Preparation And Properties Of Crosslinked Polymers Based On Schiff-base Reaction

Schiff base can be formed between amines and aldehydes by the reversible condensation,which is one of the oldest and most ubiquitous reactions in organic chemistry.This kind of reaction involves two distinct processes: imine condensation/hydrolysis and imine exchange,which provides the basis for being remolded and self-healing.Besides,Schiff base can be formed by commercial available raw materials easily,so it's widely used in our daily life.In this text,we will do research on the following two routes.First,crosslinked polymers are fabricated by dynamic bonding linkage based on Schiff base reaction between commercial available terephthalaldehyde(A2)and diamine(B2)using tri(2-aminoethyl)amine(B3)as crosslinking agent.The network could be easily tailored by changing the ratio of B3 to B2(R)and increasing R could lead to increasing the crosslinking degree.As a result,the sample could be gradually changed from weak to strong materials with increasing R based on the data of mechanical properties.Most importantly,this type of crosslinked polymers could show good self-healing and remolded behavior.The crosslinked sample could also be remolded at 120 °C under hot pressure without the compromise of its mechanical properties and the temperature for self-healing could be controlled from room temperature(~20 °C)to 55 °C based on the different R.In the meantime,they could also be completely degraded into small molecules under the acidic condition for 2 days.All these characters could provide an ideal solution to the crosslinked polymers which is totally friendly to the environment.Secondly,a series of prepolymers with amine terminated are fabricated by dynamic bonding linkage based on Schiff base reaction between terephthalaldehyde and 4,7,10-Trioxa-1,13-Tridecanediamine.Then crosslinked polymers are formed with Bisphenol-A epoxy resin as crosslinking agent.The network could be easily tailored by changing the segment length.As a result,mechanical properties of the sample could be changed with different segment agent.However,the self-healing ability of the materials is relatively worse because of the introduce of the irreversible covalent bond.Besides,the degradation of the material couldn't completely reach.