Fig. 1: Synthesis of injectable non-leachable elastomers with tunable gelation time for biomedical applications.
a Injectable tissue-mimetic elastomers composed of random polydimethylsiloxane-poly(ethylene glycol) (PDMS-r-PEG) brush copolymers with a controlled fraction of end-functionalized side-chains and a linear difunctional crosslinker. Inset: AFM micrograph of bottlebrush melt (\({n}_{{sc}}\)14, \({n}_{{bb}}\)889) (sale bar 50 nm) shows densely packed worm-like macromolecules (Supplementary Fig. 12, Supplementary Table 3). b Demonstrating solvent-free injection and curing of a premixed dual component injectable formulation into an elastomer with a tissue-like deformation response (Supplementary Video 1). c Examples of coupling chemistries to crosslink functionalized bottlebrushes. d Evolution of the storage (G′) and loss (G″) moduli as a function of time for injectable elastomers with either OH-functionalized (slow-cure gelation, \({t}_{{gel}}\) ~ hours) or NH2-functionalized (fast-cure gelation, \({t}_{{gel}}\) ~ minutes) brush chain ends cured with a macromolecular diisocyanate crosslinker. e Polydimethylsiloxane (PDMS) melts with varying architecture (linear, bottlebrush, and star-like bottlebrush) and a similar molecular weight Mn ≅ 500,000 demonstrate significant decrease of zero-shear complex viscosity (\(\eta \ast\)) with branching. Further, bottlebrushes with longer side chains, yet similar molecular weights (\({n}_{{sc}}\)14, \({n}_{{bb}}\)1540 vs. \({n}_{{sc}}\)70, \({n}_{{bb}}\)304) possess lower melt viscosity (Supplementary Fig. 13).
