Rapid High-Resolution Visible Light 3D Printing

Abstract

Light-driven 3D printing to convert liquid resins into solid objects (i.e., photocuring) has traditionally been dominated by engineering disciplines, yielding the fastest build speeds and highest resolution of any additive manufacturing process. However, the reliance on high-energy UV/violet light limits the materials scope due to degradation and attenuation (e.g., absorption and/or scattering). Chemical innovation to shift the spectrum into more mild and tunable visible wavelengths promises to improve compatibility and expand the repertoire of accessible objects, including those containing biological compounds, nanocomposites, and multimaterial structures. Photochemistry at these longer wavelengths currently suffers from slow reaction times precluding its utility. Herein, novel panchromatic photopolymer resins were developed and applied for the first time to realize rapid high-resolution visible light 3D printing. The combination of electron-deficient and electron-rich coinitiators was critical to overcoming the speed-limited photocuring with visible light. Furthermore, azo-dyes were identified as vital resin components to confine curing to irradiation zones, improving spatial resolution. A unique screening method was used to streamline optimization (e.g., exposure time and azo-dye loading) and correlate resin composition to resolution, cure rate, and mechanical performance. Ultimately, a versatile and general visible-light-based printing method was shown to afford (1) stiff and soft objects with feature sizes <100 μm, (2) build speeds up to 45 mm/h, and (3) mechanical isotropy, rivaling modern UV-based 3D printing technology and providing a foundation from which bio- and composite-printing can emerge.

Rapid High‐Resolution 3D Printing and Surface Functionalization via Type I Photoinitiated RAFT Polymerization

“…Overcuring of 3D printable resins is commonly observed in UV and violet light curing DLP printing. This can be reduced by using a light absorbing dye, which prevents light scattering and improves print resolution in all axes [11, 33] . The addition of BTPA appears to similarly confine curing to irradiation zones and improves the resolution of printed samples.…”

“…This can be reduced by using a light absorbing dye, which prevents light scattering and improves print resolution in all axes. [11,33] The addition of BTPA appears to similarly confine curing to irradiation zones and improves the resolution of printed samples. These results were reproducible using 0.…”

On the Use of Surfactant‐Complexed Chitosan for Toughening 3D Printed Polymethacrylate Composites

“…Additive manufacturing (AM), commonly referred to as 3D printing, allows fabrication of polymers, ceramics, and metals with high levels of complexity and precision that cannot be achieved by traditional subtractive manufacturing routes. [ 1–5 ] The advent of 3D printing gives rise to improved material properties and even introduces new features and functions to the current technology, such as rapid, high resolution printing for smooth free‐form solids, micro‐optics, and robotics; [ 1,6 ] multi‐material printing for diverse and complex 3D hierarchical functional systems such as wearable electronics and solid‐state lightings; [ 7,8 ] and spatially controlled printing for fabrication of stimuli responsive materials tailored toward bioprinting. [ 9,10 ] Recently, 3D printing has been a key player in helping the current emergency situations with COVID‐19 pandemic.…”

Preparation of graphene oxide liquid crystals with long-range highly-ordered flakes using a coat-hanger die

“…† To verify the simulation results, it is necessary to prepare the coat hanger to die with high precision. A photo-curing 3D printer, which uses micron-level patterned UV light to cure the photosensitive resin was used to prepare 5 different coat-hanger dies 29,30 for the different concentrations of GO dispersions with only slightly modied dimensions of the dies (see ESI †). The preparation progress of the coat-hanger die is shown in Fig.…”