Production and Investigation of Cholesteric Liquid Crystal-Polymer Fibers by Electrospinning Method

Yıl 2023, Cilt: 13 Sayı: 4, 1661 - 1680, 15.12.2023

Mervenur Kılıç , Mustafa Can , Nejmettin Avcı , Atilla Eren Mamuk

https://doi.org/10.31466/kfbd.1330612

Öz

It is well-known that liquid crystals are widely used in applications such as display technology, sensor, elastic circuit component, and light-modulator. Cholesteric liquid crystals come into prominence with their selective transmittance of light. In the study, cholesteric liquid crystals - polymer fiber composites are produced and investigated using single-needle electrospinning for the first time. In this sense, in the beginning, cholesteric liquid crystals with 470 nm, 550 nm, and 640 nm spiral pitches which can reflect blue, green, and red lights, respectively are prepared. It is used E-7 as host nematic mesophase and R 5011 with high twisting power as a chiral dopant material. It was shown by UV-VIS spectrophotometer measurements that the cholesterics have approximately the desired spiral pitch lengths. It is also observed that the the cholesterics have oily-streak patterns, which is a characteristic texture for cholesterics. In addition, the cholesterics are mixed with polyacrylonitrile and the mixture is solved into dimethylformamide. Moreover, liquid crystal-polymer composite fibers are produced by spinning the solutions using single-needle electrospinning under spinning voltages of 16 kV, 18 kV, 20 kV, 22 kV and 24 kV. The existence of liquid crystals inside the fiber is proved by carrying out optical and structural analyses. In the imaging with a polarized optical microscope, irradiances were observed along the fibers between the cross polarizers. These irradiances indicated that liquid crystals have settled along the fiber. Also, it studies on a variance of the fiber structure depending on liquid crystal dopant and production parameters with structural analyses. For the all cholesteric samples, spherical bead structures were detected along the spun fibers at low spinning voltages, while in the fibers at higher spinning voltages the bead structures were observed very rarely. Infrared spectroscopy analysis of the fibers showed the presence of liquid crystals in the fiber structures with peaks at the same wave numbers as the vibration peaks exhibited by liquid crystals.

Anahtar Kelimeler

Cholesteric liquid crystals, electrospinning, fiber

Proje Numarası

1919B012112581

Kolesterik Sıvı Kristal - Polimer Liflerinin Elektro-eğirme Yöntemi ile Üretilmesi ve İncelenmesi

Öz

Sıvı kristallerin ekran teknolojisi, sensör, esnek devre elamanları, ışık modülatörleri gibi uygulamalarda kullanılabildiği bilinmektedir. Kolesterik mezofaz sıvı kristaller ışığın seçici geçirgenlik özelliği ile ön plana çıkmaktalardır. Bu çalışmada, ilk defa tek-iğneli elektro-eğirme kullanılarak kolesterik sıvı kristaller-polimer kompozit liflerinin üretilmiş ve incelenmiştir. Bu bağlamda ilk olarak, mavi, yeşil ve kırmızı renkte ışığı yansıtabilecek sırasıyla 470 nm, 550 nm ve 640 nm spiral adım uzunluklarına sahip kolesterik sıvı kristaller hazırlanmıştır. Konak nematik mezofaz olarak E-7 ve yüksek burma gücüne sahip R-5011 kiral katkı maddesi kullanılmıştır. Bu kolesteriklerin yaklaşık istenilen adım uzunluklarına sahip oldukları UV-VIS spektrofotometre ölçümleri ile gösterilmiştir. Ayrıca, hazırlanan kolesteriklerin karakteristik bir tekstür olan oily-streak desenlere sahip olduğu görülmektedir. Bu kolesterikler poliakrilonitril ile karıştırılarak dimetilformamid içerisinde çözdürülmüştür. Bu çözeltiler tek-iğneli elektro-eğirme sistemi ile 16 kV, 18 kV, 20 kV, 22 kV ve 24 kV uygulama voltajları altında eğirilerek sıvı kristal polimer kompozit lifleri haline getirilmişlerdir. Eğirilen liflere katkılanan kolesterik sıvı kristallerin varlığı optik ve yapısal analizler geçekleştirilerek belirlenmiştir. Polarize optik mikroskop ile yapılan görüntülemelerde çapraz polarizörler arasındaki lifler boyunca parlamalar gözlenmiştir. Bu parlamalar lif boyunca sıvı kristallerin yerleştiğini göstermektedir. Ayrıca, yapısal analiz sonucu her bir lifte üretim parametreleri ve katkı maddelerine göre lif yapısının değişimi üzerine çalışma yapılmıştır. Tüm kolesterik örnekleri için düşük uygulama voltajlarında eğirilen lifler boyunca uzanan küresel boncuk yapılar tespit edilmişken daha yüksek uygulama voltajlarında eğirilen liflerde boncuk yapılar oldukça seyrek gözlenmiştir. Kızılötesi spektroskopisi analizleri sonucu liflerin sıvı kristallerin sergilediği titreşim pikleri ile aynı dalga sayılarında pikler vermesi lif yapılarında sıvı kristallerin varlığını göstermiştir.

