聚氨酯脲/纖維素混摻高分子靜電紡絲纖維的分子排列與物理性質探討

Molecular Arrangement and Physical Properties of Polyurethane-urea/Cellulose Blend Electrospun Fibers

曾榆凱(Yu-Kai Tseng)

指導教授 ： 林唯芳

國立臺灣大學/工學院/材料科學與工程學研究所/碩士(2018年)

https://doi.org/10.6342/NTU201804329

摘要

高分子混摻又稱為高分子合金，指在沒有化學鍵結的產生下，將兩種或兩種以上的高分子以物理方式進行混合。理想的高分子混摻會同時具備原材料的優點與特性，但並不會過度受其缺點所影響，是能獲得材料特性最佳化可能性的一種方式。而在高分子混摻上，選取正確的原材料將會是相當重要的一環，如果兩高分子間能夠產生額外的交互作用力，就能夠形成理想的高分子混摻；然而，目前絕大多數的研究，都是以合成高分子進行混摻，雖具有不錯的物理性質，但較低的生物相容性限制了材料在其他領域的發展，同時也較少研究團隊針對具方向性排列纖維進行分子排列與物理性質的探討。因此我們期望利用物理混摻，將合成高分子與天然高分子進行混合後，製備出三種不同形貌結構，同時又具有良好生物相容性的高分子混摻樣品：具方向性排列纖維、不具方向性排列纖維與滴鑄薄膜。
在本研究中，我們合成出低毒性生物可降解聚氨酯脲，並分別與不同濃度的乙基纖維素及纖維素奈米纖維進行混摻，期許藉由材料間的交互作用力，製備出具有良好生物相容性的理想高分子混摻。纖維素奈米纖維的直徑約20奈米，長度則約數百奈米到數微米。接著我們以靜電紡絲技術與滴鑄薄膜法製備出三種不同形貌結構的高分子混摻樣品：具方向性排列纖維、不具方向性排列纖維與滴鑄薄膜，藉由精準調控參數，紡絲纖維的線寬都可控制在一微米左右。本研究從摻雜濃度與形貌結構兩個面向，探討其分子排列與機械性質、熱性質之間的相互關係。
從化學結構環境、結晶度與奈米結構變化的趨勢顯示出，乙基纖維素可以與聚氨酯脲混合的均勻，對分子間作用力具有相當程度的影響，其中，當乙基纖維素含量為50%時，樣品呈現最佳的熱穩定性質與機械強度，表示此時兩高分子混摻的最好；纖維素奈米纖維則對於結晶度與分子排列規整度具有非常卓越的幫助，這可能來自於奈米纖維輔助的結晶行為，對於機械強度的提升效果不容忽視；同時，熱穩定性質也隨著含量增加而些許提升。三種不同形貌結構的樣品中，具方向性排列纖維具有最佳的結晶度、分子排列規整度與機械強度，其次為不具方向性排列纖維。此外，具有較佳分子排列規整度的樣品，都呈現出更好的機械強度表現，顯示出分子排列規整度確實與機械強度具有高度關係。

關鍵字

聚氨酯脲 ； 纖維素 ； 奈米纖維 ； 混摻 ； 靜電紡絲 ； 機械性質 ； 熱性質 ； 結晶

並列摘要

Polymer blend is also known as polymer alloy. Refer to the physical mixing of two or more polymers without the formation of chemical bonds. If two polymers can generate extra interaction, the ideal polymer blend can be formed. Ideal polymer blend will have advantages and characteristics of raw materials at the same time, but it will not be affected by their shortcomings seriously. However, most of the current researches are using synthetic polymers to manufacture polymer blend. Although these materials have good physical properties, the low biocompatibility limits the possibility in other fields. Furthermore, there are few research teams study the relationship between molecular arrangement and physical properties of aligned fibers. So we blend synthetic polymer with natural polymer, and manufacture three different morphology samples. They are aligned fibers, isotropic fibers and drop films. We hope that these samples will not only have good biocompatibility but also nice physical properties.
In this study, we have synthesized a low-toxicity biodegradable polyurethane-urea. Then we blend polyurethane-urea with ethyl cellulose and cellulose nanofiber, respectively. We expect that these polymers can mix uniformly by the interaction between raw materials. The diameter of cellulose nanofiber is about 20 nanometer, and the length of it is from hundreds of nanometers to several micrometers. The two series of polymer blend are then processed by electrospinning and drop-casting to manufacture three different types of samples. They are aligned fibers, isotropic fibers and drop films. By the precise control of electrospinning parameters, the fiber width are all about one micron. We will discuss the relationship among molecular arrangement, mechanical properties and thermal properties from the aspects of doping concentration and morphology.
By the changing tendency of chemical environment, crystallinity, and nanostructure, it is shown that ethyl cellulose blends well with polyurethane-urea. And it has a significant influence on the intermolecular force. When the content of ethyl cellulose is fifty percent, this sample exhibits best thermal stability, indicating that it has the strongest interaction among these samples. On the other hand, cellulose nanofiber is very helpful for crystallinity and molecular arrangement. It may come from the nanofiber-assisted crystallization. This effect upon the enhancement of mechanical properties should not be ignored. Besides, The thermal stability is also improved with the increase of the content. Among these samples, aligned fibers have the best crystallinity, molecular arrangement and mechanical strength, the second place is isotropic fibers. Moreover, the samples with better molecular arrangement exhibit better mechanical strength, indicating that these two properties are highly correlated.

並列關鍵字

Polyurethane-urea ； Cellulose ； nanofiber ； blend ； electrospin ； mechanical properties ； thermal properties ； crystallization

參考文獻

1. Wei-Fang Su, Principles of Polymer Design and Synthesis. Springer, 2013. 44.

2. Daoyong Mao, Qing Li, Ningning Bai, Hongzhou Dong, Daikun Li, Porous stable poly(lactic acid)/ethyl cellulose /hydroxyapatite composite scaffolds prepared by a combined method for bone regeneration. Carbohydrate Polymers, 2018. 180, 104-111.

3. Keita Sakakibara, Hiroyuki Yano, Yoshinobu Tsujii, Surface Engineering of Cellulose Nanofiber by Adsorption of Diblock Copolymer Dispersant for Green Nanocomposite Materials. ACS Applied Materials and Interfaces, 2016. 8(37), 24893-24900.

4. Robert L. Scott, The Thermodynamics of High Polymer Solutions. IV. Phase Equilibria in the Ternary System: Polymer—Liquid 1—Liquid 2. The Journal of Chemical Physics, 1949. 17(3), 268-279.

5. H. Tompa, Phase relationships in polymer solutions. Transactions of the Faraday Society, 1949. 45, 1142-1152.