Stimuli-responsive polymer colloids: Switchable surfactants for polymers and coatings

“智能”材料的性能会随着环境的变化而发生戏剧性的变化，这就是所谓的“触发器”。物理或化学性质的突然变化在电子产品、医疗保健和工业产品等不同市场中使用的材料的设计中很有用。最近，作者证明了细微分散的聚合物微粒(“聚合物纳米球”)在水中可以快速聚集，产生清水和聚合物纳米球的混合物。这种变化是通过简单地将混合物暴露在空气中而引发的。这种被称为“可切换表面活性剂”的关键材料是一种特殊类型的智能肥皂，当表面活性剂被“开启”时(当存在二氧化碳时)，它可以确保聚合物纳米球保持均匀分散。然而，例如，当二氧化碳的大气被空气取代时，聚合物纳米球聚集在一起，并从悬浮状态中沉淀出来。(可以使用回收的二氧化碳，消除了对温室气体排放的担忧。)聚合物纳米球的分散体广泛应用于许多重要的工业产品，包括乳胶漆、粘合剂涂料和树脂制造。在某些产品中，有必要添加酸或盐等化学物质来破坏分散体的稳定性。这些化学物质要么必须以消费者的代价移除，要么排放到环境中。使用可切换的表面活性剂可以消除这些问题。聚合物纳米球也越来越多地用于专业领域，包括先进的电子学和作为诊断工具的生物医学领域。能够从根本上改变聚合物纳米球分散体的状态，从均匀悬浮到聚集，这可能会在新兴的先进材料领域以及更传统的市场提供巨大的经济机会。该项目将是“可切换表面活性剂”在聚合物纳米球领域的首次应用，并将创造一种新的智能材料。

"Smart" materials undergo dramatic changes in their properties in response to some change in their environment, known as a "trigger". The sudden switch in physical or chemical properties is useful in the design of materials used in diverse markets including electronics, health care and industrial products. Recently, the authors demonstrated that finely divided dispersions of small polymer particles ("polymer nanospheres") in water could be rapidly aggregated to yield a mixture of clear water and polymer nanospheres. This change was triggered by simply exposing the mixture to air. The key material, known as a "switchable surfactant", is a special type of smart soap that ensures the polymer nanospheres remain uniformly dispersed when the surfactant is switched "on" (when carbon dioxide is present). However when the atmosphere of carbon dioxide is replaced by air for example, the polymer nanospheres aggregate and settle out of their suspended state. (Recycled carbon dioxide can be used, eliminating concerns of greenhouse gas emissions.) Dispersions of polymer nanospheres are widely used in many important industrial products, including latex paints, adhesives coatings and resin manufacture. In some products, it is necessary to add chemicals such as acids or salts to destabilize the dispersion. These chemicals must either be removed at a cost to the consumer, or are discharged into the environment. The use of switchable surfactants could eliminate these problems. Polymer nanospheres are also increasingly being used in specialty fields, including advanced electronics and in the biomedical area as diagnostic tools. The ability to radically alter the state of a polymer nanosphere dispersion from uniformly suspended to aggregated may provide significant economic opportunities in both emerging areas of advanced materials as well as in more traditional markets. This project would be the first application of "switchable surfactants" to the field of polymer nanospheres, and would create a new class of smart materials.