Anahtar Kelimeler

Kolesterik sıvı kristaller, elektro-eğirme, lif

Destekleyen Kurum

TÜBİTAK (2209-A - Üniversite Öğrencileri Araştırma Projeleri Destekleme Programı)

Proje Numarası

1919B012112581

Teşekkür

Bu çalışma 2209-A - Üniversite Öğrencileri Araştırma Projeleri Destekleme Programı tarafından desteklenmiştir. Malzeme üretimi ve ölçümlerin geçekleştirilmesinde Muğla Sıtkı Koçman Üniversitesi bünyesinde bulunan Araştırma Laboratuvarları Merkezi’ne ve Moleküler Nano Malzeme Laboratuvarı’na, ayrıca, Dr. Çiğdem Elif Demirci’ye verdikleri teknik destekten dolayı teşekkür ederiz.

Kaynakça

• Bagiński, M., Tupikowska, M., González‐Rubio, G., Wójcik, M., & Lewandowski, W. (2020). Shaping Liquid Crystals with Gold Nanoparticles: Helical Assemblies with Tunable and Hierarchical Structures Via Thin‐Film Cooperative Interactions. Advanced Materials, 32(1), 1904581. https://doi.org/10.1002/adma.201904581
• Buyuktanir, E. A., Frey, M. W., & West, J. L. (2010). Self-assembled, optically responsive nematic liquid crystal/polymer core-shell fibers: Formation and characterization. Polymer, 51(21), 4823–4830. https://doi.org/10.1016/j.polymer.2010.08.011
• Büyüktanir, E. A., Gheorghiu, N., West, J. L., Mitrokhin, M., Holter, B., & Glushchenko, A. (2006). Field-induced polymer wall formation in a bistable smectic-A liquid crystal display. Applied Physics Letters, 89(3), 031101. https://doi.org/10.1063/1.2221887
• Cramariuc, B., Cramariuc, R., Scarlet, R., Manea, L. R., Lupu, I. G., & Cramariuc, O. (2013). Fiber diameter in electrospinning process. Journal of Electrostatics, 71(3), 189–198. https://doi.org/10.1016/j.elstat.2012.12.018
• Demus, D., Goodby, J., Gray, G. W., Spiess, H. ‐W., & Vill, V. (1998). Handbook of Liquid Crystals. In Handbook of Liquid Crystals. https://doi.org/10.1002/9783527620760
• Dierking, I. (2003). Textures of Liquid Crystals. In Textures of Liquid Crystals. https://doi.org/10.1002/3527602054
• Enz, E., & Lagerwall, J. (2010). Electrospun microfibres with temperature sensitive iridescence from encapsulated cholesteric liquid crystal. Journal of Materials Chemistry, 20(33), 6866. https://doi.org/10.1039/c0jm01223h
• Finkelmann, H., Kim, S. T., Muñoz, A., Palffy-Muhoray, P., & Taheri, B. (2001). Tunable Mirrorless Lasing in Cholesteric Liquid Crystalline Elastomers. Advanced Materials, 13(14), 1069–1072. https://doi.org/10.1002/1521-4095(200107)13:14<1069::AID-ADMA1069>3.0.CO;2-6
• Fong, H., Chun, I., & Reneker, D. . (1999). Beaded nanofibers formed during electrospinning. Polymer, 40(16), 4585–4592. https://doi.org/10.1016/S0032-3861(99)00068-3
• Froyen, A. A. F., Debije, M. G., & Schenning, A. P. H. J. (2022). Polymer Dispersed Cholesteric Liquid Crystal Mixtures for Optical Time–Temperature Integrators. Advanced Optical Materials, 10(22). https://doi.org/10.1002/adom.202201648
• Guan, Y., Zhang, L., Li, M., West, J. L., & Fu, S. (2018). Preparation of temperature-response fibers with cholesteric liquid crystal dispersion. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 546(March), 212–220. https://doi.org/10.1016/j.colsurfa.2018.03.011
