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. 2021 Oct 5;33(49):2102900. doi: 10.1002/adma.202102900

Figure 1.

Figure 1

Overview of gelatin‐norbornene (Gel‐NB) synthesis. A) Schematic of the reaction: carbic anhydride (CA) grafting on nonprotonated gelatin‐free amines in pH 9 carbonate–bicarbonate (CB) buffer. B) Illustration of Gel‐NB synthesis methods investigated in this study with varying interval time between sequential addition of CA and pH adjustment. C) Comparison of degree of substitution (DS, left) and norbornene grafting yield (right) obtained with the three different methods in 2 g scale synthesis. The synthesis was performed in 100:1, 50:1, and 10:1 Gel:CA w/w ratio. For DS comparison the right y axis (%) refers only to average values, standard deviations refer to left y axis (mmol g−1). D) Comparison of DS and grafting yield resulting from Gel‐NB synthesis at different reaction scales (2 g, 10 g, 50 g) using the fastest method (M3). The synthesis was performed with different Gel:CA ratio in order to target different DS. For DS comparison the right y axis (%) refers only to average values, standard deviations refer to left y axis (mmol g−1). E) Comparison of Gel‐NB synthesis (≈50% DS) with previous reports using CA.[ 43 , 44 ] Compared to the commonly used protocol developed by Muñoz et al.,[ 43 ] no visible excess of unreacted reagent is obtained upon centrifugation step at pH 7.4 using M3‐based synthesis with 10:1 Gel:CA ratio (left). On the right, main improvements resulting from the use of M3 are highlighted.