The authors acknowledge funding from the Australian Research Council and UNSW Australia via the Discovery Research program (DP210100094).

1. Preparation of 3D printing program and 3D printer
<ol>
	<li>Design the digital model for 3D printing following the steps below.
	<ol>
		<li>Open a computer-assisted design program (see Table of Materials).</li>
		<li>In the x-y plane, create a rectangle centered on the origin having dimensions of 80 mm x 40 mm, then extrude along the positive z-axis for 1.5 mm to make a solid rectangular prism, called the base object.</li>
		<li>Above the base object, i.e., at z = 1.5 mm, draw the d...

<ol>
	<li>Ligon, S. C., Liska, R., Stampfl, J., Gurr, M., M&#252;lhaupt, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Polymers+for+3D+printing+and+customized+additive+manufacturing.">Polymers for 3D printing and customized additive manufacturing.</a> Chemical Reviews. 117 (15), 10212-10290 (2017).</li><li>Lewis, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+ink+writing+of+3D+functional+materials.">Direct ink writing of 3D functional materials.</a> Advanced Functional Materials. 16 (17), 2193-2204 (2006).</li><li>Kumar, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Selective+laser+sintering:+A+qualitative+and+objective+approach.">Selective laser sintering: A qualitative and objective approach.</a> JOM. 55 (10), 43-47 (2003).</li><li>Jung, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Designing+with+light:+Advanced+2D,+3D,+and+4D+materials.">Designing with light: Advanced 2D, 3D, and 4D materials.</a> Advanced Materials. 32 (18), 1903850 (2020).</li><li>Lim, K. S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fundamentals+and+applications+of+photo-cross-linking+in+bioprinting.">Fundamentals and applications of photo-cross-linking in bioprinting.</a> Chemical Reviews. 120 (19), 10662-10694 (2020).</li><li>Chen, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Photoinitiators+derived+from+natural+product+scaffolds:+Monochalcones+in+three-component+photoinitiating+systems+and+their+applications+in+3D+printing.">Photoinitiators derived from natural product scaffolds: Monochalcones in three-component photoinitiating systems and their applications in 3D printing.</a> Polymer Chemistry. 11 (28), 4647-4659 (2020).</li><li>Chen, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Novel+D-&#960;-A+and+A-&#960;-D-&#960;-A+three-component+photoinitiating+systems+based+on+carbazole/triphenylamino+based+chalcones+and+application+in+3D+and+4D+printing.">Novel D-&#960;-A and A-&#960;-D-&#960;-A three-component photoinitiating systems based on carbazole/triphenylamino based chalcones and application in 3D and 4D printing.</a> Polymer Chemistry. 11 (40), 6512-6528 (2020).</li><li>Zhang, J., Xiao, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=3D+printing+of+photopolymers.">3D printing of photopolymers.</a> Polymer Chemistry. 9 (13), 1530-1540 (2018).</li><li>Zhu, Y., Ramadani, E., Egap, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Thiol+ligand+capped+quantum+dot+as+an+efficient+and+oxygen+tolerance+photoinitiator+for+aqueous+phase+radical+polymerization+and+3D+printing+under+visible+light.">Thiol ligand capped quantum dot as an efficient and oxygen tolerance photoinitiator for aqueous phase radical polymerization and 3D printing under visible light.</a> Polymer Chemistry. 12 (35), 5106-5116 (2021).</li><li>Jiang, P., Ji, Z., Wang, X., Zhou, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface+functionalization+-+a+new+functional+dimension+added+to+3D+printing.">Surface functionalization - a new functional dimension added to 3D printing.</a> Journal of Materials Chemistry C. 8 (36), 12380-12411 (2020).</li><li>Gonzalez, G., Chiappone, A., Dietliker, K., Pirri, C. F., Roppolo, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fabrication+and+functionalization+of+3D+printed+polydimethylsiloxane-based+microfluidic+devices+obtained+through+digital+light+processing.">Fabrication and functionalization of 3D printed polydimethylsiloxane-based microfluidic devices obtained through digital light processing.</a> Advanced Materials Technologies. 5 (9), 2000374 (2020).</li><li>Yao, X., Song, Y., Jiang, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Applications+of+bio-inspired+special+wettable+surfaces.">Applications of bio-inspired special wettable surfaces.</a> Advanced Materials. 23 (6), 719-734 (2011).</li><li>Bose, S., Robertson, S. F., Bandyopadhyay, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface+modification+of+biomaterials+and+biomedical+devices+using+additive+manufacturing.">Surface modification of biomaterials and biomedical devices using additive manufacturing.</a> Acta Biomaterialia. 66, 6-22 (2018).</li><li>Wang, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=i3DP,+a+robust+3D+printing+approach+enabling+genetic+post-printing+surface+modification.">i3DP, a robust 3D printing approach enabling genetic post-printing surface modification.</a> Chemical Communications. 49 (86), 10064-10066 (2013).</li><li>Lee, K., Corrigan, N., Boyer, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+high-resolution+3D+printing+and+surface+functionalization+via+type+I+photoinitiated+raft+polymerization.">Rapid high-resolution 3D printing and surface functionalization via type I photoinitiated raft polymerization.