摘要
在机械化学条件下理解固-固相转化的作用机制对于实现多晶型的精确控制至关重要。在本研究中,对一系列奇数直链饱和二元酸(DAn,其中DA表示二元酸,n表示碳原子数)在球磨条件下的固-固相转化进行了研究。结果表明,相变不仅受二元酸自身链长的影响,还受辅助研磨溶剂的脂肪酸链长的影响。在无溶剂的球磨条件下,约58.4%的DA7的晶型Ⅰ转变为晶型Ⅱ,而DA9和DA11晶型Ⅰ的转变量分别降至约12.0%和11.0%,DA5的晶型Ⅰ则没有发生任何相转化。在长链脂肪酸溶剂辅助研磨的情况下,随着溶剂链长的增加,DA7的相转化率先增加后减少。相反,短链脂肪酸能显著抑制从晶型Ⅰ到晶型Ⅱ的相变,用甲酸、乙酸和丙酸辅助研磨时均未制备出晶型Ⅱ。基于密度泛函理论的计算表明,不同链长的奇数直链饱和二元酸的固-固相变与其构象转换能垒有关,随着链长的增加,构象的转化能垒逐渐提高。DA5晶型Ⅱ的相邻分子间的位错是不发生相转化的关键原因。在溶剂辅助研磨的条件下,由疏水作用和氢键相互作用所主导的表面溶剂化是促进相转化的主要原因。本研究为深入理解直链饱和二元酸的固-固相变机制,以及为通过机械化学条件实现多晶型的可控制备提供了理论基础和实验依据。
Understanding the mechanism of the solid-solid phase transition under mechanochemical conditions is crucial for the precise control of polymorph.In this study,the solid-solid phase transition of a series of α,ω-alkanedicarboxylic acids(DAn,where DA represents dicarboxylic acid and n represents the number of carbon atoms in the molecule,n=5,7,9,11)under ball-mill grinding are studied.The phase transition is not only influenced by the chain length of the α,ω-alkanedicarboxylic acids but also by the chain length of the fatty acids used as auxiliary grinding agents.Under ball-mill grinding without liquid,approximately 58.4%form Ⅰ of DA7 transform to form Ⅱ,while the amount decreases to about 10% for DA9 and DA11 and 0 for DA5.Under long chain fatty acid assisted grinding,along with the increase of chain,the phase transition amount of DA7 first increases and then decreases.However,the short chain fatty acid can significantly inhibit the phase transition from form Ⅰ to form Ⅱ and no form Ⅱ was prepared with formic acid,acetic acid and propionic acid.The density functional theory(DFT)calculations revealed that the solid-solid phase transition of α,ω-alkanedicarboxylic acids with different chains is related to their conformation conversion energy barrier.As the chain length increases,the energy barrier for conformational conversion also rises,thereby hindering the phase transition process.Notably,for DA5,the absence of the phase transition can be attributed to the dislocation of the adjacent molecules.Under solventassisted milling conditions,surface solvation,dominated by hydrophobic interactions and hydrogen bonding,is the main reason for promoting phase transformation.This study provides a theoretical basis and experimental evidence for a deeper understanding of the solid-solid phase transformation mechanism ofα,ω-alkanedicarboxylic acids and for the controllable preparation of polymorphs under mechanochemical conditions.
作者
林家伟
卓之奥
杨在卿
吴送姑
龚俊波
LIN Jiawei;ZHUO Zhi’ao;YANG Zaiqing;WU Songgu;GONG Junbo(School of Chemical Engineering and Technology,State Key Laboratory of Chemical Engineering and Low-carbon Technology,Tianjin University,Tianjin 300072,China)
出处
《化工学报》
北大核心
2026年第1期265-274,共10页
CIESC Journal
基金
国家自然科学基金项目(22178254)
天津市青年科技人才项目(QN20230220)。
关键词
结晶
多晶型
直链饱和二元酸
相转化
机械化学
crystallization
polymorph
α,ω-alkanedicarboxylic acids
phase transition
mechanochemistry
