Name: Ethylene Polymerizations Using Parallel Pressure Reactors and a Kinetic Analysis of Chain Transfer Polymerization (Video) | JoVE Journal
Uploaded: 2015-11-27T13:00:00.000+00:00
Duration: 7 min 28 s
Description: Learn high-throughput ethylene polymerization methods for catalyst screening and kinetic analysis of chain transfer mechanisms. This protocol enables efficient assessment of polymerization catalysts across diverse reaction conditions.

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5 minutes

Financial support was provided by the University of Minnesota (start up funds) and the ACS Petroleum Research Fund (54225-DNI3). Equipment purchases for the Chemistry Department NMR facility were supported through a grant from the NIH (S10OD011952) with matching funds from the University of Minnesota. We acknowledge the Minnesota NMR Center for high-temperature NMR. Funding for NMR instrumentation was provided by the Office of the Vice President for Research, the Medical School, the College of Biological Science, NIH, NSF, and the Minnesota Medical Foundation. We thank John Walzer (ExxonMobil) for a gift of PEEK high-throughput stirring paddles.

Caution: Please consult all relevant material safety data sheets (MSDS) before use. Several of the chemicals used in these syntheses are acutely toxic and carcinogenic, while several are pyrophoric and ignite in air. Please use all appropriate safety practices when performing these reactions including the use of engineering controls (fume hood, glovebox) and personal protective equipment (safety glasses, gloves, lab coat, full length pants, closed-toe shoes). Portions of the following procedures involve standard air-free handling techniques.
1. Preparation of [bis(2,6-dimethylphenyl)-2,3-butanediimine]NiBr2,21-25
<ol>
	<li>Preparation of bis(2,6-dimethylphenyl)-2,3-butanediimine: (α-diimine)
	<ol>
		<li>Dissolve 2,3-butanedione (1.0 ml, 11 mmol) and 2,6-dimethylaniline (2.8 ml, 23 mmol) in 20 ml of methanol in a 100 ml round bottom flask.</li>
		<li>Add formic acid (0.4 ml, 11 mmol) and stir the reaction at room temperature until the diimine precipitates (typically 1-2 hr, but can be left overnight). If a precipitate does not form, concentrate the reaction mixture using a rotary evaporator and cool in an ice bath.</li>
		<li>Filter the reaction mixture using glass frit and filter flask and wash the yellow solid with 20 ml of cold methanol and dry in vacuo. 
		Note: 1H NMR (500 MHz, CD2Cl2): δ 7.06 (d, J = 7.6 Hz, 4H), 6.92 (t, J = 7.5 Hz, 2H), 2.00-1.99 (m, 19H).</li>
	</ol>
	</li>
	<li>Preparation of (1,2-dimethoxyethane)NiBr2: DME-NiBr2
	<ol>
		<li>Under a nitrogen atmosphere, combine anhydrous nickel bromide (NiBr2 , 15 g, 0.069 mol), triethylorthoformate (30 ml, 0.185 mol) and methanol (100 ml) in a 2-neck round-bottom flask fitted with a reflux condenser and rubber septum on a Schlenk line under a nitrogen atmosphere.</li>
		<li>Reflux the brown reaction mixture under a nitrogen atmosphere until a green solution forms. This typically takes 2-3 hr, however this reaction can be left refluxing overnight if necessary.</li>
		<li>After allowing the mixture to cool, concentrate the reaction mixture using the vacuum pump on the Schlenk line to form a dark green gel.</li>
		<li>Cannula transfer an excess 1,2-dimethoxyethane (DME, 100 ml) onto the green gel, which instantly forms orange solid. Once all the DME is added, heat the reaction at 85 °C for an additional 2 hr until a light orange reaction mixture forms. Cool the reaction to room temperature, at which point a light-orange solid precipitates.</li>
		<li>Remove the reflux condenser from the reaction flask and replace with a Schlenk frit connected to a second Schlenk receiving flask under a nitrogen atmosphere. Rotate the entire apparatus by 180° causing the orange reaction mixture to enter the Schlenk frit and filter the reaction mixture.</li>
		<li>Remove the original reaction flask and place a septum on the Schlenk frit. Cannula transfer DME (100 ml) and then pentane (100 ml) to wash the DME-NiBr2. Dry the orange solid in vacuo and bring into the glovebox. 
		Note: DME-NiBr2 can be stored indefinitely under a nitrogen atmosphere at room temperature. When left open to the atmosphere, it forms a green, hydrated gel.</li>
	</ol>
	</li>
	<li>Preparation of [bis(2,6-dimethylphenyl)-2,3-butanediimine]NiBr2: ([α-diimine]NiBr2)
	<ol>
		<li>In the glovebox, combine DME-NiBr2 (1.0 g, 3.2 mmol) and bis(2,6-dimethylphenyl)-2,3-butanediimine (1.1 g, 3.8 mmol) in a 50 ml round bottom flask.</li>
		<li>Add 20 ml of dichloromethane and stir overnight at room temperature.</li>
		<li>Filter the reaction mixture with a glass frit and filter flask. Wash the brown solid with 75 ml of dichloromethane and dry in vacuo. 
