本文以CBMA水凝胶为研究对象,进而讨论不同含水量下的水凝胶的指标变化情况。首先,我们给出水凝胶的分子动力学模型,并且模拟随着时间的增加,侧链的寿命自相关函数表现出不同的变化趋势。其次,在含水量为62%至71%之间,侧链对的特征寿命表现出大幅下降的趋势。最后,研究发现CBMA水凝胶中侧链对的数目在含水量大于62%时数目逐渐减少。模拟结果与已有的实验结果保持一致。
In this paper, CBMA hydrogel is used as the research object and then the change of hydrogel index under different water contents is mainly discussed. First of all, molecular dynamics model of hy-drogel is provided. It is simulated that lifetime autocorrelation functions are expressed with vari-ation trends as the time scale increases. Furthermore, it is shown that a large decrease in charac-teristic lifetime of side-chain pairs occurs between 62% water content and 71% water content. Finally, the number of side-chain pairs in hydrogels decreases quickly over 62% water content according to the simulation results. This point is the same as the results of the available experi-mental results.
水凝胶,含水量,寿命, Hydrogel Water Content Lifetime不同含水量下水凝胶的性能研究
C p a i r ( t ) = 1 N p ∑ i = 1 N p 〈 P ( 0 ) P ( t ) 〉 〈 P ( 0 ) 〉 2
其中如果左旋侧链对在时间 t 存在时, P ( t ) 是一个等于1的二元函数,否则, P ( t ) 等于0;当时间等于0时, N p 是水凝胶中左旋侧链对的个数;断括号 ( 〈 〉 ) 表示总体平均值。寿命相关函数的慢衰变表示左旋侧链对之间的关系更稳定。为了更清晰的了解自相关函数的变化规律,我们画出相应的图形。羧甜莱碱甲基丙烯酸甲酯(CBMA)水凝胶作为含水量的函数,如图1绘制出CBMA水凝胶中侧链的寿命自相关函数。
图1. CBMA水凝胶中侧链对的寿命自相关函数
从图1中把时间 t 作为横坐标,作为水含量函数的荷电对寿命 C 1 ( t ) 作为纵坐标,我们观察到随着时间的逐渐增加,结果表明,当含水量超过62%时,两性离子对的寿命迅速下降。另一方面,当水含量低于62%时,两性离子对的寿命曲线基本相同,衰减较慢,表明存在稳定的缔合关系,即物理交联。
为了定量地测量这一差异,通过将指数衰减函数拟合到 C p a i r ( t ) 曲线上,得到了平均寿命如下:
C p a i r ( t ) = A p exp ( − t τ p )
其中 A p 是振幅, τ p 是平均寿命。以含水量为横坐标,侧链对的特征寿命作为纵坐标,画出特征寿命的变化趋势,如下图2。
魏 林,武 婕,于蓉蓉,惠小健. 不同含水量下水凝胶的性能研究Research of the Properties of Hydrogels with Various Water Contents[J]. 自然科学, 2018, 06(06): 432-436. https://doi.org/10.12677/OJNS.2018.66056
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