</a> Angewandte Chemie International Edition. 60 (16), 8839-8850 (2021).</li><li>Zhang, Z., Corrigan, N., Bagheri, A., Jin, J., Boyer, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+versatile+3D+and+4D+printing+system+through+photocontrolled+raft+polymerization.">A versatile 3D and 4D printing system through photocontrolled raft polymerization.</a> Angewandte Chemie International Edition. 58 (50), 17954-17963 (2019).</li><li>Corrigan, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reversible-deactivation+radical+polymerization+(controlled/living+radical+polymerization):+From+discovery+to+materials+design+and+applications.">Reversible-deactivation radical polymerization (controlled/living radical polymerization): From discovery to materials design and applications.</a> Progress in Polymer Science. 111, 101311 (2020).</li><li>Moad, G., Rizzardo, E., Thang, S. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Living+radical+polymerization+by+the+raft+process+-+A+third+update.">Living radical polymerization by the raft process - A third update.</a> Australian Journal of Chemistry. 65 (8), 985-1076 (2012).</li><li>Chiefari, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Living+free-radical+polymerization+by+reversible+addition&#8722;Fragmentation+chain+transfer:+The+RAFT+process.">Living free-radical polymerization by reversible addition&#8722;Fragmentation chain transfer: The RAFT process.</a> Macromolecules. 31 (16), 5559-5562 (1998).</li><li>Fromel, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=User-friendly+chemical+patterning+with+digital+light+projection+polymer+brush+photolithography.">User-friendly chemical patterning with digital light projection polymer brush photolithography.</a> European Polymer Journal. 158, 110652 (2021).</li><li>Fromel, M., Li, M., Pester, C. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface+engineering+with+polymer+brush+photolithography.">Surface engineering with polymer brush photolithography.</a> Macromolecular Rapid Communications. 41 (18), 2000177 (2020).</li><li>Wang, C. -. G., Chen, C., Sakakibara, K., Tsujii, Y., Goto, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Facile+fabrication+of+concentrated+polymer+brushes+with+complex+patterning+by+photocontrolled+organocatalyzed+living+radical+polymerization.">Facile fabrication of concentrated polymer brushes with complex patterning by photocontrolled organocatalyzed living radical polymerization.</a> Angewandte Chemie International Edition. 57 (41), 13504-13508 (2018).</li><li>Zoppe, J. O., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surface-initiated+controlled+radical+polymerization:+state-of-the-art,+opportunities,+and+challenges+in+surface+and+interface+engineering+with+polymer+brushes.">Surface-initiated controlled radical polymerization: state-of-the-art, opportunities, and challenges in surface and interface engineering with polymer brushes.</a> Chemical Reviews. 117 (3), 1105 (2017).</li><li>Pester, C. W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ambiguous+antifouling+surfaces:+Facile+synthesis+by+light-mediated+radical+polymerization.">Ambiguous antifouling surfaces: Facile synthesis by light-mediated radical polymerization.</a> Journal of Polymer Science Part A: Polymer Chemistry. 54 (2), 253-262 (2016).</li><li>Poelma, J. E., Fors, B. P., Meyers, G. F., Kramer, J. W., Hawker, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fabrication+of+complex+three-dimensional+polymer+brush+nanostructures+through+light-mediated+living+radical+polymerization.">Fabrication of complex three-dimensional polymer brush nanostructures through light-mediated living radical polymerization.</a> Angewandte Chemie International Edition. 52 (27), 6844-6848 (2013).</li><li>Zhu, Y., Egap, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=PET-RAFT+polymerization+catalyzed+by+cadmium+selenide+quantum+dots+(QDs):+Grafting-from+QDs+photocatalysts+to+make+polymer+nanocomposites.">PET-RAFT polymerization catalyzed by cadmium selenide quantum dots (QDs): Grafting-from QDs photocatalysts to make polymer nanocomposites.</a> Polymer Chemistry. 11 (5), 1018-1024 (2020).</li><li>ASTM International. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=ASTM+Standard+D638-14:+Standard+Test+method+for+tensile+properties+of+plastics.">ASTM Standard D638-14: Standard Test method for tensile properties of plastics.</a> ASTM International. , (2014).</li><li>Moad, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=RAFT+(Reversible+addition-fragmentation+chain+transfer)+crosslinking+(co)polymerization+of+multi-olefinic+monomers+to+form+polymer+networks.">RAFT (Reversible addition-fragmentation chain transfer) crosslinking (co)polymerization of multi-olefinic monomers to form polymer networks.</a> Polymer International. 64 (1), 15-24 (2015).</li><li>Li, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=SI-PET-RAFT:+Surface-initiated+photoinduced+electron+transfer-reversible+addition-fragmentation+chain+transfer+polymerization.">SI-PET-RAFT: Surface-initiated photoinduced electron transfer-reversible addition-fragmentation chain transfer polymerization.</a> ACS Macro Letters. 8 (4), 374-380 (2019).</li></ol>

