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FUNCTIONAL 4D PRINTING BY 3D PRINTING SHAPE MEMORY POLYMERS VIA MOLECULAR, MORPHOLOGICAL AND GEOMETRICAL DESIGNS

Peng, Bangan
http://orcid.org/0000-0003-1497-0617
http://rave.ohiolink.edu/etdc/view?acc_num=akron1605873309517501

Abstract Details

2020, Doctor of Philosophy, University of Akron, Polymer Science.
4D printing is an emerging technology that combines 3D printing and stimuli-responsive materials. The core idea of 4D printing is `3D printing +time', where the geometries, properties and functionalities of 3D printed structures can evolve as a function of time. While simple shape transformation has been achieved in most 4D printing systems, more limited attention has been paid to 4D printing with multi-functionality or complex shape transformation patterns. However, these properties are of critical importance for advanced applications. For example, sequential shapeshifting is useful for consecutive motion and actuation of soft robotics. High flexibility and extensibility are desired properties in soft electronics and some biomedical devices. To address these limitations, we developed functional 4D printing based on rational designs of shape memory polymers at molecular, morphological and geometrical levels. First, we achieved the first triple shape memory polymer by digital light processing (DLP) 3D printing. We prepared DLP printable resins containing an ion-pair comonomer and acrylates, and obtained ampholytic ionomers through photocuring. These ionomers featured microphases-separated morphology, which generated two glass transition temperatures (Tg) associated with the ion-rich and ion-poor domains. The well-separated Tgs produced excellent triple shape memory effect. The influences of neutral comonomers on microphase separation and Tgs were investigated systematically by dynamic mechanical analysis (DMA) and atomic force microscopy (AFM). Finally, sequential shapeshifting through different shape evolution pathways and its application in microfluidics were demonstrated. Second, we 4D printed a highly extensible, self-healing shape memory elastomer based on fused filament fabrication (FFF) 3D printing. The material was made of a thermoplastic elastomer, polystyrene-block-poly(ethylene-co-butylene)-block-polystyrene (SEBS), and a semi-crystalline thermoplastic, polycaprolactone (PCL). We demonstrated the excellent shape memory and self-healing properties, and conducted thermomechanical and morphological studies to establish the structure-property relationship of this material. In addition, the alignment of the crystalline domains and microphase-separated domains was found to greatly enhance the shape memory performances and the extensibility. The 3D printed materials have a high extensibility over 1200%, outperforming existing 4D printing flexible materials. The high performance, along with the low cost, of this 4D printing material makes it a promising candidate for a variety of applications. Third, a unique shape memory mechanism, architecture-induced shape memory effect (AISME), was realized through geometrical design of a 3D lattice structure. With the 3D architecture from 3D printing, the material exhibited shape programming by a single step of deformation at room temperature, which considerably enhanced the shape memory performances compared to conventional room temperature shape memory systems. More importantly, it provides a new strategy for developing smart materials. This special effect was not found in the base materials but arose from the 3D architectures, which means one can obtain and tune smart properties by designing the geometrical structures instead of chemical formulations. The mechanism was systematically analyzed and investigated from the point of view of polymer physics and structural mechanics. Finally, it was showcased that the structures with AISME possessed the ability in rapid, versatile and large amplitude shape-morphing and huge potentials in soft robotics and actuators.
Kevin Cavicchi (Advisor)
Li Jia (Committee Member)
Yu Zhu (Committee Member)
Weinan Xu (Committee Member)
Jae-Won Choi (Committee Member)
232 p.
Chemical Engineering; Mechanical Engineering; Polymers
3D printing; 4D printing; Shape memory polymer; Ionomer; SEBS; 3D architecture

Recommended Citations

Citations

  • Peng, B. (2020). FUNCTIONAL 4D PRINTING BY 3D PRINTING SHAPE MEMORY POLYMERS VIA MOLECULAR, MORPHOLOGICAL AND GEOMETRICAL DESIGNS [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1605873309517501

    APA Style (7th edition)

  • Peng, Bangan. FUNCTIONAL 4D PRINTING BY 3D PRINTING SHAPE MEMORY POLYMERS VIA MOLECULAR, MORPHOLOGICAL AND GEOMETRICAL DESIGNS. 2020. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1605873309517501.

    MLA Style (8th edition)

  • Peng, Bangan. "FUNCTIONAL 4D PRINTING BY 3D PRINTING SHAPE MEMORY POLYMERS VIA MOLECULAR, MORPHOLOGICAL AND GEOMETRICAL DESIGNS." Doctoral dissertation, University of Akron, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=akron1605873309517501

    Chicago Manual of Style (17th edition)

akron1605873309517501
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This open access ETD is published by University of Akron and OhioLINK.