通过结晶驱动生物降解块共聚物的自组装合成单分散圆柱状纳米粒子
Summary
结晶驱动自组装 (CDSA) 显示了制造窄长度分布的圆柱形纳米结构的独特能力。演示了β-卡罗酮的有机环开聚合以及甲基丙烯酸酯和N、N-二甲基丙烯酰胺的后续链延伸。概述了一种可生产长度达 500 nm 的单分散圆柱体的活 CDSA 协议。
Abstract
单分散圆柱形云母的生产是聚合物化学中的一大挑战。大多数由二块共聚物形成的圆柱形结构是由三种技术之一产生的:薄膜补液、溶剂切换或聚合诱导自组装,只生产柔性多分散圆柱体。结晶驱动自组装 (CDSA) 是一种方法,通过稳定低曲率结构,从而产生具有这些特性的圆柱体。然而,大多数核心形成块形成的活聚合技术不是微不足道的过程,CDSA过程如果执行不当,可能会产生不令人满意的结果。这里显示了从简单试剂中合成的圆柱形纳米粒子。介绍了在用磷酸二苯催化的β-卡洛尔酮的环开聚合之前试剂的干燥和纯化。然后,该聚合物通过甲基丙烯酸酯 (MMA) 延伸链,然后使用可逆添加-碎片链转移 (RAFT) 聚合,然后使用 N、N-二甲基丙烯酰胺 (DMA) 进行聚合,从而提供可进行 CDSA 的三块共聚物。乙醇。概述了活CDSA工艺,其结果产生长度达500nm的圆柱形纳米粒子,长度分散度低至1.05。预计这些协议将允许其他人在未来生产圆柱形纳米结构并提升CDSA领域。
Introduction
一维(1D)纳米结构,如圆柱体、纤维和管材,在各个领域越来越受到关注。其中,它们在聚合物科学中的受欢迎程度归功于其丰富的各种特性。例如,耿等人证明,与球形模型相比,微体细胞在啮齿类模型的血液中停留时间增加了十倍,Won等人发现聚丁二烯-b-聚类(环氧)纤维分散体显示,在风变测量1、2期间,当核心交联时,存储模量增加两个数量级。有趣的是,许多这些系统是通过块共聚物的自组装合成的,无论是通过更传统的溶剂转换和薄膜补液3方法,还是更先进的方法,如聚合诱导自组装和结晶驱动自组装(CDSA)4,5。每种技术都有其自身的优点,但是,只有 CDSA 才能产生具有均匀且可控长度分布的刚性颗粒。
Gilroy等人的开创性工作在六烷中形成了长多铁硅烷-b-聚二甲基硅氧烷(PFS-PDMS)气缸,使用温和的声波时,具有低轮廓长度分散度的极短圆柱体(Ln)。在普通溶剂中加入预定质量的二聚基共聚链后,合成了不同长度、Ln低至1.03的圆柱体。Manners小组的进一步工作强调了PFS系统的高度控制,该系统可用于形成极其复杂和等级的结构:块状协式云母、围巾形和哑铃云母,仅举几例。8.在这些演示之后,研究人员调查了CDSA的其他功能性系统,包括:半结晶商品聚合物(聚乙烯、聚丙酮、聚乳酸)9、10 ,11,12,13 和导电聚合物 (聚(3-六基硫磷), 聚苯乙烯) 14,15。配备这种可快速、高效地组装的二聚物共聚系统工具箱,研究人员近年来进行了更多的应用驱动型研究。 Jin等人在数百纳米的聚硫芬块共聚物中证明了兴奋扩散长度,我们小组展示了含有圆柱形结构的聚物(β-caprolactone)(PCL)的凝胶的形成。 17.
虽然这是一个强大的技术,CDSA确实有其局限性。块共聚物必须具有半结晶成分,以及低分散值和高端组保真度;低阶块污染物可能导致颗粒聚集或诱发形态变化18、19。由于这些限制,使用活聚合。然而,要获得具有上述特性的聚合物,需要大量的试剂净化、干燥程序和无水/无氧环境。已经尝试设计克服这一点的系统。例如,PFS块共聚物已经形成使用点击化学耦合聚合物链一起20。虽然生成的圆柱形纳米粒子具有示范性,但块共聚物通常通过准备尺寸排除色谱进行纯化,PFS的合成仍需要使用活的电子化聚合。我们小组最近实现了PCL的活CDSA,其成功围绕着使用活有机碱催化环开聚合(ROP)和可逆添加-碎片链转移(RAFT)聚合10。虽然这种方法更简单,但仍需要活的聚合。
随着该领域正朝着更多应用驱动的研究方向发展,并且由于与活聚合相关的问题,人们认为聚合物合成和自组装协议的大纲将有利于未来的科学工作。因此,在本手稿中,概述了PCL-b-PMMA-b-PDMA共聚物的完整合成和自组装。干燥技术将在β-caprolactone的有机化ROP的上下文中突出显示,并概述MMA和DMA随后的RAFT聚合。最后,将提出乙醇中这种聚合物的活CDSA方案,并批评由于实验技术落后而出现特征数据中的常见错误。
Protocol
Representative Results
Discussion
三块共聚PCL 50-PMMA10-PDMA200的合成和活CDSA已经概述。尽管需要严格的条件,但 β-caprolactone 的环开聚合为聚合物提供了优异的特性,使 MMA 和 DMA 的链延伸得以成功。这些聚合物在自播种中取得了成功,获得了圆柱形云母的纯相,这些圆柱形云母被声波化成LN 98nm的种子颗粒中。通过简单添加单体,以受控方式生产平均长度可达 495 nm 的气缸。在这种情况下,在二块共聚?…
Disclosures
The authors have nothing to disclose.
Acknowledgements
没有确认。
Materials
| 2,2'-azobisisobutyrnitrile | Sigma Aldrich | ||
| 250 mL ampoule | |||
| 250 mL two neck RBF | |||
| Ampoule (25 mL) | |||
| B19 tap | |||
| B24 stopper | |||
| Basic Alumina | Fluka | ||
| Buchner Flask | |||
| Buchner Funnel | |||
| Caclium Hydride | |||
| Cannulae | |||
| caprolactone | Arcos Organics | ||
| Chain Transfer Agent | Made in House | ||
| Conical Flask (multiple sizes) | |||
| Dessicator | |||
| Diethyl Ether | Merck | ||
| Dioxane | Fisher | ||
| diphenylphosphate | Sigma Aldrich | ||
| Distillation Condenser | |||
| Ethanol | Fisher | ||
| Filter Paper (multiple sizes) | |||
| Gel Permeation Chrmoatography Instrument | Agilent Technologies Infinity 1260 II | Running DMF at 50 °C | |
| Glovebox | Mbraun, Unilab | ||
| Hotplate | IKA, RCT basic | ||
| Mercury Thermometer | |||
| Methyl Methacrylate | Sigma Aldrich | ||
| Molecular seives | Fisher | MS/1030/53 | |
| N,N-dimethyl acrylamide | Sigma Aldrich | ||
| NMR spectrometer | Bruker 400 MHz | ||
| Phosphorus pentoxide | Sigma Aldrich | ||
| RBF (multiple sizes) | |||
| Schlenk Cap (B24) | |||
| Schlenk Flask (250 mL) | |||
| Schlenk Line | |||
| Sonication Probe | Bandelin Sonoplus | ||
| Suba Seal (multiple sizes) | |||
| TEM grids | EmResolutions, Formvar/carbon film 300 mesh copper | ||
| THF | Merck | ||
| three neck adaptor | |||
| Toluene | Fisher | ||
| Transmission Electron Microscope | Jeol 2100 |
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