Here, we extend these results by introducing a second level of reinforcement into peptidereinforced APCNs by incorporating CNCs. However, the hydrophilic nature of CNCs is a major drawback in the synthesis of CNC-reinforced APCNs, as they are difficult to disperse homogeneously in the hydrophobic monomer mixture used in the synthesis of PHEA-l-PDMS APCNs. The CNCs tend to form aggregates that are inefficient in reinforcing the material. Certain modification techniques such as carbamation, esterification, and sialylation have been used to increase the hydrophobicity of the CNCs to make them miscible with hydrophobic monomers, solvents, or polymers. For example, 2-ureido-4[1H]pyrimidinone (UPy)-modified CNCs allowed production of nanocomposites based on poly(ethylene), polystyrene-block-polybutadieneblock-polystyrene elastomers and poly(ethylene oxide-co-epichlorohydrin), with increased stiffness and strength, while still maintaining a high strain-at-break. Here, we use hydrophobically modified cellulose nanocrystals (HCNCs) to prepare CNCreinforced APCNs based on the hydrophobic crosslinker, α,ω-methacrylate functionalized PBLA5b-PDMS-b-PBLA5 that contains β-sheet-forming PBLA peptide blocks, which provide additional physical crosslinks by hydrogen bonding and enhance the mechanical properties of the material. This functionalized peptide hybrid crosslinker was used to crosslink hydrophobically masked trimethyl silyl 2-hydroxyethl acrylate (TMS-HEA) to yield hydrophobic precursor networks that were then converted into APCNs by cleaving off the TMS groups. The bio-inspired, two-level, hierarchical reinforcement of APCNs resulted in APCNs that were reinforced in both the dry and water-swollen states.