• Guan, Y., Zhang, L., Wang, D., West, J. L., & Fu, S. (2018). Preparation of thermochromic liquid crystal microcapsules for intelligent functional fiber. Materials & Design, 147, 28–34. https://doi.org/10.1016/j.matdes.2018.03.030
• Jangizehi, A., Schmid, F., Besenius, P., Kremer, K., & Seiffert, S. (2020). Defects and defect engineering in Soft Matter. Soft Matter, 16(48), 10809–10859. https://doi.org/10.1039/d0sm01371d
• Kim, M. S., Mishra, R. K., Manda, R., Murali, G., Kim, T. H., Lee, M. H., Yun, M., Kundu, S., Kim, B. S., & Lee, S. H. (2017). Reduced graphene oxide (RGO) enriched polymer network for highly-enhanced electro-optic performance of a liquid crystalline blue phase. RSC Advances, 7(27), 16650–16654. https://doi.org/10.1039/c6ra28465e
• Lagerwall, J. P. F., & Scalia, G. (2012). A new era for liquid crystal research: Applications of liquid crystals in soft matter nano-, bio- and microtechnology. Current Applied Physics, 12(6), 1387–1412. https://doi.org/10.1016/j.cap.2012.03.019
• Li, M.-H., & Keller, P. (2006). Artificial muscles based on liquid crystal elastomers. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 364(1847), 2763–2777. https://doi.org/10.1098/rsta.2006.1853
• Lin, J.-D., Chen, C.-P., Chen, L.-J., Chuang, Y.-C., Huang, S.-Y., & Lee, C.-R. (2016). Morphological appearances and photo-controllable coloration of dye-doped cholesteric liquid crystal/polymer coaxial microfibers fabricated by coaxial electrospinning technique. Optics Express, 24(3), 3112. https://doi.org/10.1364/OE.24.003112
• Mashchenko, V. I., Goponenko, A. V., Udra, C. A., Filyakin, A. M., & Gerasimov, V. I. (2001). Use of polyacrylonitrile as promising material for matrix of liquid crystal composite. In V. V. Belyaev & I. N. Kompanets (Eds.), Advanced Display Technologies: Basic Studies of Problems in Information Display (FLOWERS 2000) (Vol. 4511, Issue Flowers 2000, pp. 127–132). https://doi.org/10.1117/12.431273
• Nguyen, J., Stwodah, R. M., Vasey, C. L., Rabatin, B. E., Atherton, B., D’Angelo, P. A., Swana, K. W., & Tang, C. (2020). Thermochromic fibers via electrospinning. Polymers, 12(4). https://doi.org/10.3390/POLYM12040842
• Özden, P., Mamuk, A. E., & Avcı, N. (2019). Investigation of the viscoelastic properties of 4-propoxy-biphenyl-4-carbonitrile. Liquid Crystals, 46(15), 2190–2200. https://doi.org/10.1080/02678292.2019.1614236
• Reneker, D. H., & Chun, I. (1996). Nanometre diameter fibres of polymer, produced by electrospinning. Nanotechnology, 7(3), 216–223. https://doi.org/10.1088/0957-4484/7/3/009
• Reyes, C. G., Sharma, A., & Lagerwall, J. P. F. (2016). Non-electronic gas sensors from electrospun mats of liquid crystal core fibres for detecting volatile organic compounds at room temperature. Liquid Crystals, 43(13–15), 1986–2001. https://doi.org/10.1080/02678292.2016.1212287
