用于个人防护装备的聚合物纳米复合纤维的溶液吹丝
Summary
本研究的主要目标是描述一种通过溶液吹丝（SBS）制备具有一致形态的聚合物纤维毡的方案。我们的目标是使用SBS通过在聚合物弹性体基质中加入纳米颗粒来开发用于各种应用的新型，可调谐，柔性聚合物纤维纳米复合材料，包括保护材料。
Abstract
轻型防护装甲系统通常由高模量（>109 MPa）和高强度聚合物纤维组成，用弹性树脂材料（粘合剂）固定到位，形成无纺布单向层压板。虽然在改善高强度纤维的机械性能方面做出了大量努力，但很少有工作来改善粘合剂材料的性能。为了提高这些弹性聚合物粘合剂的性能，使用了一种相对较新且简单的制造工艺，称为溶液吹丝。该技术能够生产平均直径从纳米级到微米级的纤维片或纤维网。为了实现这一目标，在实验室中设计并建造了一种溶液吹丝（SBS）设备，以用聚合物弹性体溶液制造无纺布纤维毡。
本研究采用一种常用的粘结剂材料，即溶解在四氢呋喃中的苯乙烯-丁二烯-苯乙烯嵌段-共聚物，通过添加金属纳米颗粒（NPs），如氧化铁NPs，用硅油封装，从而掺入通过SBS工艺形成的纤维中，生产纳米复合纤维毡。这项工作中描述的方案将讨论SBS过程中涉及的各种关键参数的影响，包括聚合物摩尔质量，热力学适当溶剂的选择，溶液中的聚合物浓度和载气压力，以帮助其他人进行类似的实验，并提供指导优化实验设置的配置。采用扫描电子显微镜（SEM）和能量色散X射线光谱（EDS）对所得无纺布纤维毡的结构完整性和形貌进行了分析.本研究的目的是评估各种实验参数和材料选择对优化SBS纤维毡结构和形貌的影响。
Introduction
目前，许多轻型、弹道、防护装甲系统都是使用高模量和高强度聚合物纤维建造的，例如定向、超高摩尔质量聚乙烯纤维或芳纶，可提供出色的抗弹性1，2。这些纤维与弹性树脂材料（粘合剂）结合使用，该材料可以渗透到长丝水平并将纤维固定在0°/90°配置中，以形成无纺布单向层压板。聚合物弹性体树脂（粘合剂）的百分比不应超过单向层压板总重量的13%，以保持层压板结构的结构完整性和抗弹性能3，4。粘合剂是装甲中非常重要的组成部分，因为它使高强度纤维保持正确定向并紧密包装在每个层压板层3内。在防弹衣应用中通常用作粘合剂的弹性体材料具有非常低的拉伸模量（例如，~23°C 时为 ~17.2 MPa）、低玻璃化转变温度（最好低于 -50 °C）、非常高的断裂伸长率（高达 300%），并且必须表现出优异的粘合性能5。
为了提高这些聚合物弹性体的性能，SBS用于制造纤维弹性体材料，可用作防弹衣应用中的粘合剂。SBS是一种相对较新的多功能技术，允许使用不同的聚合物/溶剂系统并创建不同的最终产品6，7，8，9，10，11，12，13。这种简单的过程涉及将保形纤维快速（静电纺丝速率的10倍）沉积到平面和非平面基材上，以制造包含纳米和微长尺度14，15，16，17，18的纤维片或网。SBS材料在医疗产品、空气过滤器、防护设备、传感器、光学电子和催化剂14、19、20中有许多应用。开发小直径纤维可以大大增加表面积与体积比，这对于多种应用非常重要，尤其是在个人防护设备领域。SBS产生的纤维的直径和形态取决于聚合物的摩尔质量，溶液中的聚合物浓度，溶液的粘度，聚合物溶液的流速，气体压力，工作距离和喷嘴的直径14，15，17。
SBS装置的一个重要特征是由内喷嘴和同心外喷嘴组成的喷嘴。溶解在挥发性溶剂中的聚合物通过内喷嘴泵送，而加压气体流经外喷嘴。从外喷嘴流出的高速气体引起流经内喷嘴的聚合物溶液的剪切。这迫使溶液在离开喷嘴时形成圆锥形。当克服锥体尖端的表面张力时，喷出细小的聚合物溶液流，溶剂迅速蒸发，导致聚合物链聚结并沉积为聚合物纤维。当溶剂蒸发时，纤维结构的形成在很大程度上取决于聚合物摩尔质量和溶液浓度。纤维是通过链缠结形成的，当溶液中的聚合物链开始以称为临界重叠浓度（c*）的浓度重叠时。因此，有必要使用高于所选聚合物/溶剂体系c*的聚合物溶液。此外，实现此目的的简单策略是选择摩尔质量相对较高的聚合物。具有较高摩尔质量的聚合物具有增加的聚合物弛豫时间，这与纤维结构形成的增加直接相关，如文献21中所述。由于SBS中使用的许多参数密切相关，因此这项工作的目标是为开发可调且灵活的聚合物纤维纳米复合材料提供指导，通过在纤维聚合物 – 弹性体基质中加入纳米颗粒，用作防弹衣应用中发现的典型粘合剂材料的替代品。
Protocol
Representative Results
Discussion
本文描述的方法提供了一种通过称为溶液吹丝的相对较新的技术生产聚合物弹性体纳米复合纤维毡的方案。该技术允许在纳米尺度上制造纤维，并且与其他成熟的技术（例如静电纺丝工艺）相比具有几个优点，因为它可以在大气压和室温下进行27。此外，SBS对局部环境变化（温度或湿度）不敏感，不需要刺激性或有毒化学物质，也不需要高电压梯度，这在使用生物系统时是有益?…
Disclosures
The authors have nothing to disclose.
Acknowledgements
作者要感谢Dwight D. Barry先生对溶液吹丝设备的制造做出的重要贡献。Zois Tsinas和Ran Tao分别感谢美国国家标准与技术研究院的资助#70NANB20H007和#70NANB15H112。
