水包油之乳液(Oil-in-water(O/W) emulsion)通常是透過界面活型劑或乳化劑來製備，不過由於時代的進步以及環保意識的提升，消費者更喜歡天然的物質，因此本研究將乳液中的界面活性劑或乳化劑替換成奈米結晶纖維(Cellulose Nanocrystals, CNCs)，並使用超音波破碎機進行乳化，形成皮克林乳液(Pickering emulsion)。本研究採用油/水體積比為1:4來製備CNCs皮克林乳液，乳液液滴的平均粒徑為1.59m，將乳液脫水可形成乳液乾粉及乳液紙膜，擴大乳液的用途範圍。不過在冷凍乾燥的過程中乳液液滴容易被破壞，導致油滴洩出，為改善此一現象，本研究透過單寧酸(Tannic acid, TA)與水溶性之甲基纖維素(Methylcellulose, MC)的交聯作用在CNCs皮克林乳液的表面形成不溶水的膜，覆膜的乳液液滴平均粒徑為2.75m。此外，亦利用單寧酸易與金屬離子螯合形成複合物的性質，在CNCs皮克林乳液液滴的表面與三價鐵離子(Ferric ion, FeⅢ)反應來包覆液滴，所形成的液滴平均粒徑為2.69m。兩種方法皆有保護乾乳液的效果，並且有利於再次均勻分散於水中。
此外，提高CNCs溶液濃度至1 wt%製備成較高濃度的CNCs皮克林乳液，經乾燥後可形成乳液紙膜。研究發現在5 mL的乳液中含有100 mg的olive oil所製成的乳液紙膜最為穩定，其中所含的olive oil占總重量的65.6 wt%。

Oil-in-water (O/W) emulsions are usually prepared by using synthetic surfactants or emulsifiers. In recent years, consumers prefer to use green and sustainable products. In this work, we replaced the synthetic surfactant or emulsifier with cellulose nanocrystals (CNCs) to emulsify plant derived cosmetic oil and essential oil for the preparation of dry oil powder and free-standing emulsion paper. Oil-to-water volume ratio of 1:4, CNCs concentration of 0.3 w% and NaCl concentration of 20 mM were employed to CNCs-based Pickering emulsion via ultrasonication. The average size of the CNCs Pickering emulsion droplets was 1.59m. In order to stabilize the emulsion droplets from leaking, tannic acid (TA) and water-soluble methylcellulose (MC) were employed to form a water-insoluble coating on the surface Pickering emulsion droplets. Once coated with MC and cross-linked with TA, the averaged size of the droplets increased to 2.75 m. In addition, tannic acid was also employed to chelate with ferric ion (FeⅢ) to form TA-Fe(III) film on the surface of CNCs Pickering emulsion droplets. The microencapsulated oil could be well preserved from leaking during the process of drying the emulsion. The dry oil emulsion could be easily re-dispersed in water when microencapsulated in either TA-Fe (III) or MC-TA coatings. Moreover, increased the concentration of CNCs solution to 1 wt%, the free-standing emulsion paper could be obtained after air-drying the O/W emulsion. The very stable dry emulsion paper could be made of 100 mg of oil in 5 mL emulsion and the oil content in the dry paper could
be as high as 65.6 wt%.

[1] Y. Chevalier and M.-A. Bolzinger, "Emulsions stabilized with solid nanoparticles: Pickering emulsions," Colloids and Surfaces A: Physicochemical
and Engineering Aspects, vol. 439, pp. 23-34, 2013.
[2] I. A. Sacui et al., "Comparison of the properties of cellulose nanocrystals and cellulose nanofibrils isolated from bacteria, tunicate, and wood processed using acid, enzymatic, mechanical, and oxidative methods," ACS applied materials
interfaces, vol. 6, no. 9, pp. 6127-6138, 2014.
[3] Y. Zhang, V. Karimkhani, B. T. Makowski, G. Samaranayake, and S. J. Rowan, "Nanoemulsions and nanolatexes stabilized by hydrophobically functionalized cellulose nanocrystals," Macromolecules, vol. 50, no. 16, pp. 6032-6042, 2017.
