Amphoteric surfactants have long hydrophobic hydrocarbon chain and hydrophilic positive as well as negative charged center connected with each other by a spacer group. Thus, this type of surfactant maintains overall charged neutrality. The properties of amphoteric surfactants depend primarily on the length of the hydrophobic hydrocarbon chain, the number of methylene segments in the spacer, the positive and negative charged groups, and their relative position. The ionic activity of amphoteric surfactants is influenced according to the pH value of the solvent. They display cationic behavior below the isoelectric points and anionic behavior at a higher pH. They take the shape of zwitterions in the area of the isoelectric point. In fact, amphoteric surfactants can be parted into pH-sensitive and pH-insensitive surfactants. The pH-insensitive surfactants stay as zwitterionic form irrespective of the pH of the solution. This surfactant has some unique features because of its precise molecular structure as follows: high water solubility, high surface activities, a wide isoelectric range, low critical micelle concentration (CMC), high foam stability, low toxicity, low irritating, excellent biodegradability, bioactivity, interface change, and so on. Because of these special characteristics, amphoteric surfactants have been immensely interested in many applications in the scientific community, including cosmetics, chromatography, enhanced oil recovery, electrochemistry, nanoscience, polymer chemistry, and waste water treatment. This review aims to study about amphoteric surfactants, which have only one hydrophobic hydrocarbon tail and two oppositely charged hydrophilic headgroups connected with each other by a spacer group and its properties, applications in various academics and industrial fields.

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两性表面活性剂的性质及应用：简述

两性表面活性剂具有长的疏水烃链和亲水的正负电荷中心，通过间隔基团相互连接。因此，这种类型的表面活性剂保持整体带电中性。两性表面活性剂的性质主要取决于疏水烃链的长度、间隔基中亚甲基链段的数量、带正电和负电的基团以及它们的相对位置。两性表面活性剂的离子活性受溶剂pH值的影响。它们在等电点以下表现出阳离子行为，在较高的 pH 值下表现出阴离子行为。它们在等电点区域呈两性离子形状。事实上，两性表面活性剂可分为对pH敏感和对pH不敏感的表面活性剂。无论溶液的 pH 值如何，对 pH 值不敏感的表面活性剂都保持两性离子形式。这种表面活性剂因其精确的分子结构而具有一些独特的特性：高水溶性、高表面活性、宽等电范围、低临界胶束浓度（CMC）、高泡沫稳定性、低毒性、低刺激性、优异的生物降解性、生物活性、界面变化等等。由于这些特殊特性，两性表面活性剂在科学界的许多应用中引起了极大的兴趣，包括化妆品、色谱、提高采油率、电化学、纳米科学、聚合物化学和废水处理。本综述旨在研究两性表面活性剂，