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The Precourt Institute for Energy is part of the Stanford Doerr School of Sustainability.

A Circular 3D-Printing Economy Enabled by Photon Upconversion

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Precourt Pioneering Project

Awarded in the focus area of re-inventing plastics and their lifecycle of use.
Award start date: October 1st, 2021.


Graphic of 3d printing technology

The 3D-printing market is growing at a dizzying pace, and it is predicted that over 10% of all manufactured products will be 3D printed within 10 years. Approximately 30% of bulk 3D-printed material is immediately discarded after fabrication, as most 3D prints require support structures to realize complex form factors. Currently, leftover plastic from 3D printing can only be recycled using expensive, specialized equipment for melting and extrusion. These recycling processes do not regenerate the original resin, and “new” prints generated from recycled resins typically exhibit inferior mechanical properties.

Project Goal

The overarching goal of this research is to reduce plastic waste from three-dimensional (3D) printing processes by developing a reusable 3D printing resin that can be printed, bulk erased, and re-printed over numerous cycles. This technology will be enabled by utilizing ‘print’ and ‘erase’ chemistry triggered by distinct wavelengths of light and will take advantage of upconverting nanocapsules to utilize low-energy photons to excite these processes. This will simplify the 3D-printing process by allowing deep light penetration into a sample and will reduce the materials costs of this technology.

Tasks and Timeline

The team will generate prints from recycled resin that have comparable physical properties to those of prints from fresh resin. This goal will be accomplished through three specific aims:
• Design and characterize fresh and recycled 3D-printing resins,
• Improve the quality and durability of the upconverting nanocapsules
• Engineer an integrated photochemical system that enables a circular 3D-printing economy.


1. Q. Zhou, B. M. Wirtz, T. H. Schloemer, M. C. Burroughs, M. Hu, P. Narayanan, J. Lyu, A. O. Gallegos, D. J. Mai, D. N. Congreve. 2022. “UV-emitting aqueous micelles facilitated by triplet-triplet annihilation upconversion." ACS Polym. Au., 3, 2, 217–227.

2. M. C. Burroughs, T. H. Schloemer, D. N. Congreve, D. J. Mai. 2023. “Gelation dynamics during photocrosslinking of polymer nanocomposite hydrogels”, ACS Polym. Au., 3, 2, 217–227. 

Team Members

Dan Congreve

Dan Congreve
Dan Congreve is an Assistant Professor in the Department of Electrical Engineering at Stanford University. Prior to Stanford, Dan was a Rowland Fellow at the Rowland Institute at Harvard University. His research focuses on engineering nanomaterials and optoelectronic devices to solve challenging problems in photovoltaics, light emission, and 3D printing.

Yan Xia

Yan Xia
Yan Xia is an Associate Professor of Chemistry at Stanford University. His research combines catalysis, organic and polymer chemistry, and a range of advanced characterizations to create, control, and study novel (macro)molecular structures and organic materials with tailored conformations, nanostructures, properties, and functions. 

Danielle Mai

Danielle J. Mai
Danielle Mai is an Assistant Professor of Chemical Engineering at Stanford University. Danielle’s research aims to engineer functional biomaterials and to enhance the fundamental understanding of soft matter physics.


Tracy Schloemer

Tracy Schloemer
Tracy H. Schloemer is a postdoctoral scholar in the Department of Electrical Engineering at Stanford University under Prof. Dan Congreve. Her current research focuses on the control and application of triplet fusion upconversion in complex soft matter-based systems.

Michael Burroughs

Mike Burroughs
Mike Burroughs is a Postdoctoral Scholar in the Department of Chemical Engineering at Stanford University. His research interests include the molecular design of polymers to engineer sustainable soft materials. During his Ph.D. at UC Santa Barbara, he focused on understanding flow instabilities and the nonlinear rheology of entangled polymer liquids.

Qi Zhou

Qi Zhou
Qi Zhou received her Honors B.S. degree in Materials and Nanoscience from Beijing Jiaotong University and University of Waterloo, where she gained research experience on moisture-induced nanogenerators (under Prof. Norman Zhou) and ultrastable polymeric glasses (under Prof. James Forrest).