Ruffini Eleonora, Bellinetto Emanuela, Turri Stefano, Griffini Gianmarco
Department of Chemistry, Materials and Chemical Engineering "Giulio Natta", Politecnico di Milano, Piazza Leonardo da Vinci 32, Milano 20133, Italy.
ACS Omega. 2025 Jun 21;10(25):27585-27597. doi: 10.1021/acsomega.5c03665. eCollection 2025 Jul 1.
In this work, a Design-of-Experiments (DoE) methodology was adopted to study and optimize the ultrasonication process of lignin in water to obtain lignin nanoparticles (LNPs) so as to establish qualitative and quantitative cause-effect relationships between the operating variables (i.e., lignin concentration, processing time, and sonication amplitude) and the distinctive features of the so-obtained nanostructured materials. Monitoring the evolution of the chemical, physical, morphological, and thermal characteristics of lignin upon ultrasonic irradiation enabled the identification of the most relevant process parameters (viz., factors) affecting the average particle size and shape, concentration of hydroxyl/carboxyl groups, and suspended fraction of particles, which were taken as the target materials characteristics (viz., systems responses). Interestingly, the selection of suitable process conditions allowed to obtain exclusively spherical LNPs with perfectly circular shape profile, thus providing the first demonstration of the formation of lignin nanospheres through a size-reduction method not relying on the use of solvents or other chemicals. Furthermore, highly predictive fitting models were generated and validated to accurately and reliably estimate the system responses at any experimental point within the investigation range. As a validation of such process optimization, poly-(vinyl alcohol) (PVA) films incorporating up to 20% (w/w) of either pristine or ultrasound-treated lignin were prepared so as to evaluate the effect of tailored lignin (nano)-particle characteristics on the chemical, morphological, thermal, and mechanical properties of the resulting (nano)-composite systems. The nanometric size of LNPs, together with their spherical morphology and lower molecular weight vs pristine systems was found to foster stronger matrix-filler interactions and improved distributive mixing within the PVA matrix, ultimately leading to higher-performance nanocomposite materials. This work provides new insights into the production of LNPs via ultrasonication, demonstrating that precise control over their size, morphology, and chemical functionalities can be predictively attained by the optimal tuning of relevant process parameters.
在本研究中，采用实验设计（DoE）方法来研究和优化木质素在水中的超声处理过程，以制备木质素纳米颗粒（LNP），从而建立操作变量（即木质素浓度、处理时间和超声振幅）与所得纳米结构材料独特特性之间的定性和定量因果关系。监测超声辐照下木质素的化学、物理、形态和热特性的演变，有助于确定影响平均粒径和形状、羟基/羧基浓度以及颗粒悬浮分数的最相关工艺参数（即因素），这些参数被视为目标材料特性（即系统响应）。有趣的是，选择合适的工艺条件能够仅获得具有完美圆形轮廓的球形LNP，从而首次证明了通过不依赖于使用溶剂或其他化学物质的尺寸减小方法形成木质素纳米球。此外，生成并验证了高度预测性的拟合模型，以准确可靠地估计研究范围内任何实验点的系统响应。作为这种工艺优化的验证，制备了含有高达20%（w/w）原始或超声处理木质素的聚（乙烯醇）（PVA）薄膜，以评估定制的木质素（纳米）颗粒特性对所得（纳米）复合体系的化学、形态、热和机械性能的影响。发现LNP的纳米尺寸及其球形形态以及相对于原始体系较低的分子量有助于在PVA基体中形成更强的基体-填料相互作用并改善分布混合，最终得到高性能的纳米复合材料。这项工作为通过超声处理生产LNP提供了新的见解，表明通过对相关工艺参数的优化调整，可以预测性地精确控制其尺寸、形态和化学功能。