		Note: This nickel catalyst can be stored indefinitely in an inert-atmosphere glovebox at room temperature. It is also insoluble in most solvents, so standard characterizations were not performed.</li>
	</ol>
	</li>
</ol>
2. Preparation of Catalytic Stock Solutions
<ol>
	<li>Preparation of [[α-diimine]Ni(CH3)]+ [MAO]- stock solution
	<ol>
		<li>Prepare a 1.0 x 10-3 M catalyst stock solution by adding 0.0041 g of [α-diimine]NiBr2 (8.0 x 10-6 mol) into a vial with 7.5 ml of toluene.</li>
		<li>To the stirred nickel suspension, add 0.50 ml of 30% methylaluminoxane (MAO) in toluene and stir for 1 min. The color will change from a brown suspension to a blue-green solution. This solution can be stored at -30 °C for up to 6 hr and used in subsequent polymerizations. 
		Note: Methylaluminoxane is pyrophoric and will smoke in air. It should only be used in an inert-atmosphere glovebox and care should be taken when removing contaminated syringes/glassware from the glovebox. Typically, the syringes and glassware are washed with toluene in the glovebox and placed in a metal can, separate from Kimwipes or any other flammable substances. The contaminated toluene is capped in a vial and removed from the glovebox with the metal can. These items are transferred to the fume hood where they open to air and allowed to slowly quench behind the protective glass.</li>
	</ol>
	</li>
	<li>Preparation of ZnEt2 stock solution
	<ol>
		<li>Prepare a 1.2 M solution by dissolving 0.25 ml of ZnEt2 in 1.75 ml toluene. 
		Note: Diethylzinc is pyrophoric and will ignite in air. It should only be used in an inert atmosphere glovebox and care should be taken when removing contaminated syringes/glassware from the glovebox. Typically, the syringes and glassware are washed with toluene in the glovebox and placed in a metal can, separate from Kimwipes or any other flammable substances. The contaminated toluene is capped in a vial and removed from the glovebox with the metal can. These items are transferred to the fumehood where they open to air and allowed to slowly quench behind the protective glass.</li>
	</ol>
	</li>
</ol>
3. Catalytic Polymerizations Using a Parallel Pressure Reactor
<ol>
	<li>Pressure Scope
	<ol>
		<li>Set up all polymerization reactions in a parallel pressure reactor with overhead stirring housed in an N2 atmosphere glovebox. Program the polymerization in the software: indicate total reaction volume (3.0 ml), the purge gas (N2), the desired reaction gas (ethylene), the desired pressure (15-150 psi), and the desired reaction time (1 hr). 
		Note: A Biotage Endeavor Parallel Pressure Reactor with a separate computer capable of monitoring the gas uptake was used for polymerizations. All polymerizations were done at least three times to ensure accuracy and reproducibility. Using this type of reactor several variables can be adjusted within a single experiment or over the course of multiple experiments including: the reaction gases, pressure, temperature, time, solvent, volume, catalyst, or chain transfer reagent. By doing eight reactions at a time with real-time gas uptake, catalytic reactions are efficiently tested. In this case, the reaction vials have a maximum volume of 5 ml, therefore a volume of 3 ml was chosen to account for the formation of polymer. Also, standard concentrations, pressures and times were based of literature conditions.21 These polymerizations can all be done in individual pressure reactors or even on a Schlenk line, however it is more difficult to achieve higher pressures or gas uptake for the reactions.</li>
		<li>Insert glass liner reaction vials into the eight wells. Use the depth tool to ensure the glass liners are at the appropriate height. Insert the blade impellers into the overhead assembly.</li>
		<li>Fill the reaction vials according to Table 1:
		<table border="0" cellpadding="0" cellspacing="0">
			<tbody>
				<tr>
					<td>Reaction Vessel</td>
					<td>Pressure (psi)</td>
					<td>Catalyst Vol. (ml)</td>
					<td>ZnEt2 Vol. (ml)</td>
					<td>Toluene Vol. (ml)</td>
				</tr>
				<tr>
					<td>1</td>
					<td>15</td>
					<td>0</td>
					<td>0</td>
					<td>3</td>
