For the application of superabsorbent polymer (SAP) particles in personal hygiene products such as disposable diapers, the SAP surface is additionally crosslinked to minimize gel blocking and enhance absorbency under external pressure. Physically surface-crosslinked poly(acrylic acid)(PAA)-based SAP microspheres were prepared using polycations (branched polyethylene imine (bPEI) and polyamidoamine (PAMAM)). Compared with chemical crosslinking, which requires high temperature and prolonged reaction, physical crosslinking via electrostatic interaction between the polycations and negatively charged PAA chains was achieved within 20 min at room temperature. The polycation-crosslinked SAP particles had a rougher surface and lower water absorption capacity. The thickness of the physically crosslinked surface, visualized using fluorescence labeled polycations, increased with increasing polycation concentration and reaction time, eventually reaching saturation. PAMAM produced mechanically stronger and thicker surface-crosslinking than bPEI, owing to its lower molecular weight. Micro-CT analysis of the collective swelling behavior of a gel bed packed with the SAP particles confirmed that the shapes of the SAP particles crosslinked with polycations were better maintained during swelling and there was a greater void fraction in the packed gel bed than with the use of bare SAP particles, which might minimize gel blocking and improve the permeability of fluid through gel bed.

为了将超吸收性聚合物（SAP）颗粒应用于个人卫生产品（如一次性尿布）中，SAP表面需要进行额外的交联以最大程度地减少凝胶阻塞并在外部压力下增强吸收能力。使用聚阳离子（支化聚乙烯亚胺（bPEI）和聚酰胺基胺（PAMAM））制备基于物理表面交联的聚丙烯酸（PAA）的SAP微球。与需要高温和延长反应时间的化学交联相比，在室温下20分钟内，通过聚阳离子和带负电荷的PAA链之间的静电相互作用实现了物理交联。聚阳离子交联的SAP颗粒具有较粗糙的表面和较低的吸水能力。物理交联表面的厚度，使用荧光标记的聚阳离子可视化，随聚阳离子浓度和反应时间的增加而增加，最终达到饱和。由于其分子量较低，与BPEI相比，PAMAM在机械上产生了更牢固，更厚的表面交联。对填充有SAP颗粒的凝胶床的集体膨胀行为的Micro-CT分析证实，与聚阳离子交联的SAP颗粒的形状在膨胀过程中得到了更好的保持，并且填充凝胶床中的空隙率比使用时更大裸露的SAP颗粒，可以最大程度地减少凝胶阻塞，并提高流体通过凝胶床的渗透性。由于其分子量较低，与BPEI相比，PAMAM在机械上产生了更牢固，更厚的表面交联。对填充有SAP颗粒的凝胶床的集体膨胀行为的Micro-CT分析证实，与聚阳离子交联的SAP颗粒的形状在膨胀过程中得到了更好的保持，并且填充凝胶床中的空隙率比使用时更大裸露的SAP颗粒，可以最大程度地减少凝胶阻塞，并提高流体通过凝胶床的渗透性。由于其分子量较低，与BPEI相比，PAMAM在机械上产生了更牢固，更厚的表面交联。对填充有SAP颗粒的凝胶床的集体膨胀行为的Micro-CT分析证实，与聚阳离子交联的SAP颗粒的形状在膨胀过程中得到了更好的保持，并且填充凝胶床中的空隙率比使用时更大裸露的SAP颗粒，可以最大程度地减少凝胶阻塞，并提高流体通过凝胶床的渗透性。