JoVE Journal > Chemistry
Summary
Abstract
Introduction
Protocol
Results
Discussion
Disclosures
Acknowledgements
Materials
References
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화학

乙烯聚合中使用并联电抗器的压力和链转移聚合的动力学分析

Published: November 27, 2015
doi:
10.3791/53212
,
1Department of Chemistry,University of Minnesota – Twin Cities

Summary

一种协议，用于聚合催化剂，链转移聚合，聚乙烯表征和反应动力学分析的高通量分析，提出。

Abstract

我们证明高通量催化剂使用平行压力反应器由镍α-二亚胺乙烯聚合催化剂的初始合成起始筛选的方法。初始聚合用催化剂导致优化的反应条件，包括催化剂浓度，乙烯压力和反应时间。使用气体摄取数据用于这些反应的，一个过程来计算传播（K p）的初始速率呈现。使用优化的条件下，镍α二亚胺聚合催化剂的能力乙烯聚合期间经历与二乙基锌（ZnEt 2）链转移进行了研究。的过程来评估催化剂的经过链转移（从分子量和 13 C NMR数据），计算链转移的程度，并计算链转移速率（K e）中呈现的能力。

Introduction

聚烯烃工业的聚合物与用于热塑性塑料和弹性体的一类重要的。在单点催化剂生产聚烯烃的设计显著进步导致了能够调整分子量，多分散性，和聚合物微结构，这导致了广泛的潜在应用。1-3最近，链转移和链穿梭聚合已经开发，得到附加路由来修改聚合物的性能而无需修改该催化剂。4-6该系统使用单中心过渡金属催化剂和链转移试剂（CTR），它通常是主族金属烷基。在此聚合中，正在生长的聚合物链是能够从催化剂的点击率，其中聚合物链保持休眠，直到它被转移回催化剂转移。同时，被转移到催化剂的烷基可以发起肛疗法聚合物链。在链转移聚合，一种催化剂可以启动一个更大数量的链相对于标准催化聚合。聚合物链终止，该链转移金属;因此，进一步的端基功能化是可能的。该系统可用于改变分子量和聚烯烃的分子量分布，7催化上主族金属，第8和涉及multicatalyst系统，如嵌段共聚物特种聚合物的合成Aufbau状烷基链的增长。9， 10

链转移聚合已观察到最常见的与前过渡金属（铪，锆）和烷基锌或烷基铝试剂，尽管实施例在整个过渡金属系存在。5,7,8,11-16在典型的前过渡金属催化剂体系，链转移是快速，高效，可逆导致窄的分子量分布。章艾因传输/穿梭已中旬至下旬的过渡金属 （如铬，铁，钴和镍）与第2组和第12烷基金属，虽然比起早期的金属传输的速率变化很大。4,7被观察到， 17-19的两个主要因素是所需的必要的有效的链转移：具有良好的金属-碳键离解能匹配的聚合催化剂和链转移试剂，和合适的空间位阻环境以促进烷基桥连的双金属中间体双分子形成/破损20在后过渡金属的情况下，如果催化剂不包含足够的空间体积，β-氢化物（β-H）消除将是占主导地位的终止途径和一般会失竞争的链转移。

本文我们就从镍-2,3- butanediimine类催化剂体系通过SMA双金属链转移到锌的双（2,6-二甲基苯基）二乙基锌与（ZnEt 2）的研究报告LL-大规模高通量的反应。链转移将通过检查通过凝胶渗透色谱分析中的变化分子量（M w）的和所得到的聚乙烯的分散度指数来识别。链转移还将通过乙烯基的饱和链端作为链转移剂浓度的函数的比率的13 C NMR分析鉴定。传播和链转移的速率的深入动力学分析也将提交。

Protocol

注意：使用前请咨询所有相关的材料安全数据表（MSDS）。几个在这些合成中使用的化学物质是剧毒和致癌性，而几个是引火并点燃在空气中。执行这些反应包括利用工程控制（通风橱，手套箱）和个人防护装备时，请使用所有适当的安全措施（安全眼镜，手套，实验室外套，全长长裤，闭趾鞋）。下面的过程部分涉及标准的无空气的处理技术。 1.制备[双（2,6-二甲基苯基）-2,3…

Representative Results

乙烯气体消耗与时间的关系示于图1所测试的不同的乙烯压力。这个数据被用于确定优化的反应条件。乙烯气体消耗与时间的关系示于图2A中用于催化剂单独的样品，其中用于计算传播（K p）的速率。 图2B示出的凝胶渗透色谱（GPC）用于链转移聚合痕迹与0-1,000当量二乙基锌。 GPC的用于计算的聚合物样品，其示</stro…

Discussion

甲基取代的阳离子[α-二亚胺] NIBR 2 与MAO活化的乙烯聚合催化剂进行其能力为乙烯链转移聚合。将反应物通过气体吸收测量监测，以确定的速率和聚合和催化剂寿命的程度， 并通过凝胶渗透色谱（GPC）测定所获得的聚合物的分子量。最初，镍催化剂进行试验的范围内的乙烯压力（从15-225磅），以确定最佳条件为这个系统在不存在ZnEt 2。使用催化剂的3.33×1…

Disclosures

The authors have nothing to disclose.

Acknowledgements

财政支持由美国明尼苏达大学（启动资金）和ACS石油研究基金（54225-DNI3）提供。设备采购的化学系核磁共振设备通过来自美国国立卫生研究院（S10OD011952）的资助来自美国明尼苏达大学配套资金的支持。我们承认明尼苏达核磁共振中心为高温NMR。资助核磁共振仪器由副总统办公室的研究，医学院，生物科学，美国国立卫生研究院，美国国家科学基金会的学院和明尼苏达州医学基金会提供的。我们感谢约翰·沃尔泽（埃克森美孚）为PEEK高通量的搅拌桨的礼物。

Materials

Endeavor Pressure Reactor Biotage EDV-1N-L
Blade Impellers Biotage 900543
Glass Liners Biotage 900676
2,3-butanedione, 99% Alfa Aesar A14217
2,6-dimethylaniline, 99% Sigma Aldrich D146005
formic acid, 95% Sigma Aldrich F0507
methanol, 99.8% Sigma Aldrich 179337 ACS Reagent
nickel (II) bromide, 99% Strem 28-1140 anhydrous, hygroscopic
triethylorthoformate, 98% Sigma Aldrich 304050 dried with K2CO3 and distilled
1,2-dimethoxyethane, 99.5% Sigma Aldrich 259527 dried with Na/Benzophenone and distilled
pentane, 99% Fisher P399 HPLC Grade *
dichloromethane, 99.5% Fisher D37 ACS Reagent *
toluene, 99.8% Fisher T290 HPLC Grade *
methylaluminoxane Albemarle MAO pyrophoric, 30% in toluene
diethylzinc, 95% Strem 93-3030 pyrophoric
1,2,4-trichlorobenzene, 99% Sigma Aldrich 296104
1,1,2,2-tetrachloroethane-D2, 99.6% Cambridge Isotopes DLM-35
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Tags

Ethylene PolymerizationParallel Pressure ReactorHigh-throughput Catalyst ScreeningNickel α-diimine CatalystKinetic AnalysisChain Transfer PolymerizationDiethylzincPropagation Rate ConstantChain Transfer Rate Constant

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Hue, R. J., Tonks, I. A. Ethylene Polymerizations Using Parallel Pressure Reactors and a Kinetic Analysis of Chain Transfer Polymerization. J. Vis. Exp. (105), e53212, doi:10.3791/53212 (2015).
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