十六烷基三甲基溴化铵存在下合成锂皂石水分散体的沉降稳定性和老化
Sedimentation stability and aging of aqueous dispersions of Laponite in the presence of cetyltrimethylammonium bromide
摘要：
研究了十六烷基三甲基溴化铵（CTAB）对合成锂皂石水悬浮液沉降稳定性和老化的影响。锂皂石的浓度固定在恒定水平$C_l=2$ %wt，其对应于平衡凝胶IG $_1$和排斥凝胶IG $_2$相之间的阈值。CTAB $C_s$的浓度在0-0.3重量%范围内。在CTAB的存在下，Laponite水性悬浮液对沉降是不稳定的，并且它们分离成上层和底层（分别为U-层和B-层）。动态光散射技术表明，即使在相当小的浓度，$C_s=0.0164$ %wt（$0.03 CEC$）的CTAB的添加，诱导U-层的老化动力学的显着变化，这是由最初不均匀分布在不同Laponite颗粒之间的CTAB分子的平衡来解释。通过转子速度为$ω=500-4000$ rpm的分析离心进行的加速稳定性分析显示了三种沉降状态：连续（I，$C_s<0.14$ %wt）、带状（II，$0.14<C_s<0.2$ %wt）和凝胶状（III，$C_s >0.2$ %wt）。结果表明，B层是“软”的带状制度。$ω$的增加导致其补充压缩和“软”沉积物的崩溃超过一定的临界离心加速度。
英文摘要：
This work discusses the sedimentation stability and aging of aqueous suspension of Laponite in the presence of cetyltrimethylammonium bromide (CTAB). The concentration of Laponite was fixed at the constant level $C_l=2$ %wt, which corresponds to the threshold between equilibrium gel IG$_1$ and repulsive gel IG$_2$ phases. The concentration of CTAB $C_s$ was within 0-0.3 %wt. In the presence of CTAB the Laponite aqueous suspensions were unstable against sedimentation and they separated out into upper and bottom layers (U- and B-layers, respectively). The dynamic light scattering technique revealed that the addition of CTAB even at rather small concentration, $C_s=0.0164$ %wt ($0.03 CEC$), induced noticeable changes in the aging dynamics of U-layer, and it was explained by equilibration of CTAB molecules that were initially non-uniformly distributed between different Laponite particles. Accelerated stability analysis by means of analytical centrifugation with rotor speed $ω=500-4000$ rpm revealed three sedimentation regimes: continuous (I, $C_s<0.14$ %wt), zone-like (II, $0.14<C_s<0.2$ %wt) and gel-like (III, $C_s >0.2$ %wt). It was demonstrated that B-layer was "soft" in the zone-like regime. The increase of $ω$ resulted in its supplementary compressing and the collapse of "soft" sediment above certain critical centrifugal acceleration.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