Materials
| 45 MM Toolmaker Vise | Tormach Inc. | 32547 | To secure substrate onto the collector |
| ARES-G2 Rheometer | TA Instruments | 401000.501 | Rheometer |
| Branson Ultrasonics M Series – Ultrasonic Cleaning Bath | Fisher Scientific | 15-336-100 | To disperse nanoparticles |
| Cadence Science Micro-Mate Interchangeable Syringe | Fisher Scientific | 14-825-2A | Glass Syringe 5mL in 1/5mL, Luer Lock Tip |
| Chemical hood | Any company | ||
| Corning – Disposable Pasteur Glass Pipette | Sigma Aldrich | CLS7095D5X-200EA | Non-Sterile |
| DWK Life Sciences Wheaton – Glass Scintillation Vial | Fisher Scientific | 03-341-25G | 20 mL with cap |
| FEI Quanta 200 Scanning Electron Microscope (SEM) | FEI | For imaging samples | |
| Iron Oxide Nanopowder/Nanoparticles | US Research Nanomaterials, inc. | US3320 | Fe3O4, 98%, 20-3- nm, Silicon oil Coated |
| KD Scientific Legato 100 Single-Syringe Pump | Sigma Aldrich | Z401358-1EA | Single syringe infusion pump |
| Master Airbrush – Model S68 | TCP Global | MAS S68 | Nozzle/needle diameter: 0.35 mm |
| Mettler Toledo AB265-S/FACT Scale | Cole-Parmer Scientific | EW-11333-14 | For weighing polymer and Nanoparticles |
| N2 Gas Regulator | Any company | ||
| Nanoenclosure | Any company | ||
| Optical Microscopy Glass Slides | Fisher Scientific | 12-550-A3 | Used as a substrate for fiber mat deposition |
| OSP Slotted Bob, 33 mm | TA Instruments | 402796.902 | Bob, upper geometry |
| OSP Slotted Double Gap Cup, 34 mm | TA Instruments | 402782.901 | Double wall cup, lower geometry |
| Oxford BenchMate Digital Vortex Mixer | Pipette | VM-D | Rated up to 4,200 rpm, for mixing solutions |
| Oxford Benchmate Tube Roller | Pipette | OTR-24DR | Sample mixer/rotator |
| Polystyrene-block-polybutadiene-block-polystyrene | Sigma Aldrich | 432490-1KG | styrene 30 wt. %, Mw ~ 185,000 g/mol |
| SEM Pin Stub Specimen Mount | Ted Pella Inc. | 16119 | 18 mm diameter x 8 mm height |
| Spatula | VWR | 82027-532 | To load test materials |
| Tetrahydrofuran (THF) | Fisher Scientific | T425-1 | solvent, HPLC grade |
| TRIOS | TA Instruments | v4.3.1.39215 | Rheometer software |
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