Pipertzis Achilleas, Chroni Angeliki, Pispas Stergios, Swenson Jan
Department of Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden.
Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vassileos Constantinou Ave., 11635 Athens, Greece.
Polymers (Basel). 2025 Jul 2;17(13):1857. doi: 10.3390/polym17131857.
This study investigates the mechanical properties of double hydrophilic block copolymers (DHBCs) based on poly[oligo(ethylene glycol) methacrylate] (POEGMA) and poly(vinyl benzyl trimethylammonium chloride) (PVBTMAC) blocks by employing small amplitude oscillatory shear (SAOS) rheological measurements. We report that the mechanical properties of DHBCs are governed by the interfacial glass transition temperature (), verifying the disordered state of these copolymers. An increase in zero shear viscosity can be observed by increasing the VBTMAC content, yielding a transition from liquid-like to gel-like and finally to an elastic-like response for the PVBTMAC homopolymer. By changing the block arrangement along the backbone from statistical to sequential, a distinct change in the viscoelastic response is obvious, indicating the presence/absence of bulk-like regions. The tunable viscosity values and shear-thinning behavior achieved through alteration of the copolymer composition and block arrangement along the backbone render the studied DHBCs promising candidates for drug delivery applications. In the second part, the rheological data are analyzed within the framework of the classical free volume theories of glass formation. Specifically, the copolymers exhibit reduced fractional free volume and similar fragility values compared to the PVBTMAC homopolymer. On the contrary, the activation energy increases by increasing the VBTMAC content, reflecting the required higher energy for the relaxation of the glassy VBTMAC segments. Overall, this study provides information about the viscoelastic properties of DHBCs with densely grafted macromolecular architecture and shows how the mechanical and dynamical properties can be tailored for different drug delivery applications by simply altering the ratio between the two homopolymers.
本研究通过小振幅振荡剪切（SAOS）流变测量，研究了基于聚[甲基丙烯酸寡聚（乙二醇）酯]（POEGMA）和聚（乙烯基苄基三甲基氯化铵）（PVBTMAC）嵌段的双亲水嵌段共聚物（DHBCs）的力学性能。我们报告称，DHBCs的力学性能受界面玻璃化转变温度（）控制，证实了这些共聚物的无序状态。通过增加VBTMAC含量，可以观察到零剪切粘度增加，PVBTMAC均聚物从类液体响应转变为类凝胶响应，最终转变为类弹性响应。通过将主链上的嵌段排列从无规变为有序，粘弹性响应有明显变化，表明存在/不存在块状区域。通过改变共聚物组成和主链上的嵌段排列实现的可调粘度值和剪切变稀行为，使所研究的DHBCs成为药物递送应用的有前途的候选材料。在第二部分中，在玻璃形成的经典自由体积理论框架内分析流变数据。具体而言，与PVBTMAC均聚物相比，共聚物表现出降低的分数自由体积和相似的脆性值。相反，活化能随着VBTMAC含量的增加而增加，反映了玻璃态VBTMAC链段松弛所需的更高能量。总体而言，本研究提供了关于具有密集接枝大分子结构的DHBCs粘弹性性质的信息，并展示了如何通过简单改变两种均聚物之间的比例，为不同的药物递送应用定制力学和动力学性质。