The authors declare no conflicts of interest.

The present protocol demonstrates a process for 3D printing of polymer materials with independently tunable bulk and interfacial properties. The procedure is performed via a two-step method by 3D printing the base substrate and subsequently modifying the surface layer of the 3D printed object using a different functional resin but using the same 3D printing hardware. While the 3D printers used in this work are designed to print crosslinked materials in a layer-by-layer fashion, the surface functionalization can ...

Additive manufacturing and 3D printing have revolutionized material manufacturing by providing more efficient and facile routes for the fabrication of geometrically complex materials1. Apart from the enhanced design freedoms in 3D printing, these technologies produce less waste than traditional subtractive manufacturing processes via the judicious use of precursor materials in a layer-by-layer manufacturing process. Since the 1980s, a wide range of different 3D printing techniques has been developed to fabricate polymeric, metal, and ceramic components1. The most commonly employed methods include extrusion-based 3D printing such as fused filament fabrication and direct ink writing techniques2, sintering techniques such as selective laser sintering3, as well as resin-based photoinduced 3D printing techniques such as laser and projection-based stereolithography and masked digital light processing techniques4. Among the many 3D printing techniques in existence today, photoinduced 3D printing techniques provide some advantages compared to other methods, including higher resolution and faster printing speeds, as well as the ability to perform solidification of the liquid resin at room temperature, which opens the possibility to advanced biomaterial 3D printing4,5,6,7,8,9.
While these advantages have allowed the widespread adoption of 3D printing in many fields, the limited ability to independently tailor the 3D printed material properties restricts future applications10. In particular, the inability to easily tailor the bulk mechanical properties independently of the interfacial properties limits applications such as implants, which require finely tailored biocompatible surfaces and often vastly differing bulk properties, as well as antifouling and antibacterial surfaces, sensor materials, and other smart materials11,12,13. Researchers have proposed surface modification of 3D printed materials to overcome these issues to provide more independently tailorable bulk and interfacial properties10,14,15.
Recently, our group developed a photoinduced 3D printing process that exploits reversible addition-fragmentation chain transfer (RAFT) polymerization to mediate network polymer synthesis15,16. RAFT polymerization is a type of reversible deactivation radical polymerization that provides a high degree of control over the polymerization process and allows for the production of macromolecular materials with finely tuned molecular weights and topologies, and broad chemical scope17,18,19. Notably, the thiocarbonylthio compounds, or RAFT agents, used during RAFT polymerization are retained after polymerization. They can thus be reactivated to modify further the chemical and physical properties of the macromolecular material. Thus, after 3D printing, these dormant RAFT agents on the surfaces of the 3D printed material can be reactivated in the presence of functional monomers to provide tailored material surfaces20,21,22,23,24,25,26. The secondary surface polymerization dictates the interfacial material properties and can be performed in a spatially controlled fashion via photochemical initiation.
