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

期数:

2024年4期

页码:

347

栏目:

出版日期:

1900-01-01

文章信息/Info

Title:

Efficient in-situ end-functionalization of polydienes by isothiocyanate via neodymium mediated coordinative chain transfer polymerization system

文章编号:

1000-1255（2024）04-0342-05

作者:

张秀慧1; 董 静2; 王 凤1; 刘 恒1; 张学全

1. 青岛科技大学 高分子科学与工程学院/山东省橡胶材料科学与工程高校实验室，山东 青岛 266042；2.中国石油石油化工研究院 兰州化工研究中心，兰州 730060

Author(s):

ZHANG Xiu-hui1;  DONG Jing2;  WANG Feng1;  LIU Heng1?鄢;  ZHANG Xue-quan1

1. Shandong Provincial College Laboratory of Rubber Material and Engineering/School of Polymer Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, China; 2. Lanzhou Petrochemical Research Center, Petrochemical Research Institute, PetroChina, Lanzhou 730060, China

关键词:

配位链转移聚合; 稀土顺丁橡胶; 末端官能化; 硫代异氰酸酯; 亲水性能

Keywords:

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分类号:

-

DOI:

DOI:10.19908/j.cnki.ISSN1000-1255.2024.04.0347

文献标识码:

-

摘要:

采用Nd(vers)3/Al(i-Bu)2H/SiMe2Cl2稀土配位可逆链转移体系催化共轭二烯烃聚合，利用其活性链末端η1-allylc-Al与硫代异氰酸酯高活性的特点，高效制备了末端官能化的聚共轭二烯烃产物。官能化试剂PDITC对整体聚合行为没有影响，且根据核磁共振氢谱计算，官能化产率均高达100%。官能化之后的聚合物具有较小的水接触角，证明其亲水性能得到明显改善。

Abstract:

End-functionalization of polydiene rubbers can not only improve its compatibility with inorganic fillers, but also enhance the overall mechanical properties. Nevertheless, for traditional neodymium (Nd) diene polymerization systems, it is highly challenging to achieve such end-functionalizations, because most of polydienyl chains are capped with η3-allyl-Nd moiety during the end of polymerization, which shows very poor reactivity with nucleophile compounds. We launched a new diene polymerization strategy calling coordinative chain transfer polymerization (CCTP)［1］. In such a system, all the polydienyl chains are capped with η1-allyl-Al moieties, which reveal greater reactivity with cyclic esters and epoxide compounds, providing an effective manner to prepare polydiene-polyester amphiphilic block copolymers. Inspired by such findings, we now show herein how such types of chain-ends react with isot-hiocyanate to demonstrate an efficient in-situ manner to access end-functionalized polydienes by using CCTP.　Among all the isothiocyanate compounds, 1,4-phenylene diisothiocyanate (PDITC) turns to the final choice, because besides high reactivity, it can also (i) generate thioamide —NH—C(■S)— functional groups that can form intermolecular hydrogen bonds, being similar to protein moieties in natural rubber; (ii) have two isothiocyanate groups, with one being inserted into η1-allyl-Al chain-end and the other undergoing ethanolysis/hydrolysis to generate another functional moiety. Subsequent end-functionalization studies were commenced by promoting polymerization of three types of diene monomers, including 1,3-butadiene (Bd), isoprene (Ip), and myrcene (My), by using a Nd-mediated CCTP system of Nd(vers)3/Al(i-Bu)2H/SiMe2Cl2, and then in-situ adding 40 equivalents of PDITC. As the data summarized in Table 1, adding PDITC in the end of the reaction posed little influence on the whole polymerization process as revealed from the narrow molecular weight distributions (polydispersity index (PDI) 1.57-1.73) as well as the high atom economies (3.8-4.8 polymer chains can be produced per Nd atom), as in previously reported CCTP systems［2-3］. Successful incorporation of PDITC molecules can be clearly identified from 1H-NMR spectra (Fig 1), in which resonance peaks of methylene proton, that is ascribed to the lastly inserted diene monomer, in the —CH2 unit can be clearly found at chemical shift 2.67, 2.70 and 2.71 for PBd, PIp and PMy respectively. The end-functionalization efficiency can be determined by its integral area with in-chain diene monomer units, giving 100% efficiencies in all three cases, demonstrating the high reactivity of isothiocyanate with η1-allyl-Al chain-end as expected.Table 1 In-situ end-functionalization by PDITC in Nd-mediated CCTP of diene monomer*■ * Polymerization conditions: ［Bd］/［Nd(vers)3］ 200, ［Al(i-Bu)2H］/［Nd］ 25, ［SiMe2Cl2］/［Nd(vers)3］ 1, n-hexane, 50 ℃, 4 h, ［PDITC］/［Nd(vers)3］ 40. ** Number of polymer chains produced by per Nd atom.■Fig 1 1H-NMR spectra of end-functionalized PBd, PIp and PMy　End-functionalized polydienes by PDITC performed much improved surfaces properties, as indicated from the obviously reduced static water contact angles from 94.3° and 100.1° for unfunctionalized PBd and PMy to 85.5° and 89.2° for functionalized counterparts, respectively (Fig 2).

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更新日期/Last Update: 1900-01-01