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3D in situ Chemical Synthesis: Additive Manufacturing of Functional Polymeric Materials via Vat Photo-polymerization


Chen, Amylynn C. (2023) 3D in situ Chemical Synthesis: Additive Manufacturing of Functional Polymeric Materials via Vat Photo-polymerization. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/ca3e-rc06.


As additively manufacturing gains popularity in rapid-prototyping, manufacturing and customized production, there is a continuous demand in seeking for new materials with advanced functionalities to satisfy the wide range of applications in aerospace, construction, optics, actuation, dentistry, biomedical practices and even food industry. Vat photopolymerization (VP), a light-enabled AM technique, is particularly promising due to its ability to achieve good surface quality, high resolution, and large volumetric throughput. The vast majority of materials obtained by VP are covalently-crosslinked thermosets with nondegradable carbon backbones. This highly crosslinked molecular structure gives rise to stiff and brittle materials, limiting the structural functionality in desired applications.

This thesis explores a variety of molecular structures for new VP photopolymers: a) dynamically-crosslinked compliant polymer, b) interpenetrating network (IPN) hydrogel, and c) covalently-crosslinked polymer with labile group (ex. ester) insertion to polymer backbone. With the dynamic crosslinking system, we demonstrate tunable mechanical behaviors of the metal-coordinated supramolecular polymers. These materials display a range of failure strain of 450% - 940% and ultimate tensile strength of 12.4 - 2.2 MPa with varying resin compositions. To incorporate multifunctionality, we design thermoresponsive IPN hydrogels by fabricating a hydrophilic host polymer network via VP and a subsequent formation a thermoresponsive 2nd network (poly(N-Isopropylacrylamide)). The architected IPNs consistently display strong polymer-liquid phase separation behavior and a tunable water release behavior with volumetric shrinkage between 30% and 70% upon heating at 50oC. Finally, to promote the degradability of the acylate-based photoresin, we demonstrated successful incorporation for ester functional groups into the polymer backbone via radical ring opening polymerization of cyclic ketene acetals. The obtained polymer undergoes 84% mass loss within 7 hours under hydrolytic degradation condition. Overall, we demonstrated VP as a powerful technique to achieve one-pot synthesis and fabrication of functional materials. Our explorations on the development of degradable photopolymers, thermoresponsive double-network hydrogels, and metal-coordinated supramolecular polymers provide valuable insights into the impact of resin formulation on mechanical properties. From analyzing the molecular weight of 3DP materials to finetuning of phase separation behavior and degradability, we demonstrate that VP provides a new platform to inspire advanced photoresin design strategies for desirable mechanical performance.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Additive manufacturing, 3D printing
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Materials Science
Awards:ACS Spring 2021 - "Excellence in Graduate Polymer Research”
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Greer, Julia R.
Thesis Committee:
  • Gao, Wei (chair)
  • Faber, Katherine T.
  • Wang, Zhen-Gang
  • Greer, Julia R.
Defense Date:14 July 2022
Funding AgencyGrant Number
Defense Advanced Research Projects Agency (DARPA)F1962889K0028
Record Number:CaltechTHESIS:06022023-145117270
Persistent URL:
Chen, Amylynn C.0000-0002-8112-5862
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:16057
Deposited By: Amylynn Chen
Deposited On:06 Jun 2023 17:56
Last Modified:08 Nov 2023 00:27

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