The present protocol describes a method for 3D printing polymeric materials via a photoinduced RAFT polymerization process and the subsequent in situ surface modification to modulate the interfacial properties independently of the bulk material mechanical properties. Compared to previous 3D printing and surface modification approaches, the current protocol does not require deoxygenation or other stringent conditions and is thus highly accessible for non-specialists. Furthermore, the use of 3D printing hardware to perform both the initial material fabrication and the surface post-functionalization provides spatial control over the material properties and can be performed without the tedious alignment of several different photomasks to make complex patterns.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>1-pyrenemethyl methacrylate</td>
			<td>Sigma-Aldrich</td>
			<td>765120</td>
			<td></td>
		</tr>
		<tr>
			<td>2-(n-butylthiocarbonothioylthio) propanoic acid</td>
			<td>Boron Molecular</td>
			<td>BM1640</td>
			<td></td>
		</tr>
		<tr>
			<td>3D Printer</td>
			<td>Photon</td>
			<td>Mono S</td>
			<td>light intensity at digital mask surface = 0.81 mW cm-2</td>
		</tr>
		<tr>
			<td>3D Printing Slicing Software</td>
			<td>Photon</td>
			<td>Photon Workshop V2.1.19</td>
			<td></td>
		</tr>
		<tr>
			<td>40 kHz Ultrasonic Bath</td>
			<td>Thermoline</td>
			<td>UB-410</td>
			<td></td>
		</tr>
		<tr>
			<td>Compressed Air</td>
			<td>Coregas</td>
			<td>230142</td>
			<td>Tank operating at 130 kPa</td>
		</tr>
		<tr>
			<td>Computer Assisted Design Program</td>
			<td>SpaceClaim</td>
			<td>SpaceClaim Design Manager V19.1</td>
			<td></td>
		</tr>
		<tr>
			<td>Diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide</td>
			<td>Sigma-Aldrich</td>
			<td>415952</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol Undenatured 100% AR</td>
			<td>ChemSupply</td>
			<td>EL043-2.5L-P</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethanol Wash bottle</td>
			<td>Rowe Scientific</td>
			<td>AZLWGF541P</td>
			<td></td>
		</tr>
		<tr>
			<td>Fluorescence Imager</td>
			<td>Bio-Rad</td>
			<td>Gel Doc XR+</td>
			<td>Uses a 302 nm gas discharge lamp as emission source</td>
		</tr>
		<tr>
			<td>Light intensity power meter</td>
			<td>Newport</td>
			<td>843-R</td>
			<td></td>
		</tr>
		<tr>
			<td>Mechanical Tester</td>
			<td>Mark&#8211;10</td>
			<td>ESM303</td>
			<td>1 kN force gauge M5&#8211;200</td>
		</tr>
		<tr>
			<td>Moldable plastic film</td>
			<td>Parafilm</td>
			<td>PM992</td>
			<td></td>
		</tr>
		<tr>
			<td>N,N-dimethlacrylamide</td>
			<td>Sigma-Aldrich</td>
			<td>274135</td>
			<td></td>
		</tr>
		<tr>
			<td>N,N-Dimethylformamide HPLC</td>
			<td>ChemSupply</td>
			<td>LC1051-G4L</td>
			<td></td>
		</tr>
		<tr>
			<td>Poly(ethylene glycol) diacrylate average Mn 250</td>
			<td>Sigma-Aldrich</td>
			<td>475629</td>
			<td></td>
		</tr>
		<tr>
			<td>Post Cure Lamp</td>
			<td>Leoway</td>
			<td>&#8206;B0869BY79P</td>
			<td>60 W 405 nm</td>
		</tr>
		<tr>
			<td>Standards document</td>
			<td>ASTM</td>
			<td>ASTM Standard D638-14</td>
			<td></td>
		</tr>
		<tr>
			<td>Tensile testing machine</td>
			<td>Mark-10</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>UV Light</td>
			<td>Fisher Scientific</td>
			<td>11-982-30</td>
			<td>6 W Spectroline E-Series, Gas discharge lamp</td>
		</tr>
		<tr>
			<td>Vortex Mixer IKA Vortex 3</td>
			<td>LabTek</td>
			<td>3340000I</td>
			<td></td>
		</tr>
	</tbody>
</table>