[4] K.-Y. Lee, Y. Aitomäki, L. A. Berglund, K. Oksman, and A. Bismarck, "On the use of nanocellulose as reinforcement in polymer matrix composites,"
Composites Science Technology, vol. 105, pp. 15-27, 2014.
[5] D. Bondeson and K. Oksman, "Polylactic acid/cellulose whisker nanocomposites modified by polyvinyl alcohol," Composites Part A: Applied
Science Manufacturing, vol. 38, no. 12, pp. 2486-2492, 2007.
[6] A. J. Uddin, J. Araki, and Y. Gotoh, "Characterization of the poly (vinyl alcohol)/cellulose whisker gel spun fibers," Composites Part A: Applied Science
Manufacturing, vol. 42, no. 7, pp. 741-747, 2011.
[7] C. Bruel, Q. Beuguel, J. R. Tavares, P. J. Carreau, and M.-C. Heuzey, "The apparent structural hydrophobicity of cellulose nanocrystals," J-FOR The Journal of Science Technology for Forest Products Processes, vol. 7, no. 4, pp.
13-23, 2018.
[8] C. Bruel, J. R. Tavares, P. J. Carreau, and M.-C. Heuzey, "The structural amphiphilicity of cellulose nanocrystals characterized from their cohesion
parameters," Carbohydrate polymers, vol. 205, pp. 184-191, 2019.
[9] R. Mezzenga and S. Ulrich, "Spray-dried oil powder with ultrahigh oil content,"
Langmuir, vol. 26, no. 22, pp. 16658-16661, 2010.
[10] Z. Hu, H. S. Marway, H. Kasem, R. Pelton, and E. D. Cranston, "Dried and Redispersible Cellulose Nanocrystal Pickering Emulsions," ACS Macro Letters,
vol. 5, no. 2, pp. 185-189, 2016.
[11] L. Valencia, E. M. Nomena, A. P. Mathew, and K. P. Velikov, "Biobased Cellulose Nanofibril–Oil Composite Films for Active Edible Barriers," ACS
applied materials interfaces, vol. 11, no. 17, pp. 16040-16047, 2019.
[12] C. Salas, T. Nypelö, C. Rodriguez-Abreu, C. Carrillo, and O. J. Rojas, "Nanocellulose properties and applications in colloids and interfaces," Current Opinion in Colloid & Interface Science, vol. 19, no. 5, pp. 383-396, 2014.
[13] R. Gilbert and J. Kadla, "Polysaccharides—cellulose," in Biopolymers from
renewable resources: Springer, 1998, pp. 47-95.
[14] M. Iguchi, S. Yamanaka, and A. Budhiono, "Bacterial cellulose—a masterpiece of nature's arts," Journal of materials science, vol. 35, no. 2, pp. 261-270, 2000.
[15] H. Ullah, F. Wahid, H. A. Santos, and T. Khan, "Advances in biomedical and pharmaceutical applications of functional bacterial cellulose-based nanocomposites," Carbohydrate polymers, vol. 150, pp. 330-352, 2016.
[16] Y. H. Kim, S. Park, K. Won, H. J. Kim, and S. H. Lee, "Bacterial cellulose–carbon nanotube composite as a biocompatible electrode for the direct electron transfer of glucose oxidase," Journal of Chemical Technology Biotechnology,
vol. 88, no. 6, pp. 1067-1070, 2013.
[17] Y. Habibi, L. A. Lucia, and O. J. Rojas, "Cellulose nanocrystals: chemistry, self-assembly, and applications," Chem Rev, vol. 110, no. 6, pp. 3479-3500,
2010.
[18] S. S. Dalli, B. K. Uprety, M. Samavi, R. Singh, and S. K. Rakshit, "Nanocrystalline Cellulose: Production and Applications," in Exploring the
Realms of Nature for Nanosynthesis: Springer, 2018, pp. 385-405.
[19] E. Fortunati et al., "Multifunctional bionanocomposite films of poly (lactic acid), cellulose nanocrystals and silver nanoparticles," Carbohydrate polymers,
vol. 87, no. 2, pp. 1596-1605, 2012.
