Tensile tests were carried out on an Instron 5566 frame at a tensile rate of 1.0 mm /min using a load cell of 5N. Due to the low range of the load cell, a customised plastic clamp set was used. The hybrid samples were carefully clamped with 1 mm elastomer material on either side of the hydrogel. Measurements were carried out using the software Bluehill 2 to control the Instron equipment and data were acquired every 10 ms. A digital camera, Celestron, was used to monitor the failure behaviour of the structure. The mechanical properties of hydrogels were determined from the stress-strain curve using the initial region of low extension (0-0.01 λ). For calculations of the moduli of the gels (apparent Young's modulus), it was assumed that the elastomers used in our bonding experiments were not under significant strain, and, thus the length of the hydrogel segment (i.e 5 mm) was considered as the length of the sample characterised. Although this assumption is incorrect, it afforded an apparent Young's modulus that we could compare to expected moduli of constitutive materials of the hybrids formed. The energy absorption per unit volume of material up to rupture, namely tensile toughness, was determined from integration of the stress-strain traces, using Origin.