Glyn O. Phillips Hydrocolloid Research Centre at HBUT, School of Food and Biological Engineering, Hubei University of Technology, Wuhan, Hubei 430068, China.
Centre for Polymer from Renewable Resource, South China University of Technology, Guangzhou, Guangdong 510640, China; Department of Materials Engineering, Monash University, Melbourne, VIC 3168, Australia.
Int J Biol Macromol. 2019 May 15;129:679-685. doi: 10.1016/j.ijbiomac.2019.02.019. Epub 2019 Feb 7.
This work concerns how crosslinker amount (N, N'-methylene-bisacrylamide) affects the microstructural, absorbent and rheological features of one-step prepared starch-based superabsorbent polymers at a high starch concentration (0.27:1 w/w starch-water). The increased crosslinker amount evidently altered the microstructure and the absorbent and rheological features. Then, the variations in starch-based superabsorbent polymer properties were discussed from a microstructure viewpoint. Particularly, the higher crosslinker quantity rose the crosslinking density and the ratio (GR) of grafted anhydroglucose unit on starch backbone (from 27% to 52%), but short the average polyacrylamide (PAM) chain length (L). These structural features suppressed the chain stretch within starch-based superabsorbent polymer fractal gels (confirmed by smaller R value) and promoted the formation of smaller chain networks, thus weakening the water absorption to the starch-based superabsorbent polymer chain networks. Also, the increased GR and reduced L, with lowered chain extension and elevated crosslinking density, probably decreased the flexibility and mobility of chain segments in starch-based superabsorbent polymer gel matrixes. This caused the enhanced robustness and storage modulus of the gels with reduced chain energy dissipation ability.
这项工作研究了在高淀粉浓度（0.27:1 w/w 淀粉-水）下，交联剂用量（N，N'-亚甲基双丙烯酰胺）如何影响一步法制备的淀粉基高吸水性聚合物的微观结构、吸水性和流变性能。增加交联剂用量明显改变了微观结构以及吸水性和流变性能。然后，从微观结构的角度讨论了淀粉基高吸水性聚合物性能的变化。特别是，较高的交联剂用量会增加交联密度和淀粉主链上接枝的无水葡萄糖单元的比例（从 27%增加到 52%），但会缩短聚丙烯酰胺（PAM）链的平均长度（L）。这些结构特征抑制了淀粉基高吸水性聚合物分形凝胶内的链拉伸（通过较小的 R 值证实），并促进了较小链网络的形成，从而削弱了水对淀粉基高吸水性聚合物链网络的吸收。此外，GR 的增加和 L 的降低，伴随着链延伸的降低和交联密度的升高，可能降低了淀粉基高吸水性聚合物凝胶基质中链段的柔韧性和迁移性。这导致了凝胶的增强鲁棒性和储能模量，同时降低了链的能量耗散能力。