[20] M. Börjesson and G. Westman, "Crystalline Nanocellulose — Preparation, Modification, and Properties," in Cellulose - Fundamental Aspects and Current
Trends, 2015.
[21] M. Islam, L. Chen, J. Sisler, and K. Tam, "Cellulose nanocrystal (CNC)–inorganic hybrid systems: synthesis, properties and applications," Journal of
Materials Chemistry B, vol. 6, no. 6, pp. 864-883, 2018.
[22] S. N. Molnes, K. G. Paso, S. Strand, and K. Syverud, "The effects of pH, time and temperature on the stability and viscosity of cellulose nanocrystal (CNC) dispersions: implications for use in enhanced oil recovery," Cellulose, vol. 24,
no. 10, pp. 4479-4491, 2017.
[23] Y. Boluk, R. Lahiji, L. Zhao, and M. T. McDermott, "Suspension viscosities and shape parameter of cellulose nanocrystals (CNC)," Colloids Surfaces A:
Physicochemical Engineering Aspects, vol. 377, no. 1-3, pp. 297-303, 2011.
[24] S. Shafiei-Sabet, W. Hamad, and S. Hatzikiriakos, "Ionic strength effects on the microstructure and shear rheology of cellulose nanocrystal suspensions,"
Cellulose, vol. 21, no. 5, pp. 3347-3359, 2014.
[25] R. Rusli, K. Shanmuganathan, S. J. Rowan, C. Weder, and S. J. Eichhorn, "Stress Transfer in Cellulose Nanowhisker Composites Influence of Whisker Aspect Ratio and Surface Charge," Biomacromolecules, vol. 12, no. 4, pp.
1363-1369, 2011.
[26] Z. Hu, R. M. Berry, R. Pelton, E. D. Cranston, and Engineering, "One-pot water-based hydrophobic surface modification of cellulose nanocrystals using plant polyphenols," ACS Sustainable Chemistry & Engineering, vol. 5, no. 6,
pp. 5018-5026, 2017.
[27] J. George, S. Sabapathi, and applications, "Cellulose nanocrystals: synthesis, functional properties, and applications," Nanotechnology, science, vol. 8, p. 45,
2015.
[28] R. A. Chowdhury, C. Clarkson, and J. Youngblood, "Continuous roll-to-roll fabrication of transparent cellulose nanocrystal (CNC) coatings with controlled
anisotropy," Cellulose, vol. 25, no. 3, pp. 1769-1781, 2018.
[29] L. Lewis, M. Derakhshandeh, S. G. Hatzikiriakos, W. Y. Hamad, and M. J. MacLachlan, "Hydrothermal gelation of aqueous cellulose nanocrystal
suspensions," Biomacromolecules, vol. 17, no. 8, pp. 2747-2754, 2016.
[30] S. Suenaga, M. Osada, and Engineering, "Self-sustaining cellulose nanofiber hydrogel produced by hydrothermal gelation without additives," ACS
Biomaterials Science & Engineering, vol. 4, no. 5, pp. 1536-1545, 2018.
[31] E. Abraham, D. E. Weber, S. Sharon, S. Lapidot, and O. Shoseyov, "Multifunctional cellulosic scaffolds from modified cellulose nanocrystals,"
ACS applied materials interfaces, vol. 9, no. 3, pp. 2010-2015, 2017.
[32] C. G. Otoni et al., "Recent advances on edible films based on fruits and vegetables—a review," Comprehensive Reviews in Food Science Food Safety,
vol. 16, no. 5, pp. 1151-1169, 2017.
[33] X. Li, J. Li, J. Gong, Y. Kuang, L. Mo, and T. Song, "Cellulose nanocrystals (CNCs) with different crystalline allomorph for oil in water Pickering
emulsions," Carbohydrate polymers, vol. 183, pp. 303-310, 2018.
[34] İ. Gülçin, Z. Huyut, M. Elmastaş, and H. Y. Aboul-Enein, "Radical scavenging and antioxidant activity of tannic acid," Arabian Journal of Chemistry, vol. 3,
no. 1, pp. 43-53, 2010.
