Study On Waterborne Shape Memory Polyurethane

A series of shape memory polyurethane (SPU) aqueous dispersions were prepared, in which four different polyester diols such as polycaprolactone (PCL-3000), poly(butylene adipate) (PBA-3000), poly(hexylene adipate) (PHA-3000), poly(butylene sebacic acid) (PBSe-3201) with 3000 molecular weight were used as soft segments. The results showed that PCL based SPU showed the greatest tensile strength, Young modulus and the elongation. PBA based SPU exhibitted the highest water vapor transmission(WVT) and the shape recovery ratio, while the PBSe-3201 based SPU had excellent shape fixity ratio due to its high crystallinity.A series of poly(adipic acid-hexanediol-ethylene glycol) ester diols with different ethylene glycol (PEG-200, Mn= 200) content were synthesized, and the corresponding SPU aqueous dispersions were prepared based on these polyester diols. It was found that the particle size of the aqueous dispersions and the microphase separation degree between the soft and hard segment in the SPU films increased with the increasing of the PEG-200 content in the polyester diols. In addition, the tensile strength and the shape-recovery ratio of the SPU films increased with the introduction of the PEG-200 in the diols but decreased with further adding of it when the PEG-200 content in the polyester polyol is more than 5%, while the WVT and the water vapor permeation(WVP) both increased significantly.Poly(hexylene adipate) based SPU aqueous dispersions with different PEG-200 content in the hard segments were prepared. With the increase of the PEG-200 content, the particle size of the aqueous dispersions increased while the apparent viscosity decreased. Moreover, the microphase separation and the water absorption of the SPU films increased while the crystallinity of SPU films decreased with the introduction of the PEG-200 to the SPU. The shape recovery temperature, the WVT and the shape recovery ratio of the SPU films increased with the adding of a small amount of PEG-200, but decreased with further adding of it.A series of poly(butylenes adipate) based SPU aqueous dispersions were synthesized successfully. The results showed that the crystallinity of soft segments and the degree of hydrogen bonds for urea groups in the SPU increased, giving rise to an increased microphase separation degree between the hard and the soft segments in the SPU with the adding of ODO to the SPU. The shape fixity ratio and the shape recovery temperature of the SPU films increased and the shape fixity ratio of the SPU films decreased a little after ten times tensile test with the introducing of the ODO to the SPU films.