3d printing and in situ surface modification via type i photoinitiated reversible addition-fragmentation chain transfer polymerization

3D printing provides facile access to geometrically complex materials. However, these materials have intrinsically linked bulk and interfacial properties dependent on the chemical composition of the resin. In the current work, 3D printed materials are post-functionalized using the 3D printer hardware via a secondary surface-initiated polymerization process, thus providing independent control over the bulk and interfacial material properties. This process begins with preparing liquid resins, which contain a monofunctional monomer, a crosslinking multifunctional monomer, a photochemically labile species that enables initiation of polymerization, and critically, a thiocarbonylthio compound which facilitates reversible addition-fragmentation chain transfer (RAFT) polymerization. The thiocarbonylthio compound, known commonly as a RAFT agent, mediates the chain growth polymerization process and provides polymeric materials with more homogeneous network structures. The liquid resin is cured in a layer-by-layer fashion using a commercially available digital light processing 3D printer to give three-dimensional materials having spatially controlled geometries. The initial resin is removed and replaced with a new mixture containing functional monomers and photoinitiating species. The 3D printed material is then exposed to light from the 3D printer in the presence of the new functional monomer mixture. This allows photoinduced surface-initiated polymerization to occur from the latent RAFT agent groups on the surface of the 3D printed material. Given the chemical flexibility of both resins, this process allows a wide range of 3D printed materials to be produced with tailorable bulk and interfacial properties.

The general procedure for 3D printing and surface functionalization is shown in Figure 1. In this protocol, a network polymer is initially synthesized via a photoinduced RAFT polymerization process15, using a 3D printer to fabricate an object in a layer-by-layer process (Figure 1A). The bulk resin used to form the polymer network contains a photolabile initiating species (TPO), which generates radicals upon exposure to 405 nm lig...

Watch this Scientific Journal Video about 3D Printing and In Situ Surface Modification via Type I Photoinitiated Reversible Addition-Fragmentation Chain Transfer Polymerization at JoVE.com

3D Printing and In Situ Surface Modification via Type I Photoinitiated Reversible Addition-Fragmentation Chain Transfer Polymerization

The present protocol describes the digital light processing-based 3D printing of polymeric materials using type I photoinitiated reversible addition-fragmentation chain transfer polymerization and the subsequent in situ material post-functionalization via surface-mediated polymerization. Photoinduced 3D printing provides materials with independently tailored and spatially controlled bulk and interfacial properties.

3D Printing and In Situ Surface Modification via Type I Photoinitiated Reversible Addition-Fragmentation Chain Transfer Polymerization

3D printing provides facile access to geometrically complex materials. However, these materials have intrinsically linked bulk and interfacial properties ...