[35] K.-T. Chung, T. Y. Wong, C.-I. Wei, Y.-W. Huang, and Y. Lin, "Tannins and human health: a review," Critical reviews in food science nutrition, vol. 38, no.
6, pp. 421-464, 1998.
[36] T. F. Martínez, T. A. McAllister, Y. Wang, and T. Reuter, "Effects of tannic acid and quebracho tannins on in vitro ruminal fermentation of wheat and corn grain," Journal of the Science of Food Agriculture, vol. 86, no. 8, pp. 1244-
1256, 2006.
[37] H. Winkelmann, E. Badisch, S. Ilo, and S. Eglsäer, "Corrosion behaviour of tool steels in tannic acids," Materials corrosion, vol. 60, no. 3, pp. 192-198,
2009.
[38] D. Slawinska, J. Slawinski, K. Polewski, and W. Pukacki, "Chemiluminescence in the peroxidation of tannic acid," Photochemistry Photobiology, vol. 30, no.
1, pp. 71-80, 1979.
[39] H. Mollenhauer and D. Morré, "Some unusual staining properties of tannic acid
in plants," Histochemistry, vol. 88, no. 1, pp. 17-22, 1987.
[40] Z. Fu and R. Chen, "Study of Complexes of Tannic Acid with Fe(III) and
Fe(II)," J Anal Methods Chem, vol. 2019, p. 3894571, 2019.
[41] Ş. Sungur and A. Uzar, "Investigation of complexes tannic acid and myricetin with Fe (III)," Spectrochimica Acta Part A: Molecular Biomolecular
Spectroscopy, vol. 69, no. 1, pp. 225-229, 2008.
[42] H. Ejima et al., "One-step assembly of coordination complexes for versatile
film and particle engineering," Science, vol. 341, no. 6142, pp. 154-157, 2013.
[43] V. Rubentheren, T. A. Ward, C. Y. Chee, and P. Nair, "Physical and chemical reinforcement of chitosan film using nanocrystalline cellulose and tannic acid,"
Cellulose, vol. 22, no. 4, pp. 2529-2541, 2015.
[44] K. Driver, S. Baco, and V. V. Khutoryanskiy, "Hollow capsules formed in a single stage via interfacial hydrogen-bonded complexation of methylcellulose with poly (acrylic acid) and tannic acid," European polymer journal, vol. 49,
no. 12, pp. 4249-4256, 2013.
[45] R. Aveyard, B. P. Binks, and J. H. Clint, "Emulsions stabilised solely by colloidal particles," Advances in Colloid Interface Science, vol. 100, pp. 503-
546, 2003.
[46] B. P. Binks, "Particles as surfactants—similarities and differences," Current
opinion in colloid interface science, vol. 7, no. 1-2, pp. 21-41, 2002.
[47] N. S. El Mogy, "Medical effect of jojoba oil," ed: Google Patents, 2005.
[48] G. Sandha and V. Swami, "Jojoba oil as an organic, shelf stable standard oil-phase base for cosmetic industry," Rasayan Journal of Chemistry, vol. 2, pp.
300-306, 2009.
[49] T. K. Miwa, "Structural determination and uses of jojoba oil," Journal of the
American Oil Chemists' Society, vol. 61, no. 2, pp. 407-410, 1984.
[50] S.-K. Kim and F. Karadeniz, "Biological importance and applications of squalene and squalane," in Advances in food and nutrition research, vol. 65:
Elsevier, 2012, pp. 223-233.
[51] B. Auffray, "Protection against singlet oxygen, the main actor of sebum squalene peroxidation during sun exposure, using Commiphora myrrha essential oil," International journal of cosmetic science, vol. 29, no. 1, pp. 23-
29, 2007.
[52] S. Passi, O. De Pità, P. Puddu, and G. P. Littarru, "Lipophilic antioxidants in human sebum and aging," Free radical research, vol. 36, no. 4, pp. 471-477,
2002.
