Etika Krishna C, Jochum Florian D, Cox Michael A, Schattling Philipp, Theato Patrick, Grunlan Jaime C
Department of Mechanical Engineering, Materials Science and Engineering Program, Texas A&M University, College Station, Texas 77843-3123, USA.
Macromol Rapid Commun. 2010 Aug 3;31(15):1368-72. doi: 10.1002/marc.201000170. Epub 2010 Jun 22.
Poly(N-ispropylacrylamide) [PNIPAM] is a widely studied polymer for use in biological applications due to its lower critical solution temperature (LCST) being so close to the human body temperature. Unfortunately, attempts to combine carbon nanotubes (CNTs) with PNIPAM have been unsuccessful due to poor interactions between these two materials. In this work, a PNIPAM copolymer with 1 mol-% pyrene side group [p-PNIPAM] was used to produce a thermoresponsive polymer capable of stabilizing both single and multi-walled carbon nanotubes (MWNTs) in water. The presence of pyrene in the polymer chain lowers the LCST less than 4 °C and the interaction with nanotubes does not show any influence on LCST. Moreover, p-PNIPAM stabilized nanotubes show a temperature-dependent dispersion in water that allows the level of nanotube exfoliation/bundling to be controlled. Cryo-TEM images, turbidity, and viscosity of these suspensions were used to characterize these thermoresponsive changes. This ability to manipulate the dispersion state of CNTs in water with p-PNIPAM will likely benefit many biological applications, such as drug delivery, optical sensors, and hydrogels.
聚（N-异丙基丙烯酰胺）[PNIPAM]是一种被广泛研究用于生物应用的聚合物，因为其低临界溶液温度（LCST）非常接近人体温度。不幸的是，由于这两种材料之间相互作用不佳，将碳纳米管（CNT）与PNIPAM结合的尝试一直未成功。在这项工作中，一种含有1摩尔％芘侧基的PNIPAM共聚物[p-PNIPAM]被用于制备一种热响应聚合物，该聚合物能够在水中稳定单壁和多壁碳纳米管（MWNT）。聚合物链中芘的存在使LCST降低不到4°C，并且与纳米管的相互作用对LCST没有任何影响。此外，p-PNIPAM稳定的纳米管在水中表现出温度依赖性分散，这使得纳米管的剥离/聚集程度得以控制。这些悬浮液的冷冻透射电子显微镜图像、浊度和粘度被用于表征这些热响应变化。用p-PNIPAM操纵碳纳米管在水中的分散状态的这种能力可能会使许多生物应用受益，如药物递送、光学传感器和水凝胶。
