shapes. The cyclic thermo-mechanical testing results showed that 257-layered PU/EVA/PVAc films possessed outstanding triple shape memory performance in term of shape fixity and shape recovery ratios. This approach allows greater design flexibility to some specific applications that are in need of simultaneous adjustment of the mechanical and shape memory properties.
Eric Baer, Prof. (Committee Chair)
Alexander Jamieson , Prof. (Committee Member)
Andrew Olah, Dr. (Committee Member)
Donald Schuele, Prof. (Committee Member)
145 p.
Polymers
Bi-oinspired Gradient Refractive Index Lens; Triple Shape Memory Polymer Films; Multilayer Film Co-extrusion; and Structure-Properties-Relationships

Recommended Citations

Citations

  • Ji, S. (2016). BIO-INSPIRED POLYMER LENS SYSTEMS FROM MULTILAYERED FILMS [Doctoral dissertation, Case Western Reserve University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=case1441292644

    APA Style (7th edition)

  • Ji, Shanzuo. BIO-INSPIRED POLYMER LENS SYSTEMS FROM MULTILAYERED FILMS. 2016. Case Western Reserve University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=case1441292644.

    MLA Style (8th edition)

  • Ji, Shanzuo. "BIO-INSPIRED POLYMER LENS SYSTEMS FROM MULTILAYERED FILMS." Doctoral dissertation, Case Western Reserve University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=case1441292644

    Chicago Manual of Style (17th edition)

case1441292644
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This open access ETD is published by Case Western Reserve University School of Graduate Studies and OhioLINK.