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《合成橡胶工业》[ISSN:1000-1255/CN:62-1036/TQ]

期数:

2024年6期

页码:

507

栏目:

出版日期:

1900-01-01

文章信息/Info

Title:

Synthesis of polyfarnesene based on aqueous free-radical polymerization and molecular dynamics simulation of its properties

文章编号:

1000-1255（2024）06-0503-04

作者:

吴明丽; 蒋 晶; 王小雨; 王灿才; 王庆富; 曹 兰

青岛科技大学 高分子科学与工程学院，山东 青岛266042

Author(s):

WU Ming-li;  JIANG Jing;  WANG Xiao-yu;  WANG Can-cai;  WANG Qing-fu;  CAO Lan?鄢

College of Polymer Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, China

关键词:

聚法尼烯; 水相自由基聚合; 交联剂; 分子动力学模拟; 玻璃化转变温度; 力学性能

Keywords:

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分类号:

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DOI:

DOI:10.19908/j.cnki.ISSN1000-1255.2024.06.0507

文献标识码:

-

摘要:

以生物发酵获得的法尼烯为单体，通过水相自由基聚合制备了一种具有独特长侧链结构和特殊热性能的“瓶刷状”聚合物端羟基聚法尼烯（PFD）；利用Materials Studio对PFD和聚法尼烯（PF）进行分子动力学模拟，计算其玻璃化转变温度（Tg）、内聚能密度、自由体积等关键性能参数，并通过对比模拟结果与实验测试值对其Tg进行了验证。另外，使用多官能度异氰酸酯（牌号N 100）交联剂对PFD进行固化，并通过交联脚本评估其力学性能。结果表明，反式-1，4-PFD的Tg为231 K，与差示扫描量热法测得的Tg（226 K）较为相近。与N 100硫化体系交联后，PFD的力学性能显著提高。当未发生交联反应时，PFD的弹性模量为1.03 GPa，剪切模量为0.39 GPa；当其与N 100发生交联反应且交联密度达到73%时，PFD的交联三维网络弹性模量提高至21.12 GPa，剪切模量也提高至8.19 GPa，二者分别增加了1 950%和2 000%。

Abstract:

Farnesene monomer, obtained through the bio-fermentation, offered a unique long side chain structure that served as an excellent platform for the synthesis of “bottlebrush-like” polymers with exceptional thermal properties. Such polymers had immense potential in the production of polyurethane elastomers and adhesives. Hydroxyl-terminated polyfarnesene (PFD), which was safe, environmentally-friendly and pollution-free, was synthesized with farnesene as the monomer and industrial grade product hydrogen peroxide as the initiator by aqueous free-radical polymerization. Molecular dynamics (MD) simulations of PFD and polyfarnesene (PF) were performed using Materials Studio to calculate pivotal performance parameters, such as glass transition temperature (Tg), cohesive energy density (CED) and free volume. Tg was verified by comparing the results from the simulations with measured values obtained through experimental tests. Additionally, PFD was cured with multi-isocyanate (brand N 100) crosslinking agent, using a crosslinking script, to evaluate its mechanical characteristics.　As showed in Table 1, the results from the simulation of trans-1,4-PFD exhibited a Tg of 231 K, which was in close agreement with Tg (226 K) obtained from differential scanning calorimetry measurements. These findings demonstrated the usefulness of MD simulations in providing a thorough qualitative and quantitative understanding of the intricate connection between the properties and structure of polymers. The lower Tg of PFD indicated its excellent low-temperature performance. The trans-structure in the PFD system had good symmetry, stable structure and tight arrangement, which hindered the movement of its molecular chains. The Tg of 3,4-PFD was significantly higher than those of cis-1,4- and trans-1,4- structures, this was because the main chain of 3,4-PFD was shorter, and there was no isolated double bond in the molecular chain, reducing the flexibility of the molecular chain. The cohesive energy of a material was closely related to its intermolecular interaction. In the case of PF, the non-polar alkyl side chain provided a flexible sheath around the long-chain molecules, reducing the obstruction caused by the surrounding medium to the long-range movement of the molecular chain, weakening the intermolecular interaction, and lowering the CED. In polymers, the parameter free volume represented the volume expansion property and described the molecular motion amplitude. The simulation results presented in table 1 demonstrated that the free volume of 3,4-PFD was significantly smaller than 1,4-PFD. This could be attributed to the relatively low flexibility of the 3,4-structure that limited the molecular motion amplitude, which resulted in a smaller free volume.Table 1 Simulation parameters of different PF and PFD structures■　Moreover, the mechanical properties of PFD were significantly improved through the crosslinking with the N 100 vulcanization system. In the absence of crosslinking reaction, the elastic modulus of PFD was 1.03 GPa and shear modulus was 0.39 GPa. When the crosslinking reaction occured with N 100 and the crosslinking density reached up to 73%, the elastic modulus of the crosslinked three-dimensional network of PFD increased to 21.12 GPa, while the shear modulus rised to 8.19 GPa, representing the increases by 1 950% and 2 000%, respectively.

参考文献/References

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备注/Memo

备注/Memo:

Supported by National Natural Science Foundation of China (52403096).

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更新日期/Last Update: 1900-01-01