[53] L. L. Gershbein and E. J. Singh, "Hydrocarbons of dogfish and cod livers and herring oil," Journal of the American Oil Chemists' Society, vol. 46, no. 10, pp.
554-557, 1969.
[54] D. M. Pham, B. Boussouira, D. Moyal, and Q. Nguyen, "Oxidization of squalene, a human skin lipid: a new and reliable marker of environmental pollution studies," International journal of cosmetic science, vol. 37, no. 4, pp.
357-365, 2015.
[55] S. E. Mudiyanselage, P. Elsner, J. J. Thiele, and M. Hamburger, "Ultraviolet A induces generation of squalene monohydroperoxide isomers in human sebum and skin surface lipids in vitro and in vivo," Journal of investigative
dermatology, vol. 120, no. 6, pp. 915-922, 2003.
[56] J.-J. Wang, K. Sung, C.-H. Yeh, and J.-Y. Fang, "The delivery and antinociceptive effects of morphine and its ester prodrugs from lipid emulsions," International journal of pharmaceutics, vol. 353, no. 1-2, pp. 95-
104, 2008.
[57] M. S. Akthar, B. Degaga, and T. Azam, "Antimicrobial activity of essential oils extracted from medicinal plants against the pathogenic microorganisms: a
review," Journal Issues ISSN, vol. 2350, p. 1588, 2014.
[58] K. A. Hammer, C. F. Carson, and T. V. Riley, "Antimicrobial activity of essential oils and other plant extracts," Journal of applied microbiology, vol. 86, no. 6,
pp. 985-990, 1999.
[59] J. Jalas, "Thymus subsect. Pseudomarginati in the Himalayas and adjoining western mountain ranges, and in Caucasia," in Annales Botanici Fennici, 1973,
pp. 104-122
[60] E. Stahl-Biskup and F. Sáez, Thyme: the genus Thymus. CRC Press, 2002.
[61] G. Amin, "Popular medicinal plants of Iran," Ministry of health, pp. 40-47,
1991.
[62] K. Bauer, D. Garbe, and H. Surburg, Common fragrance and flavor materials:
preparation, properties and uses. John Wiley & Sons, 2008.
[63] V. Ryu, D. J. McClements, M. G. Corradini, and L. McLandsborough, "Effect of ripening inhibitor type on formation, stability, and antimicrobial activity of
thyme oil nanoemulsion," Food chemistry, vol. 245, pp. 104-111, 2018.
[64] M. Mastromatteo, G. Barbuzzi, A. Conte, and M. Del Nobile, "Controlled release of thymol from zein based film," Innovative Food Science Emerging
Technologies, vol. 10, no. 2, pp. 222-227, 2009.
[65] E. G. Berg, "A new spin on the old gram stain," ed: American Chemical Society,
2015.
[66] F. Nazzaro, F. Fratianni, L. De Martino, R. Coppola, and V. De Feo, "Effect of essential oils on pathogenic bacteria," Pharmaceuticals, vol. 6, no. 12, pp.
1451-1474, 2013.
[67] S. Burt, "Essential oils: their antibacterial properties and potential applications in foods—a review," International journal of food microbiology, vol. 94, no. 3,
pp. 223-253, 2004.
[68] M. Oussalah, S. Caillet, and M. Lacroix, "Mechanism of action of Spanish oregano, Chinese cinnamon, and savory essential oils against cell membranes and walls of Escherichia coli O157: H7 and Listeria monocytogenes," Journal
of food protection, vol. 69, no. 5, pp. 1046-1055, 2006.
[69] S. Denyer and W. Hugo, "Biocide-induced damage to the bacterial cyctoplasmic membrane," Society for Applied Bacteriology. Technical Series, vol. 27, pp.
171-187, 1991.
[70] J. Gustafson et al., "Effects of tea tree oil on Escherichia coli," Letters in applied
microbiology, vol. 26, no. 3, pp. 194-198, 1998.
[71] S. Cox et al., "Tea tree oil causes K+ leakage and inhibits respiration in Escherichia coli," Letters in applied microbiology, vol. 26, no. 5, pp. 355-358,
1998.
