The Layer-by-layer or LbL technique is a method for blending polymeric materials under a molecular level control. The properties of the fabricated polyelectrolyte multilayers are tunable and low in defects, which allows for the improvement of mechanical strength. The research presented here is on LbL assemblies in which linear polyethyleneimine (LPEI) is complexed with poly(ethylene-co-methacrylic acid) ionomers (EMAA) which is partially neutralized by sodium in a water/THF mixed solvent system. In the commercial surlyn ionomer aggregations of ionic species, called multiplets, overlap and form reversible ionic clusters that provide EMAA self-healing ability upon a high energy puncture. These clusters as well as other secondary interactions have potential to serve as sacrificial bonds to dissipate mechanical energy upon impact or some other damage event. Applied force, external damage, or pressure wave, such as vibration and sound, all are a form of input of said mechanical energy. We are therefore interested in the damping performance and fracture toughness of the polyelectrolyte blends. This work uses dynamic mechanical analysis (DMA) to study the damping behavior and viscoelastic properties of various pH values of LPEI/EMAA multilayers upon a sinusoidal strain with scanning temperature and frequency. Nano-indentation is employed to determine the mechanical properties by deforming the ionimers-based assemblies elastically. Dissipated energy in both DMA and nano-indentation measurements can therefore be quantifies. The response of the multilayers on thermal heat is also investigated by different scanning calorimetry (DSC). It is found that using the LbL technique to complex LPEI with EMAA alters the microstructure of the EMAA, such as by suppressing crystallinity. The new associations and bonds between the two polymers, however, improve damping behavior demonstrated by an increased amount of energy dissipation.

Damping behavior in polyelectrolyte multilayers containing polyethylene based ionomers

245th National Meeting (2013)

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