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分别采用静态光散射法(SLS)和凝胶渗透色谱法(GPC)测定了木质素基高效减水剂GCL1-JB的分子量(Mw).由于GCL1-JB直接溶于水中存在聚电解质效应和聚集现象,SLS法测得的分子量(Mw,SLS)远大于GPC测得的分子量(Mw,GPC).为了通过SLS测得GCL1-JB的真实Mw,在GCL1-JB溶液中加入NaCl来屏蔽GCL1-JB的聚电解质效应,并采用0.45μm的微孔滤膜滤除GCL1-JB聚集体.GCL1-JB的动态光散射测试中存在2个扩散峰:快模式峰和慢模式峰.快模式峰对应GCL1-JB的单分子行为,而慢模式峰对应GCL1-JB的聚电解质效应和GCL1-JB聚集体.GCL1-JB动态光散射的慢模式峰随着NaCl的不断加入和进一步的过滤处理而逐渐减弱.当NaCl在溶液中的浓度达到0.1 mol/L,动态光散射的慢模式峰完全消失.在没有慢模式峰存在的条件下利用SLS测得GCL1-JB的绝对分子量为121300,这个分子量被认为是GCL1-JB单分子的真实分子量.然而该条件下SLS法测得的Mw,SLS仍然比GPC法测得的Mw,GPC大,这是由于GCL1-JB与GPC标样NaPSS的构象差异引起的.GCL1-JB的分子构象比NaPSS的更卷曲,所以用NaPSS作为GPC标样得到Mw,GPC比GCL1-JB的真实分子量小.本研究提出了一种利用SLS准确测量GCL1-JB的Mw的方法,对存在聚电解质效应和聚集现象的木质素及其衍生产物的绝对分子量测定具有普遍的借鉴意义.
The molecular weight (Mw) of lignin-based superplasticizer GCL1-JB was measured by static light scattering (SLS) and gel permeation chromatography (GPC), respectively. Because of the polyelectrolyte effect and aggregation of GCL1-JB dissolved directly in water, Phenomenon, the molecular weight (SLS) measured by the SLS method is much larger than the molecular weight (GPC) measured by GPC In order to determine the true Mw of GCL1-JB by SLS, NaCl is added to GCL1-JB solution to shield GCL1- JB polyelectrolyte effect and filtered GCL1-JB aggregates using a 0.45μm microporous membrane.The dynamic light scattering test of GCL1-JB has two diffusion peaks: fast mode and slow mode, GCL1-JB, whereas the slow mode peak corresponds to the polyelectrolyte effect of GCL1-JB and the GCL1-JB aggregates. The slow mode peak of GCL1-JB dynamic light scattering gradually increases with the constant addition of NaCl and further filtration . When the concentration of NaCl in solution reaches 0.1 mol / L, the slow mode of dynamic light scattering completely disappears. The absolute molecular weight of GCL1-JB measured by SLS in the absence of slow mode peak is 121300, Which is considered as the true molecular weight of GCL1-JB single molecule. However, under this condition, the SLS measured Mw , The SLS is still larger than the GPC, GPC and GPC, due to the conformational difference between the GCL1-JB and the GPC standard NaPSS, the molecular conformation of GCL1-JB is more curly than that of NaPSS, NaPSS is used as the GPC standard The molecular weight of GPC was lower than that of GCL1-JB.In this study, a method for accurately measuring the Mw of GCL1-JB by SLS was proposed in this paper to determine the absolute molecular weight of lignin and its derivatives with polyelectrolyte effect and aggregation Has a universal reference.