Synthesis
The way to make the smart rubbers is to graft H-bonding moieties onto backbones that are already synthesized. This process happens when you use oligocondensation of a mixture of fatty mono, di-, and triacids with diethylenetriamine (DETA). When you change the degree of the backbone branching and the molecular weight by changing the di- and triacids and also by end-capping before the condensation reaction some acid groups with 2-aminoethylimidazolidone (UDETA)which is what helps in the bonding process. The additional H-bonding units are introduced by grafting urea onto all secondary amines of DETA. Analogous synthetic routes with different H-bonding moieties or building blocks of branched backbones can of course be envisaged.
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- In short you graft UDETA onto fatty acids. Then you add DETA. Urea is reacted on the secondary amines of DETA to make 1,1-Dialkylureas. The stoichiometries of DETA and UDETA with the fatty acids give us the control to make the molecular weight different, the branching degrees, and the number of H-bonding moieties for each molecule.
The smart rubber is only made when you synthesize with the highest molecular weight of materials and it also has a particularly long relaxation time. These behave like supramolecular self-healing rubbers or otherwise know as smart rubber.
To get a fine tuned smart rubber with characteristics that you want you just use different fatty acids made from vegetable oils and you also have the option to change the ratio of diacid/triacid.
Read more about this topic: Smart Rubber
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