• Salim, N. V., Jin, X., & Razal, J. M. (2019). Polyacrylonitrile/liquid crystalline graphene oxide composite fibers – Towards high performance carbon fiber precursors. Composites Science and Technology, 182(December 2018), 107781. https://doi.org/10.1016/j.compscitech.2019.107781
• Sharma, A., & Lagerwall, J. (2018). Electrospun Composite Liquid Crystal Elastomer Fibers. Materials, 11(3), 393. https://doi.org/10.3390/ma11030393
• Stephenson, S. W., Johnson, D. M., Kilburn, J. I., Mi, X.-D., Rankin, C. M., & Capurso, R. G. (2004). Development of a Flexible Electronic Display Using Photographic Technology. SID Symposium Digest of Technical Papers, 35(1), 774. https://doi.org/10.1889/1.1821394
• Thum, M. D., Ratchford, D. C., Casalini, R., Wynne, J. H., & Lundin, J. G. (2021). Azobenzene-Doped Liquid Crystals in Electrospun Nanofibrous Mats for Photochemical Phase Control. ACS Applied Nano Materials, 4(1), 297–304. https://doi.org/10.1021/acsanm.0c02654
• Vats, S., Honaker, L. W., Basoli, F., & Lagerwall, J. P. F. (2022). Combining responsiveness and durability in liquid crystal-functionalised electrospun fibres with crosslinked sheath. Liquid Crystals, 49(5), 690–698. https://doi.org/10.1080/02678292.2021.2005166
• Wang, J., Jákli, A., & West, J. L. (2016). Morphology Tuning of Electrospun Liquid Crystal/Polymer Fibers. ChemPhysChem, 17(19), 3080–3085. https://doi.org/10.1002/cphc.201600430
• Wang, J., Jákli, A., & West, J. L. (2018). Liquid crystal/polymer fiber mats as sensitive chemical sensors. Journal of Molecular Liquids, 267, 490–495. https://doi.org/10.1016/j.molliq.2018.01.051
• Wei, Q., Lv, P., Zhang, Y., Zhang, J., Qin, Z., De Haan, L. T., Chen, J., Wang, D., Xu, B. Bin, Broer, D. J., Zhou, G., Ding, L., & Zhao, W. (2022). Facile Stratification-Enabled Emergent Hyper-Reflectivity in Cholesteric Liquid Crystals. ACS Applied Materials and Interfaces. https://doi.org/10.1021/acsami.2c16938
• Williams, M. W., Wimberly, J. A., Stwodah, R. M., Nguyen, J., D’Angelo, P. A., & Tang, C. (2023). Temperature-Responsive Structurally Colored Fibers via Blend Electrospinning. ACS Applied Polymer Materials, 5(4), 3065–3078. https://doi.org/10.1021/acsapm.3c00222
• Zappone, B., Mamuk, A. E., Gryn, I., Arima, V., Zizzari, A., Bartolino, R., Lacaze, E., & Petschek, R. (2020). Analogy between periodic patterns in thin smectic liquid crystal films and the intermediate state of superconductors. Proceedings of the National Academy of Sciences, 117(30), 17643–17649. https://doi.org/10.1073/pnas.2000849117
• Zhang, W. X., Wang, Y. Z., & Sun, C. F. (2007). Characterization on oxidative stabilization of polyacrylonitrile nanofibers prepared by electrospinning. Journal of Polymer Research, 14(6), 467–474. https://doi.org/10.1007/s10965-007-9130-x
• Zhang, Z., Bolshakov, A., Han, J., Zhu, J., & Yang, K. L. (2022). Electrospun Core-Sheath Fibers with a Uniformly Aligned Polymer Network Liquid Crystal (PNLC). ACS Applied Materials and Interfaces. https://doi.org/10.1021/acsami.2c23065