3D printable colloidal dispersions demonstrating sol-to-gel transition at low silica concentrations mediated by molecular weight distribution of polypropylene glycol oligomer

IF 5.4 1区化学 Q2 CHEMISTRY, MULTIDISCIPLINARY

GIANT Pub Date : 2025-02-20 DOI:10.1016/j.giant.2025.100353

Sai Wu , Qingxu Zhang , Shihao Xiao , Li'an Zhang , Chaoyi Fan , Jinpeng Wang , Jian Wang , Yijun Shen , Yihu Song , Qiang Zheng

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Abstract

Thixotropic colloidal gels composed by hydrophilic silica and polypropylene glycol (PPG) oligomer fluidize upon shear and solidify upon cease of flow, facilitating their use in 3D printing. In this study, we present a novel approach to high-fidelity 3D printing that leverages a dual-stream mixing technique within the printer nozzle for the first time. This innovative method enables the precise fabrication of colloidal objects even at low volume fractions (φ) of filler. The printed gels, containing a pre-stored crosslinker, can be further processed into polyurethane nanocomposites, broadening their potential applications. Rheological studies demonstrate that the sol-gel transition in these systems can be effectively controlled by adjusting the molecular weight distribution of the polydisperse PPG oligomers. This investigation has led to the creation of a comprehensive polydispersity-molecular weight-φ phase diagram that characterizes the behavior of the gels under different conditions. Moreover, the mechanistic studies reveal that gelation of polydisperse oligomers occurs at significantly lower φ compared to monodisperse systems, which is attributed to the formation of thicker glassy layers surrounding the silica nanoparticles. Our findings provide valuable insights into the design and optimization of thixotropic gels, making them promising candidates for various applications requiring precise rheological control in materials science.

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在聚丙烯乙二醇低聚物分子量分布介导的低二氧化硅浓度下，3D打印胶体分散体显示溶胶到凝胶的转变

由亲水性二氧化硅和聚丙烯乙二醇（PPG）低聚物组成的触变胶体，剪切后流化，停止流动后固化，便于在3D打印中使用。在这项研究中，我们首次提出了一种高保真3D打印的新方法，该方法利用了打印机喷嘴内的双流混合技术。这种创新的方法使得即使在填料的低体积分数（φ）下也能精确制造胶体物体。打印的凝胶含有预先储存的交联剂，可以进一步加工成聚氨酯纳米复合材料，扩大了它们的潜在应用。流变学研究表明，通过调节多分散PPG低聚物的分子量分布，可以有效地控制这些体系中的溶胶-凝胶转变。这项研究导致了一个综合的多分散性-分子量-φ相图的创建，表征了凝胶在不同条件下的行为。此外，机理研究表明，与单分散体系相比，多分散低聚物的凝胶化发生在明显较低的φ下，这是由于二氧化硅纳米颗粒周围形成了更厚的玻璃层。我们的研究结果为触变凝胶的设计和优化提供了有价值的见解，使它们成为材料科学中需要精确流变控制的各种应用的有希望的候选者。

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来源期刊

GIANT Multiple-

CiteScore

8.50

自引率

8.60%

发文量

审稿时长

42 days

期刊介绍： Giant is an interdisciplinary title focusing on fundamental and applied macromolecular science spanning all chemistry, physics, biology, and materials aspects of the field in the broadest sense. Key areas covered include macromolecular chemistry, supramolecular assembly, multiscale and multifunctional materials, organic-inorganic hybrid materials, biophysics, biomimetics and surface science. Core topics range from developments in synthesis, characterisation and assembly towards creating uniformly sized precision macromolecules with tailored properties, to the design and assembly of nanostructured materials in multiple dimensions, and further to the study of smart or living designer materials with tuneable multiscale properties.