High performance polyimides containing bio-molecule adenine building block from DNA

A series of PIs (APIs) containing naturally occurring adenine moiety in polymer backbone has been prepared from adenine-containing diamine (p-APA) and commercial dianhydrides by a two-step polymerization process. FTIR study confirmed the structures of APIs. The hydrogen-bonding interactions of APIs were studied by FTIR, in-situ FTIR and theoretical methods. The crystalline behavior of APIs were studied by XRD, and the results showed that the APIs have relatively high degree of crystalline. Birefringence and polarized ATR FTIR studies showed that the groups and chains in API films could be simultaneously self-arranged in the in-plane direction without any further stretching. Molecular simulation methods were introduced to study the relationship between self-arranged in-plane orientation and hydrogen-bonding interactions. Thermogravimetric analysis (TGA) showed that the 5% weight loss of APIs (T5) are in the range of 511–569 °C in nitrogen, and the char yields (CR) of APIs are in the range of 55–67% under nitrogen condition. Dynamic mechanical analysis showed that the glass-transition temperature (Tg) are in the range of 315–400 °C. The mechanical properties were studied by universal strength tester, and the results showed that the tensile modulus of API films were in the range of 4.43–9.21 GPa, and the tensile strength of API films were in the range of 124.9–162.9 MPa. Thermal mechanical analysis showed that the in-plane CTE of APIs are in the range of −5.85–37.82 ppm/°C.