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International Journal of Bioprinting Amphiphobic encap. for transient devices

formed from crosslinking during 3D printing. These tiny approximately 19.79% and 37.5% longer than 3P/500.
defects facilitate the close interaction between the water The shortest lifetime similar to that of 3P/500 was
droplets and pinholes, favoring water trapping to the less observed when the thickest 1:4:7 PBTPA was stacked
hydrophobic 1:1:2.5 PBTPA and water repulsion to the in the amphiphobic structure among the samples. The
more hydrophobic 1:4:7 PBTPA. This affinity is due to the addition of the less hydrophobic 1:1:2.5 PBTPA layers to
high probability of hydrogen-bond network formation in the more hydrophobic 1:4:7 PBTPA layers significantly
the confined environment, and both interactions can be improves waterproofing. This finding indicates that
conducive to maximizing waterproofing properties. 50 the less hydrophobic 1:1:2.5 PBTPA) is not favorable
In addition, MD simulations were conducted using for inhibiting water penetration, suggesting that the
model compounds. One sample structure consisted less hydrophobic layer imparts a water-trapping effect
of three layers of 1:4:7 PBTPA (hydrophobic PBTPA); (Figure 3A). The less hydrophobic 1:1:2.5 PBTPA comes
another sample structure was designed by modifying the into direct contact with bulk water on the top and traps
1:1:2.5 PBTPA structure to adopt a 1:1:3 ratio and inserting the water within the small pores. Conversely, the more
it between the layers of 1:4:7 PBTPA (amphiphobic hydrophobic 1:4:7 PBTPA demonstrates water blocking.
PBTPA) to analyze the inter-atomic forces between PBTPA In summation, the combination of 3D printing and
layers (Figure S9, Supporting Information). The energy amphiphobic encapsulation strategies enhances the
analysis revealed that after the structures stabilized, the performance and characteristics of the membranes.
electrostatic energy stabilization was 24.2 and 23.4 kcal/ The mechanical properties of amphiphobic PBTPA
mol, respectively. Notably, the amphiphobic structure had were analyzed using a stress–strain curve. 3P/500,
17 hydrogen bonds compared to the hydrophobic structure 3P/50h1-200h2, 3P/100h1-150h2, and 3P/150h1-100h2
with 13 hydrogen bonds. In comparison to the 1:4:7 samples displayed an elongation of 45.25%, 40.20%,
PBTPA structure, the 1:1:3 PBTPA structure has a smaller 37.78%, and 30.78%, respectively (Figure 3E and F; n
size, contributes less to energy stabilization, and has fewer = 4). Notably, an increase in the ratio of 1:1:2.5 PBTPA
atoms available for hydrogen bonding. The amphiphobic makes it softer and more stretchable than 1:4:7 PBTPA,
structure essentially has more hydrogen bonds due to fewer resulting in decreased elongation and Young’s modulus.
defects in 3D printing, thereby facilitating more efficient Contrary to Young’s modulus in Figure 3E, Figure 3F
interactions with water. The conjunction of the two effects displays a 1:4:7-PBTPA-thickness-proportional elongation
further inhibits water penetration. at break. The amphiphobic PBTPA structure features a
The amphiphobic PBTPA was fabricated by sandwiching higher overall Young’s modulus, particularly for 3P/50h1-
1:4:7 PBTPA between 1:1:2.5 PBTPAs. In Figure 3B, 200h2 (containing lesser 1:1:2.5 PBTPA). The slightly
the thickness of the 1:1:2.5 and 1:4:7 PBTPA layers are decreased elongation and increased Young’s modulus
denoted as h1 and h2, respectively. The total thickness are still desirable compared to the screen-printed layer
of the amphiphobic PBTPA was maintained at 500 µm. (SP/500). Nonetheless, the amphiphobic multilayered
The as-prepared amphiphobic PBTPA was photographed PBTPA structure can significantly enhance the lifetime
with an exaggeration of the width of each PBTPA layer of electronics with slight reductions in the elongation and
(Figure 3C). The layers of amphiphobic PBTPA (i.e., Young’s modulus.
1:1:2.5 PBTPA and 1:4:7 PBTPA) were carefully integrated The effect of the number of amphiphobic stacks
without any air gap or weak adhesion between the samples. was also investigated in Figure 4. The selected number
Notably, the less hydrophobic 1:1:2.5 PBTPA is more of stacks to be compared was 1, 3, 5, and 10. 3P/500
sensitive to water absorption due to the higher content of and 3P/150h1-100h2 were selected as representative
hydrophilic constituent, 4PA. Nonetheless, 3D printing amphiphobic samples for stacking numbers 1 and 3,
30
has enhanced the durability of the amphiphobic PBTPA respectively. Alternating layers of 1:1:2.5 PBTPA and 1:4:7
despite the strong presence of 4PA, and the amphiphobic PBTPA, totaling 5 or 10 layers, were stacked at 100 and
PBTPA displayed relative stability for more than 3 months 50 µm, respectively. They were named 3P/(100*5)
amphiphobic
in a 37°C aqueous environment. and 3P/(50*10) , respectively (Figure 4A). Our
amphiphobic
The EDR tests compared the waterproofing findings revealed that the number of amphiphobic stacks
performance of amphiphobic PBTPAs (Figures 3D and significantly affects the waterproofing properties of the
S2, Supporting Information). The measured lifetimes amphiphobic layer (Figure 4B and C). The lifetime of the
were 46 h for 3P/50h1-200h2, 57.5 h for 3P/100h1- amphiphobic layers increased with the number of stacks,
150h2, and 66 h for 3P/150h1-100h2. For 3P/100h1- i.e., from 48 h (3P/500) to 66 h (3P/150h1/100h2), 105
150h2 and 3P/150h1-100h2, the lifetimes were h (3P/[100*5] ), and 125 h (3P/[50*10] ),
amphiphobic amphiphobic

Volume 10 Issue 5 (2024) 314 doi: 10.36922/ijb.3871