Surface-initiated ring-opening polymerization from cellulose model surfaces monitored by a Quartz Crystal Microbalance
Surface-initiated ring-opening polymerization from cellulose model surfaces monitored by a Quartz Crystal Microbalance
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DOI：
10.1039/c1sm06121f
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发表时间：
2012-01-01
期刊：
影响因子：
3.4
通讯作者：
Carlmark, Anna
中科院分区：
文献类型：
--
作者：
Carlsson, Linn;Utsel, Simon;Carlmark, Anna
聚合物表面接枝是一种很好的表面改性方法。然而，由于缺乏合适的表征方法和工具来监测聚合反应，表面引发聚合仍然相对较少被理解。本文报道了用石英晶体微天平(QCM)技术实时研究原位表面引发开环聚合(SI-ROP)。聚合是从纤维素模型表面进行的，聚合是直接从纤维素上的可用羟基引发的。使用环状单体3-己内酯和有机催化剂1，5，7-三氮杂双环[4.4.0]十二碳-5-烯(TBD)，在室温下进行本体反应。由于在从表面接枝的同时形成了大量的自由聚合物，因此反应分三个循环进行，其间有漂洗步骤，以仅测量表面接枝的效果。频率的变化表明，在每个循环后，聚合物的接枝量增加，表明大部分链端保持活性。聚合物接枝后，纤维素模型表面表现出更强的疏水性，表面粗糙度降低。这项研究清楚地表明，QCM是一种从纤维素表面原位监测SI-ROP的可行方法。我们相信，这是朝着更深入地理解如何在生物复合材料中定制聚合物改性纤维素和聚合物基质之间的界面迈出的重要一步。
Polymer surface-grafting is an excellent method to modify the properties of a surface. However, surface-initiated polymerization is still relatively poorly understood due to the lack of appropriate characterization methods and tools to monitor the polymerizations. Herein, we report the in situ, surface-initiated ring-opening polymerization (SI-ROP) investigated in real time by the Quartz Crystal Microbalance (QCM) technique. The polymerization was performed from a cellulose model surface and the polymerization was initiated directly from the available hydroxyl groups on the cellulose. The cyclic monomer 3-caprolactone and an organic catalyst, 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), were used, and the reaction was performed in bulk at room temperature. Since a free polymer was formed in bulk in parallel to the grafting from the surface, the reaction was performed in three cycles with rinsing steps in between to measure only the effect of the surface grafting. The change in frequency showed that the grafted amount of polymer increased after each cycle indicating that most of the chain ends remained active. After polymer grafting, the cellulose model surface showed a more hydrophobic character, and the surface roughness of the cellulose model surface was reduced. This study clearly shows that QCM is a viable method to monitor SI-ROP in situ from cellulose surfaces. We believe this is an important step towards a deeper understanding of how to tailor the interface between polymer-modified cellulose and a polymer matrix in biocomposites.