Synthesis And Characterization Of The Self-healing PDMS Material Based On Base Pairs

Self-healing material is a new smart material.It is widely researched and applied in many fields,such as medical treatment,architecture,electron device.Hydrogen bond has been a research focus in preparing self-healing material due to its dynamic reversibility and diverse forming-manner.In conventional study,it is complicated but necessary to fabricate a monomer,which can form multiple hydrogen bonds.Nevertheless,there are many hydrogen bonds between base pairs in DNA chain.Hence,it is meaningful to prepare and explore a smart material based on base pairs,which can undergo repeatable fracture-heal.In this task,methacryloyloxyethyl isocyanate(ICEMA)reacts with cytosine(C)and guanine(G),respectively.And ICEMA-C,ICEMA-G can be prepared.The PU-PDMS is achieved by the reaction of bis(3-aminopropyl)terminated polydimethylsiloxane(PDMS)and3-isocyanatomethyl-3,5,5-trimethlcyclohexyl isocyanate(IPDI).Bis(3-aminopropyl)terminated polydimethylsiloxane(PDMS)reacts with methacryloyloxyethyl isocyanate(ICEMA)to obtain PDMS-ICEMA.Lastly,all products are mixed and free radical polymerization happens.The final product is GC-PDMS elastomer.The entire reactions are carried out with no solvent.The process of preparing big monomers is characterized with Fourier transform infrared(FTIR)and~1H NMR spectra.Mechanical properties and self-healing tests of GC-PDMS elastomer are conducted.It is found that the elongation of GC-PDMS reaches 220%and the tensile stress of GC-PDMS is up to 170 k Pa.The healing efficiency of GC-PDMS is about 77%.The GC-PDMS material can carry on healing after repetitive fracture.By improving the healing temperature,the healing time can be obviously decreased.The mechanical properties,which can meet different needs in different occasion,can be tuned by changing the base pairs and the molecular weight of the PDMS.Meanwhile,for further studying the healing influences of base pairs in smart materials,ICEMA-C and ICEMA-G are introduced into polyacrylamide(PAM)to verify the healing effectiveness.Acrylamide(AM)monomer along with ICEMA-C,ICEMA-G,crosslinker N,N-Dimethyl Acrylamide(NAPP)and Tetramethylethylenediamine(TMEDA)catalyst is dissolved in Dimethyl Sulfoxide(DMSO).GC-PAM is prepared in‘one-pot'and synthesized by free radical polymerization.The operation is simple enough.By changing the ratio of the main reactants,the optimal ratio of the products with best mechanical behaviors can be selected.The healing efficiency of GC-PAM is up to 90%and the healing temperature is mild and controllable.The self-healing material have recoverable mechanical performances.Furthermore,the GC-PAM owns perfect microphase separation structure.