Cure reaction for modified diallylbisphenol A/diaminodiphenylsulfone/bismaleimide

"Self-Lockable" Liquid Crystalline Diels-Alder Dynamic Network Actuators with Room Temperature Programmability and Solution Reprocessability

Novel main-chain liquid crystalline Diels-Alder dynamic networks (LCDANs) were prepared that exhibit unprecedented ease for actuator programming and reprocessing compared to existing liquid crystalline network (LCN) systems. Following cooling from 125 °C, LCDANs are deformed with aligned mesogens self-locked at room temperature by slowly formed Diels-Alder (DA) bonds, which allows for the formation of solid 3D actuators capable of reversible shape change, and strip walker and wheel-capable light-driven locomotion upon either thermally or optically induced order-disorder phase transition. Any actuator can readily be erased at 125 °C and reprogrammed into a new one under ambient conditions. Moreover, LCDANs can be processed directly from melt (for example, fiber drawing) and from solution (for example, casting tubular actuators), which cannot be achieved with LCNs using exchangeable covalent bonds. The combined attributes of LCDANs offer significant progress toward developing easily programmable/processable LCN actuators.

Electron beam curing of functionalized N-(4-hydroxy phenyl)maleimide monomers

Electron beam (E-beam) curing by different total radiation doses (100, 200, 300 and 400 kGy at 10 kGy per pass) of functionalized maleimides (20%) [ N-(4-acryloyloxy phenyl)maleimide, N-(4-methacryloyloxy phenyl)maleimide and N-(4-cyanato phenyl)maleimide] is carried out using N-vinyl-2-pyrrolidone as the reactive diluent (80%). The swelling studies indicate the presence of highly cross-linked structure in the polymer derived from cyanate-functionalized maleimide cured using 400 kGy electron beam (E-beam) irradiation. The thermal stabilities of all the polymers are studied using thermogravimetric analyzer. The materials cured using the highest radiation dose (400 kGy) are found to have better thermal stability compared to other materials cured using lower doses (100, 200 and 300 kGy at 10 kGy per pass). The degradation kinetic studies using the Vyazovkin method showed that the activation energies for the thermal degradation of polymeric materials got by E-beam irradiation of the monomers at 400 kGy are higher. Of all the materials investigated, liquid composition having N-(4-cyanato phenyl)maleimide (20%) and N-vinyl-2-pyrrolidone (80%) cured by E-beam radiation (400 kGy) showed better thermal stability.