| dc.description.abstract | Polyacrylic acid (PAA) used for dispersants and biocompatible matrices in medical glue can form hydrogen-bonded precipitates with other water-soluble polymers (e.g., poly(ethylene oxide), polyvinylpyrrolidone, …etc.) readily in water. Dependent on the type of proton acceptor polymers, the precipitates can be developed into different kinds of materials, including nanosized aggregates, concentrated solutions of associated polymers, hydrogels, elastomers, and polymeric composites. In this work, the effect of the polymer molecular weight on the mechanical properties of the hydrogen-bonded precipitates is studied. It is found that in general, the water content of the polymer complex decreases but its mechanical strength grows, as the molecular weight of donor or acceptor is increased. Both hydrogel and elastomer exhibit the solid-like behavior (G’>G”) and possess the self-healing ability owing to the regeneration of hydrogen bonding. However, hydrogels have lower mechanical strength characterized by the oscillatory test, while elastomers have higher mechanical strength characterized by the tensile test. Similar to PAA with small molecular weight, tannin (TA) has multiple hydrogen-bonding sites for developing a network structure (hydrogel) with proton acceptor. However, the mechanical strength of the polymer complex is sensitive to the mole fraction of tannin. As a crosslinker, TA yields a stronger polymer complex than PAA with a small molecular weight. Because of the planar configuration of TA, the outcomes of the precipitation between TA and polymers (PEO or PVP) depend on the polymer structure, in addition to the strength of hydrogen bonding. | en_US |