二甲基亚砜对间位芳纶结构调控与染色性能的影响研究

Study on the effect of dimethyl sulfoxide on the structural modulation anddyeing properties of PMIA fibers

为了克服间位芳纶染色难以拓展其在服用防护领域的应用,探究不同晶态结构间位芳纶的染色性能差异机理并改善其染色性能具有重要意义。本文选用二甲基亚砜(DMSO)作为PMIA大分子结构调控剂,研究其对PMIA晶态结构和染色性能的影响。采用分子动力学模拟,分别构建了PMIA和DMSO/PMIA不同晶态下的分子模型,并计算DMSO调控前后PMIA的氢键变化、链运动的均方位移及PMIA和染料分子的界面结合能。进一步对PMIA纤维进行扫描电子显微镜(SEM)、傅里叶红外光谱仪(FTIR)、X射线衍射(XRD)表征和表观得色量(K/S值)、上染率的测试,并与分子动力学模拟相互验证,从分子尺度解析了DMSO对PMIA结构调控机制和染色性能的影响。结构模型的计算结果表明:DMSO可以有效地破坏PMIA氢键网络,使得其非结晶区与结晶区氢键数量分别减少了56.5%和25.7%,并显著增加PMIA非结晶区的链运动性能。此外,经调控后的PMIA不同晶态与染料的界面结合能大于调控前,非结晶区与染料的结合能提升程度大于结晶区。实验结果表明:DMSO可有效提高PMIA纤维的表面粗糙度,同时对PMIA的化学结构和结晶度均无明显影响;PMIA的染色性能显著提高,K/S值与上染率分别提升了72.34%和65.6%,耐湿摩擦色牢度提升半级,耐日晒色牢度提升一级。实验结果与分子动力学模拟结论相一致,为提高PMIA的染色性能提供了新途径。

The pdy-m-phenylene isophthalamide(PMIA)fiber is an organic high-performance fiber possessing excellent properties and versatile technical applications.It is widely used in protective clothing fields such as firefighter suits,flame-retardant suits,and racing suits,with great application value.However,due to the presence of abundant hydrogen bonds formed by amide groups along its macromolecular chains,the PMIA fiber has a compact and ordered structure.This compactness and extremely crystalline structure make it challenging for dye molecules to penetrate the PMIA fibers,rendering the dyeing process of PMIA fibers extremely difficult and time-consuming,severely limiting the applications of this kind of high-performance fiber in protective clothing and other fields.Therefore,improving the dyeability of PMIA fibers is crucial to unlock its full application potential and expand its application scope.To address the dyeing difficulties caused by the high hydrogen bonding density in the PMIA molecular structure,extensive research has focused on hydrogen bond regulation of PMIA fibers.Among these,the carrier dyeing method is currently the most commonly used approach for industrial production of dyed PMIA fibers.It utilizes small-molecule organic solvents to penetrate the fibers first,disrupting the hydrogen bond network and increasing the porosity,thereby accelerating dye absorption.However,many carriers used in this method suffer from issues such as irritating odors,high toxicity,and difficult recovery,limiting further applications of the carrier dyeing method.Moreover,research on the microscopic hydrogen bond regulation mechanism of PMIA fibers at the nanoscale is relatively lacking when using carriers,and the effects of carriers on different microscopic crystalline structures of PMIA fibers remain unexplored.Therefore,investigating the mechanism behind the dyeability differences of PMIA fibers with distinct crystalline states and improving their dyeability are of great significance for expanding the applications of PMIA fibers in the textile field.This study employs dimethyl sulfoxide(DMSO),a low-toxicity,low-cost solvent with mature recovery technology,as a hydrogen bond regulator.Molecular dynamics simulations and experiments are combined to study the effects of DMSO on the crystalline structure and dyeability of PMIA.Firstly,molecular models of PMIA and DMSO/PMIA with different crystalline states are constructed based on molecular dynamics simulation theory.The changes in hydrogen bond quantity and length,chain mobility(mean square displacement),and interfacial binding energy between PMIA and dye solution before and after DMSO treatment are calculated.Furthermore,SEM,FTIR,XRD characterisation of the PMIA fabrics are carried out and the apparent colour yield(K/S),dyeing rate and colour fastness are tested to mutually verify the simulation results.The computational results of the structural models demonstrate that DMSO can effectively disrupt the hydrogen bond network of PMIA,reducing the hydrogen bond quantity by 56.5%and 25.7%in the amorphous and crystalline regions,respectively,and significantly enhancing the chain mobility in the amorphous regions.Additionally,the interfacial binding energies between PMIA with different crystalline states and the dye molecules are higher after DMSO treatment,with a more substantial increase observed in the amorphous regions compared to the crystalline regions.Experimental results reveal that DMSO can effectively increase the surface roughness of PMIA fibers without significantly affecting their chemical structure and crystallinity.Meanwhile,the dyeability of PMIA is remarkably improved,with the K/S value and dye exhaustion increasing by 72.34%and 65.6%,respectively,and the wet rubbing fastness and light fastness enhancing by half a grade and one grade,respectively.The experimental results are consistent with the molecular dynamics simulation conclusions.This study provides a mechanistic guideline for selecting hydrogen bond regulators for PMIA fibers and offers new insights into improving the dyeability of PMIA fibers.