This protocol allows the bulk and interfacial properties of 3D-printed materials to be independently tuned. This gives greater flexibility to design and fabricate complex 3D-printed materials. This technique doesn't require stringent reaction conditions and can be performed using commercially available equipment.As a result, this technique makes it significantly easier to fabricate complex 3D-printed materials. To begin, prepare the bulk resin by weighing 0.36 grams of BTPA into a clean 50 milliliter amber vial. Add 13.63 milliliters of polyethylene glycol diacrylate and 14.94 milliliters of DMAm to the amber vial using a micropipette.In a separate 20 milliliter clean glass vial covered with aluminum foil, add 0.53 grams of TPO. Using a micropipette, add 10 milliliters of DMAm to the 20 milliliter glass vial containing the TPO and seal the vial using the cap. Thoroughly homogenize the solution of TPO in DMAm by mixing using a vortex mixer for 10 seconds and then using a standard laboratory sonic bath to sonicate the mixture for 2 minutes at room temperature.Using a glass pipette and rubber pipette bulb, transfer the solution from the 20 milliliter glass vial to the 50 milliliter amber vial and seal the vial with a cap and moldable plastic film. Gently shake the 50 milliliter amber vial and then placed the vial in a sonic bath for 2 minutes at room temperature to ensure the mixture is homogenous. Place the sealed amber vial filled with the bulk resin in a fume hood for later use.Prepare the surface resin as described previously for the preparation of the bulk resin. After preparing the surface resin, place the sealed amber vile filled with the surface resin in a fume hood for later use. To perform 3D printing, pour the previously prepared bulk resin into the 3D printer vat, ensuring that the solution completely covers the bottom film in the vat without any air bubbles or other inhomogeneities, and then close the 3D printer case.Navigate the USB using the 3D printer screen and select the sliced model file by clicking on the triangle Play button to begin the 3D printing process. By watching the 3D printer screen, take careful note of the number of layers printed and pause the printing program by pressing the two vertical lines Pause button during 3D printing of the last layer of the base substrate. Remove the entire build stage and gently rinse the build stage and printed material with undenatured 100%ethanol from a wash bottle for 10 seconds to remove residual bulk resin from the 3D-printed material and the build stage.Using compressed air, gently dry the 3D-printed material and build stage to remove residual ethanol and then reinsert the build stage into the 3D printer. Remove the vat from the 3D printer and pour the remaining bulk resin into an amber vile, and store the vile in a cool, dark place. Using undenatured 100%ethanol from a wash bottle, carefully rinse the vat to remove any residual bulk resin.Dry the vat using a stream of compressed air to remove any residual ethanol and reinsert the vat into the 3D printer. To perform surface functionalization, pour the previously prepared surface resin into the 3D printer vat, ensuring that the solution completely covers the bottom film without any air bubbles or other inhomogeneities, and then close the 3D printer case. Resume the 3D printing program by clicking on the triangle Play button to allow the predetermined surface patterning to occur.Once the printing program has been completed, remove the build stage from the 3D printer and wash for 10 seconds with undenatured 100%ethanol using a wash bottle to remove residual surface resin from the 3D-printed material and the build stage. Using compressed air, gently dry the 3D-printed material and build stage to remove residual ethanol. While still attached to the build stage, post-cure the material by inverting the entire build stage and placing it under 405 nanometer light for 15 minutes.Gently remove the surface-functionalized 3D-printed material from the build stage using a thin metal plate or paint scraper. To perform the fluorescence analysis, place the 3D-printed surface-functionalized material under a 312 nanometer ultraviolet gas discharge lamp in a dark place, ensuring the surface-functionalized layer is facing up. Turn the lamp on to continuously irradiate the surface layer with 312 nanometer light and observe the fluorescent pattern.To perform the tensile property analysis, place the dog bone-shaped specimens between the grips of a tensile testing machine, ensuring the 3D-printed material is equally placed at a distance of 50.3 millimeters. Start the program to acquire force versus travel data. After 3D printing and surface functionalization, the material was post-cured under 405 nanometer irradiation.It was observed that the functionalized materials were yellow but highly transparent with well-defined shapes. The functionalized materials show no fluorescence in the dark. However, upon ultraviolet irradiation, spatially-resolved surface fluorescence was observed in the regions irradiated with light during the surface functionalization step, visible as a slightly raised yin-yang pattern.Fluorescence images showed that the underside of the material showed no fluorescence under ultraviolet light irradiation. However, the top side of the material showed strong fluorescence in the yin-yang pattern. The mechanical properties of the 3D-printed dog bone-shaped samples were analyzed and a stress-strain curve was obtained.The material showed an elastic deformation, providing yield stress of approximately 25 megapascal, and then a plastic deformation before failure. The elongation at break was approximately 12%while the stress at break was about 22 megapascal. The Young's modulus was calculated to be approximately 7 megapascal, while the toughness was approximately 115 megajoule per cubic meter.It's important to make sure that the surface resident completely covers the vat film and is free from air bubbles or other imperfections that may lead to deviations from the intended surface pattern.

3d-printing-situ-surface-modification-via-type-i-photoinitiated

Research

JoVE Journal

Chemistry

3.2K visualizações.  University of New South Wales. Este protocolo permite que as propriedades a granel e interfaciais de materiais impressos em 3D sejam sintonizadas independentemente. Isso dá maior flexibilidade para projetar e fabricar materiais impressos em 3D complexos. Esta técnica não requer condições de reação rigorosas e pode ser realizada usando equipamentos disponíveis comercialmente.Como resultado, essa técnica torna significativamente mais fácil fabricar materiais impressos em 3D complexos. Para começar, prepare ...