Abstract

Waterborne poly(urethane urea)s (PUDs) containing graphene derivatives with different morphologies and surface polarities were synthesized via in situ polymerization by using the acetone method. Small amounts (0.04–0.30 wt.%) of graphene oxide (GO), graphite nanoplatelets (GP) or milled graphite (MG) were mixed with polyadipate of 1,4-butanediol polyol and added during synthesis of the PUDs. The addition of graphene derivatives changed differently the degree of micro-phase separation of the poly(urethane urea)s (PUs) depending on the balance between the extent of covalent interactions between the surface functional groups on the graphene sheets and the isocyanate groups, and the number of stacked graphene sheets. Whereas MG mainly intercalated between the soft segments showing a typical behavior of nanofiller, GP and, particularly, GO showed different degrees of micro-phase separation due to more net covalent interactions with the poly(urethane urea) chains which caused higher crystallinity. The addition of graphene derivative decreased the glass transition temperature of the hard segments and increased the percentages of associated by hydrogen bond urethane and urea groups, more noticeably by adding GP and MG. Lower temperatures of decomposition and higher amounts of urethane and urea hard domains, and soft domains were found in PU + GO and PU + MG, and they showed an additional structural relaxation at 11–16 °C. PU and PU + GP had higher thermal stabilities than PU + GO and PU + MG and the addition of GP and, more markedly, GO imparted toughening to the poly(urethane urea). The T-peel strength values were higher in the joints made with PUD + GO due to the more net covalent interactions between the surface functional groups on the GO sheets and the poly(urethane urea) chains. On the other hand, the lap-shear strength of the joints made with PUD + MG and, in less extent, with PUD + GP noticeably increased.

摘要

通过原位合成含有具有不同形态和表面极性的石墨烯衍生物的水性聚（氨基甲酸酯脲）（PUD）用丙酮法聚合。将少量（0.04-0.30 wt.%）氧化石墨烯（GO）、纳米石墨片（GP）或研磨石墨（MG）与 1,4-丁二醇多元醇的聚己二酸酯混合，并在 PUD 合成过程中加入。石墨烯衍生物的添加改变了聚（氨基甲酸酯脲）（PU）的微相分离程度，这取决于石墨烯片表面官能团与异氰酸酯基团之间的共价相互作用程度之间的平衡，以及堆叠石墨烯片的数量。而 MG 主要插入软段之间，表现出纳米填料的典型行为，GP，特别是 GO，由于与聚（氨基甲酸酯脲）链的更多净共价相互作用导致更高的结晶度，因此表现出不同程度的微相分离。石墨烯衍生物的添加降低了硬链段的玻璃化转变温度并增加了氢键氨基甲酸酯和脲基团的缔合百分比，通过添加 GP 和 MG 更显着。在 PU + GO 和 PU + MG 中发现了较低的分解温度和较高量的氨基甲酸乙酯和尿素硬域以及软域，并且它们在 11-16 °C 时表现出额外的结构松弛。PU 和 PU + GP 比 PU + GO 和 PU + MG 具有更高的热稳定性，并且添加 GP 和更显着的 GO 赋予聚（氨基甲酸酯脲）增韧。由于 GO 片材上的表面官能团与聚（氨基甲酸酯脲）链之间的净共价相互作用更多，因此使用 PUD + GO 制成的接头的 T 剥离强度值更高。另一方面，