Fig. 1
From: Linear elasticity of polymer gels in terms of negative energy elasticity
a Tetra gel synthesized by AB-type cross-end coupling of two kinds of precursors of equal size in a water solvent.These precursors are tetra-arm poly(ethylene glycol) (PEG) chains whose terminal functional groups (A and B) are mutually reactive. b Control parameters of the network density of the tetra gel. In the polymer network after completion of the chemical reaction, the molar mass of precursors M corresponds to the molar mass between the crosslinks (M/2), and the polymer concentration c represents the number density of crosslinks n as n = cNA/M. Here, NA is the Avogadro constant
