不同软段结构的双离子型聚氨酯离聚体

本文讨论了以聚环氧乙烷(PEO)、聚环氧丙烷(PPO)以及聚丁二烯(PBD)为软段,以4,4’-二异氰酸二苯甲烷(MDI)和N,N-二羟乙基甲胺(MDEA)为硬段的链段型聚氨酯的合成。并通过MDEA中的第三胺与Υ-丙磺内酯反应,转化为双离子型离聚体。用差示扫描量热、红外光谱、动态力学性能以及应力-应变等实验方法研究了化学组成和氨磺化程度对材料相分离程度,力学性能和形态结构的影响。结果表明,离子化后的材料力学性能有很大的改善。对PBD为软段的材料,离子化只能提高硬段“微区”的内聚能,而对PEO、PPO为软段的材料,还能大大提高软、硬相的相分离程度。

STUDY OF SEGMENTED POLYURETHANE ZWITTERIONOMERS WITH DIFFERENT SOFT SEGMENTS

Three series of segmented polyurethanes were synthesized, which are based on 4,4'-methylene-di(phenyl isocyanate) (MDI), N-methyl diethanolamine (MDEA) and hydroxy terminated poly-butadiene, poly(propylene oxide) or poly(ethylene oxide). The tertiary amine of MDEA was sulfonated with γ-Propane sultone, thereby converting these polyurethanes into zwitterionomers. The effects of the chemical composition and the level of ammonium sulfonation on the extent of phase separation, physical properties and morphologies were studied using differential scanning calorimetry, dynamic mechanical analysis, stress-strain testing and IR spectrometry. The results show that:1, For the polyurethanes studied, the miscibility of different soft segments with hard segment is in the order of PEO>PPO>PBD. The PEO polyurethane is nearly homogeneous but the material based on PBD exhibits almost complete microphase separation.2, Ammonium sulfonation shifts the soft segment Tg of PPO and PEO based polymers to lower temperatures, suggesting that ionization improves microphase separation. The soft segment Tg of the polybutadiene system is uneffected by ionization. The tensile properties are improved dramatically with increasing the degree of ionization.3, IR analysis showed that the sulfonate ion SO3- not only associated with the counter ionon the chain extender but also formed hydrogen bond with -NH of urethane linkage.