Impact of PEGDA photopolymerization in micro-stereolithography on 3D printed hydrogel structure and swelling

• Published in: Soft matter Vol. 17; no. 3; pp. 7188 - 7195
• Main Authors: Alketbi, Afra S, Shi, Yunfeng, Li, Hongxia, Raza, Aikifa, Zhang, TieJun
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 05.08.2021
• Subjects: 3-D printers; Atomic force microscopy; Bending; Crosslinking; Curing; Densification; Hydrogels; Light intensity; Lithography; Luminous intensity; Microscopy; Molecular dynamics; Molecular structure; Photopolymerization; Polymers; Pore formation; Raman spectra; Raman spectroscopy; Scanning electron microscopy; Simulation; Spectrum analysis; Structural analysis; Structural integrity; Swelling; Three dimensional printing
• ISSN: 1744-683X; 1744-6848; 1744-6848
• DOI: 10.1039/d1sm00483b

3D printing complex architectures of responsive-hydratable polymers are enabled by stereolithography via photopolymerization. Yet, insufficient crosslinking leads to compromised structural integrity of the photopolymerized samples, which affects the functionality and reliability of hydrogel devices significantly. Here we investigate how curing parameters and ink formulation affect 3D printed PEGDA samples by using a combination of microfabrication, structural characterization, and reactive coarse-grained molecular dynamics simulation. Our findings show that the degree of curing exhibits a graded profile from confocal Raman spectroscopy and submicron pores from atomic force microscopy, both of which are also observed in our molecular simulations. Moreover, with environmental scanning electron microscopy, we probe the microscopic swelling and bending dynamics of 3D printed hydratable PEGDA structures as well as their structural integrity. Our in-depth characterization results reveal how hydrogel elasticity and irreversible densification due to pore formation highly depends on the exposure time, light intensity and the associated degree of crosslinking. This work provides new molecular insights into processing-structure relation in stereolithography 3D printing. Molecular insights into PEGDA photopolymerization in SLA 3D printing are revealed through spectroscopic, microscopic and computational studies. The impact of processing parameters on microscale swelling dynamics of hydrogels is investigated.