湿度对高分子氢键复合物纤维力学行为的影响

Polymer complexes exhibit environmental-responsiveness owing to the integration and assembly of stimuli-sensitive components, leading to the changes in their structure or properties. Humidity is one of the general environmental parameters which can influence the fabrication and application of polymer complexes, and thus it is important to investigate the effect of humidity on the structure and properties of polymer complexes. Herein, three hydrogen-bonding complex fibers were constructed using poly(acrylic acid) (PAA) as a hydrogen-bonding donor, and polyvinylpyrrolidone (PVPON), poly(2-ethyl-2-oxazoline) (PEOX) and poly(ethylene oxide) (PEO) as the hydrogen-bonding acceptors. Results show that the strength of hydrogen-bonding complexation affects the morphology and glass-transition temperature of the prepared complex fibers. With the increase in humidity, PAA/ PVPON fiber stayed in a glassy state while PAA/PEOX fiber presented a glass-transition-like behavior at high humidity. As for PAA/PEO fiber, it showed a rubber-like transition behavior even at low humidity. It is found that the mechanical properties of the complex fibers are different mainly attributed to the different complexation strengthes, chain structures and water contents in the systems. The storage modulus-frequency master curve of polymer complex under humidity field was constructed using time-humidity superposition technique through dynamic mechanical multi-frequency strain test, and the mechanical relaxation in a wide time range was presented. Above all, this work can provide basic guidance for constructing humidity-response materials and analyzing the service capability of polymer complex materials.