College of Light Industry and Chemical Engineering, Dalian Polytechnic University, Dalian, Liaoning, 116034, China.
Sci Rep. 2018 Sep 27;8(1):14450. doi: 10.1038/s41598-018-32672-z.
Thermo-sensitive gel exhibits great potential industrial application. It has been widely used in tissue repair, drug release and water purification for its property of phase transition in response to external stimuli, reusability and biocompatibility. In this study, a novel lignin-based thermo-sensitive gel was synthesized with alkali lignin by two steps. Firstly, phenolated lignin (PPAL) was synthesized with purified alkali lignin (PAL) catalyzed by sulfuric acid. Subsequently, thermo-sensitive gel was achieved by thermal polymerization of phenolated alkali lignin and N-isopropylacrylamide (NIPAAm). Furthermore, the prepared hydrogels were characterized in terms of thermal behavior, interior morphology and their swelling behavior. Compared with PAL-based gel, the obtained PPAL-based gel exhibits a higher crosslinking density and lower critical solution temperature (LCST) due to the increase of reaction site and smaller space volume of the hydrophobic side groups grafted on NIPAAm. TGA data revealed that thermal stability of gel was enhanced (50% weight loss at ~380 °C) by using lignin as precursor. SEM images showed that a more regular interior morphology, better compressive strength was also found (PPAL0.05, 11.15 KPa). Furthermore, the swelling ratio of PPAL-based gel was lower than that of PAL-based gel due to its more complex structure.
温敏凝胶因其对外界刺激的相转变、可重复使用性和生物相容性而具有巨大的潜在工业应用价值。它已广泛应用于组织修复、药物释放和水净化等领域。在本研究中，通过两步法用碱木质素合成了一种新型木质素基温敏凝胶。首先，用硫酸催化纯化的碱木质素（PAL）合成了酚化木质素（PPAL）。随后，通过热聚合酚化碱木质素和 N-异丙基丙烯酰胺（NIPAAm）制备了温敏凝胶。此外，还对所制备的水凝胶进行了热行为、内部形貌和溶胀行为的表征。与基于 PAL 的凝胶相比，由于接枝在 NIPAAm 上的疏水性侧基的反应位点增加和空间体积减小，所得的 PPAL 基凝胶具有更高的交联密度和更低的临界溶液温度（LCST）。TGA 数据表明，使用木质素作为前体可以提高凝胶的热稳定性（在约 380°C 时 50%的重量损失）。SEM 图像表明，由于其更复杂的结构，PPAL 基凝胶具有更规则的内部形态和更好的压缩强度（PPAL0.05，11.15kPa）。此外，由于其更复杂的结构，PPAL 基凝胶的溶胀率低于 PAL 基凝胶。
