I recently saw this video of super-swellable polymer and felt inspired. Printing a swellable structure would be sort of interesting. However, sodium polyacrylate isn't a printable material. Does anyone know of a material that is? Preferably, swelling activated by water.

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    $\begingroup$ sodium polyacrylate is also the primary component of a product known as water beads, small spheres which increase substantially in size when placed in water. For 3D printing, one might expect that the powder could be combined with filament material during manufacture, although I am unfamiliar with the reaction of sodium polyacrylate and heat. It's an interesting thought experiment to consider combining PVA (water soluble support) and sodium polyacrylate. When you add water, the entire structure crumbles? $\endgroup$ – fred_dot_u May 26 '18 at 15:32
  • $\begingroup$ @fred_dot_u - Would you like to make that comment an answer? $\endgroup$ – Greenonline Jul 30 '18 at 9:48
  • $\begingroup$ If you believe that it's a suitable answer, I can indeed convert it, but the question was if a material exists and I don't know of any, hence my hedge-type comment. $\endgroup$ – fred_dot_u Jul 30 '18 at 14:16

The video treats about sodium polucarbonate ‎(C3H3NaO2) this is a superabsorbent polymer has the ability to absorb as much as 100 to 1000 times its mass in water. This is used as desiccant on products that moisture can be a problem basically during storage prior selling. The video shows the water how is trapped inside the particles of sodium polycarbonate, this happens inside a diaper or any product urine odor absorbing, also is used on waste liquid control.

Also you can find something similar on some products that has a little bag that says silica gel (SiO2).

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  • $\begingroup$ I mean, that's cool and all. sodium polyacrylate is the same. However, I was hoping for something 3D printable. $\endgroup$ – User2341 May 31 '18 at 19:13
  • $\begingroup$ @User2341 There is no data about melting point of this material, however can be dried again at 150°C, so assume that can be mixed with other material buy it will result as fragile. If you want to use for some action figures I recommend to use a molding process; I remember that we used to play with a kind of toys that grows on water. $\endgroup$ – Fernando Baltazar May 31 '18 at 20:55
  • $\begingroup$ My real hope in asking this question was to find something ready to be printed, rather than make my own printing material $\endgroup$ – User2341 Jun 1 '18 at 18:11

There appear to be at least two papers which revolve around the use of hydroxypropyl cellulose (HPC) filaments.

This proposal/article, from Journal of Drug Delivery Science and Technology 30 July 2015 seems to, at least, partially fit your criteria, 3D Printing by Fused Deposition Modeling (FDM) of a Swellable/Erodible Capsular Device for Oral Pulsatile Release of Drugs by Melocchi et al.:

The aim of the present work was to explore the feasibility of fused deposition modeling (FDM) 3D printing in the manufacturing of capsular devices for oral pulsatile release based on a swellable/erodible polymer (hydroxypropyl cellulose, HPC). This involved an experimental evaluation of the possibility of fabricating hollow structures via FDM and the production of HPC filaments by hot melt extrusion (HME), which are not commercially available. Moreover, the set-up of appropriate computer aided design files had to be faced. A twin-screw extruder equipped with a rod-shaped die and a purposely designed pulling/calibrating device as well as a MakerBot Replicator 2 3D printer were employed for HME and FDM processing, respectively. Bodies and caps with satisfactory physico-technological properties were obtained. The release test of assembled capsular devices pointed out a lag phase before rapid and quantitative liberation of the drug. The morphological changes undergone by the device when in contact with water and their release performance turned out comparable with those of analogous systems fabricated by injection molding. The possibility of manufacturing capsular devices for oral pulsatile release by FDM 3D printing starting from HPC filaments purposely prepared was thus demonstrated, and the real-time prototyping potential of FDM was assessed.

3D Printing by Fused Deposition Modeling (FDM) of a Swellable/Erodible Capsular Device for Oral Pulsatile Release of Drugs | Request PDF. Available from: https://www.researchgate.net/publication/282800986_3D_Printing_by_Fused_Deposition_Modeling_FDM_of_a_SwellableErodible_Capsular_Device_for_Oral_Pulsatile_Release_of_Drugs [accessed Jul 30 2018].

Also, from Manufacturing and characterization of £D printing filament by tailoring materials by V. Mirón, S. Ferrándiz*, D. Juárez, A. Mengual

There are also references to the pharmaceutical field’s manufactured materials as it reflects Melocchi 4 in his paper about filaments based on insoluble (ethylcellulose, Eudragit RL), promptly soluble (polyethylene oxide, Kollicoat1 IR), enteric soluble (Eudragit1 L, hydroxypropyl methylcellulose acetate succinate) and swellable/erodible (hydrophilic cellulose derivatives, polyvinyl alcohol, Soluplus1) polymers were successfully produced

There is also this, which refers to the Melocchi paper above, Fused Deposition Modeling (FDM) 3D Printed Tablets for Intragastric Floating Delivery of Domperidone:

Domperidone (DOM)... DOM was successfully loaded into hydroxypropyl cellulose (HPC) filaments using hot melt extrusion (HME).


Several novel gastroretentive delivery systems have been explored to overcome the shortcomings above, including polymer bioadhesive systems, swelling and expanding systems, high-density systems and floating systems3

An image of the filament is shown in figure 1:

Image of HME fabricated filaments

However, as a commercially available filament, you might be out of luck, or at least hard pushed to find one.

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