[72] S. K. Ghosh, "Functional coatings and microencapsulation: a general perspective," in Functional coatings WILEY-VCH Verlag GmbH & Co. KGaA,
Weinheim, 2006, pp. 1-28.
[73] E. Onsaard and W. Onsaard, "Microencapsulated Vegetable Oil Powder," in Microencapsulation - Processes, Technologies and Industrial Applications, F.
Salaün, Ed.: IntechOpen, 2019.
[74] Z. Dong, Y. Ma, K. Hayat, C. Jia, S. Xia, and X. Zhang, "Morphology and release profile of microcapsules encapsulating peppermint oil by complex coacervation," Journal of Food Engineering, vol. 104, no. 3, pp. 455-460, 2011.
[75] Q. Shen and S. Y. Quek, "Microencapsulation of astaxanthin with blends of milk protein and fiber by spray drying," Journal of Food Engineering, vol. 123,
pp. 165-171, 2014.
[76] V. Mikulcová, R. Bordes, and V. Kašpárková, "On the preparation and antibacterial activity of emulsions stabilized with nanocellulose particles,"
Food Hydrocolloids, vol. 61, pp. 780-792, 2016.
[77] C. D. Hartono, "Microencapsulation via O/W Pickering Emulsion and W/O
Membrane Emulsification," NTUST, 2018.
[78] M. Mohamed, W. Salleh, J. Jaafar, S. Asri, and A. Ismail, "Physicochemical properties of “green” nanocrystalline cellulose isolated from recycled
newspaper," Rsc Advances, vol. 5, no. 38, pp. 29842-29849, 2015.
[79] H. Celebi and A. Kurt, "Effects of processing on the properties of chitosan/cellulose nanocrystal films," Carbohydrate Polymers, vol. 133, pp.
284-293, 2015.
[80] X. Cao, Y. Habibi, and L. A. Lucia, "One-pot polymerization, surface grafting, and processing of waterborne polyurethane-cellulose nanocrystal nanocomposites," Journal of Materials Chemistry B, vol. 19, no. 38, pp. 7137-
7145, 2009.
[81] L. Chen, J. Zhu, C. Baez, P. Kitin, and T. Elder, "Highly thermal-stable and functional cellulose nanocrystals and nanofibrils produced using fully recyclable organic acids," Green Chemistry, vol. 18, no. 13, pp. 3835-3843,
2016.
[82] Y. W. Chen, T. H. Tan, H. V. Lee, and S. B. Abd Hamid, "Easy fabrication of highly thermal-stable cellulose nanocrystals using Cr (NO3) 3 catalytic hydrolysis system: a feasibility study from macro-to nano-dimensions,"
Materials corrosion, vol. 10, no. 1, p. 42, 2017.
[83] K. Driver, S. Baco, and V. V. Khutoryanskiy, "Hollow capsules formed in a single stage via interfacial hydrogen-bonded complexation of methylcellulose with poly(acrylic acid) and tannic acid," (in English), European Polymer
Journal, vol. 49, no. 12, pp. 4249-4256, 2013.
[84] Z. Xia, A. Singh, W. Kiratitanavit, R. Mosurkal, J. Kumar, and R. Nagarajan, "Unraveling the mechanism of thermal and thermo-oxidative degradation of
tannic acid," Thermochimica Acta, vol. 605, pp. 77-85, 2015.
[85] R. A. Khan et al., "Production and properties of nanocellulose-reinforced methylcellulose-based biodegradable films," J Agric Food Chem, vol. 58, no.
13, pp. 7878-85, 2010.
[86] R. El-Adly, H. Ahmed, F. Modather, A. Enas, and M. Mahmmoud, "Jojoba and castor oils as fluids for the preparation of bio greases: a comparative study," International Journal of Scientific & Engineering Research, vol. 5, pp. 755-
762, 2014.
[87] M. Quilaqueo and J. M. Aguilera, "Crystallization of nacl by fast evaporation of water in droplets of nacl solutions," Food Research International, vol. 84,
pp. 143-149, 2016.