In this paper, we present the relationship between printing parameters of a 3D gel printer "Soft and Wet Intelligent Matter-Easy Realizer (SWIM-ER)" and mechanical properties of the fabricated gel objects by SWIM-ER. The printer is able to fabricate hydrogel objects by scanning of ultra-violet (UV) light irradiation (photopolymerization). Various hydrogels objects were printed with different scanning velocity of UV light. We measured the water content and mesh sizes of gel objects utilizing Scanning Microscopic Light Scattering (SMILS). Furthermore, we also printed the gel objects with multiple scan rates with constant UV light irradiation energy, and measured sizes of gel objects, and performed the compression test. It was observed that the physical properties of printed hydrogel objects are strongly related with 3D printing parameters (scan velocity and number of scans-scan rate) due to difference in crosslinking density of polymer network.
Abstract:In order to construct the artificial cells and to understand the physicochemical properties of living cells, it is important to clarify the cell-sized confinement effect on the behaviours of bio-inspired polymers. We report the dynamic behaviours of aqueous hydroxypropyl cellulose (HPC) solution coated with phospholipids in oil (water-in-oil droplets, W/O droplets), accompanied by an increase in the temperature. We directly observed the beginning of phase separation of HPC solution using a fluorescence microscope and confirmed the dependence of such phenomena on droplet size. The results indicate that the start time of phase separation is decreased with an increase in droplet size. The experimental results suggest that the confinement situation accelerates the phase separation of aqueous HPC solutions.
Crosslinkers play an essential role in determining the physical properties of gels. We synthesized a new type of crosslinker with three vinyl groups [trisacrylaminomethan (TRI), which joins six polymer chains per single molecule]. We found that N-isopropylacrylamide (NIPA) gels crosslinked with the new crosslinker gel at a much lower fraction of crosslinker than the gel crosslinked with popular N,N'-methylenebisacrylamide (BIS). We also found that the NIPA gels with TRI crosslinker displayed larger discrete volume changes at the volume phase transition. We discuss the effects of the average length of NIPA chains between two crosslinkers on the volume phase transition as well as the effects of inhomogeneity in gels caused by a low fraction of crosslinker.
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