Fig. 3: Replicating silicone gels mechanics with solvent-free injectable elastomers.

a True stress vs. elongation curves of injectable elastomers prepared with different NCO:OH molar ratios. The decrease in crosslink density (1:1→1:8) results in concurrently decreasing softness (\({E}_{0}\)) and firmness (β). b Comparison of true stress-elongation curves of injectable elastomers with similar \({E}_{0}\) but different β relative to a commercial silicone gel with 70 wt% of sol fraction, and to different examples of weakly strain-stiffening biological tissues (e.g., chicken gut and dog lung)²⁷. c Good agreement between experimental (\({\lambda }_{{\max },{\exp }}\)) and theoretical (\({\lambda }_{{\max },{theo}}={\beta }^{-0.5}\)) elongations-at-break suggests uniform mesh dimensions of injectable elastomers. d Linear correlation between the structural modulus (\(E\)) and \({\beta /(1+{n}_{{sc}})}^{3/2}\) validates architecturally tuning the mechanical properties of injectable brush elastomers. e Texture profile analysis (TPA) of the injectable elastomer NCO:OH 1:8 at different strain ratios of 20, 50, and 70%. f Comparing the TPA parameters (springiness, resilience, and cohesiveness) of the injectable elastomer NCO:OH 1:8 with the commercial silicone gel implant at different strain ratios of 20, 50, and 70%. At least n = ten independent TPA measurements of k = 3 independently prepared samples were conducted. Height of histogram bins and the error bars correspond to mean values ± standard deviation (SD), respectively.