				</tr>
				<tr>
					<td>2</td>
					<td>15</td>
					<td>0.1</td>
					<td>0</td>
					<td>2.9</td>
				</tr>
				<tr>
					<td>3</td>
					<td>30</td>
					<td>0</td>
					<td>0</td>
					<td>3</td>
				</tr>
				<tr>
					<td>4</td>
					<td>30</td>
					<td>0.1</td>
					<td>0</td>
					<td>2.9</td>
				</tr>
				<tr>
					<td>5</td>
					<td>60</td>
					<td>0</td>
					<td>0</td>
					<td>3</td>
				</tr>
				<tr>
					<td>6</td>
					<td>60</td>
					<td>0.1</td>
					<td>0</td>
					<td>2.9</td>
				</tr>
				<tr>
					<td>7</td>
					<td>150</td>
					<td>0</td>
					<td>0</td>
					<td>3</td>
				</tr>
				<tr>
					<td>8</td>
					<td>150</td>
					<td>0.1</td>
					<td>0</td>
					<td>2.9</td>
				</tr>
			</tbody>
		</table>
		Table 1. Reaction conditions for the pressure scope reactions.</li>
		<li>Ensure the O-rings are properly seated in the metal grooves and carefully place the overhead stirring assembly on the base and screw down in an alternating fashion. Ensure all screws are tight and press start in the software. Monitor the reaction via gas uptake measurements.</li>
		<li>After 1 hr of polymerization, remove the reaction vials from the glove box and precipitate polyethylene with the addition of 5% hydrochloric acid in methanol, remove solvent and dry in vacuo. Mass the polymer to obtain the yield and compare to the ethylene consumption during the reaction.</li>
		<li>Calculate the activity of the catalyst, which is the mass of polymer formed per mole of catalyst, per hour of polymerization.</li>
		<li>Analyze the molecular weight and dispersity index of the dried polyethylene using high temperature Gel Permeation Chromatography (GPC). Dissolve 0.002 g of the polymer in 2 ml 1,2,4-trichlorobenzene at 135 °C. Run the GPC according to manufacturer's protocol. 
		Note: An Agilent PL-GPC 220 High Temperature GPC/SEC system was used at 135 °C and data was fit using polystyrene standards to analyze the molecular weight of the polymer.</li>
		<li>Analyze the degree of branching, the branch type and the end group type of the dried polyethylene using high-temperature 13C NMR. Dissolve 0.050-0.080 g of the polymer in 0.5 ml of tetrachloroethane-d2 (C2D2Cl4) at 130 °C. Run the samples on a 600 MHz NMR at 130 °C for at least 2,000 scans. Assign polymer branching according to the literature.26-28 
		Note: An Agilent/Varian 600 MHz spectrometer at 130 °C was used for 13C NMR analysis.</li>
	</ol>
	</li>
	<li>Chain Transfer Polymerization
	<ol>
		<li>Following the same procedures and analysis as Section 3.1, fill the reactor and program the software according to the parameters in Table 2:
		<table border="0" cellpadding="0" cellspacing="0">
			<tbody>
				<tr>
					<td>Reaction Vessel</td>
					<td>Pressure (psi)</td>
					<td>Catalyst Vol. (ml)</td>
					<td>ZnEt2 Vol. (ml)</td>
					<td>Toluene Vol. (ml)</td>
				</tr>
				<tr>
					<td>1</td>
					<td>60</td>
					<td>0.1</td>
					<td>0</td>
					<td>2.9</td>
				</tr>
				<tr>
					<td>2</td>
					<td>60</td>
					<td>0.1</td>
					<td>0.005</td>
					<td>2.9</td>
				</tr>
				<tr>
					<td>3</td>
					<td>60</td>
					<td>0.1</td>
					<td>0.01</td>
					<td>2.89</td>
				</tr>
				<tr>
					<td>4</td>
					<td>60</td>
					<td>0.1</td>
					<td>0.015</td>
					<td>2.89</td>
				</tr>
				<tr>
					<td>5</td>
					<td>60</td>
					<td>0.1</td>
					<td>0.025</td>
					<td>2.88</td>
				</tr>
				<tr>
					<td>6</td>
					<td>60</td>
					<td>0.1</td>
					<td>0.042</td>
					<td>2.86</td>
				</tr>
				<tr>
					<td>7</td>
					<td>60</td>
					<td>0.1</td>
					<td>0.06</td>
					<td>2.84</td>
				</tr>
				<tr>
					<td>8</td>
					<td>60</td>
					<td>0.1</td>
					<td>0.085</td>
					<td>2.82</td>
				</tr>
			</tbody>
		</table>
		Table 2. Reaction conditions for the chain transfer polymerization reactions.</li>
		<li>In addition, calculate the moles of chains extended due to the presence of ZnEt2 and the number of chains initiated per mole of catalyst based on the following equations.7 
		<img alt="Polymer yield equations for catalysis process analysis, showing formula relationships." src="/files/ftp_upload/53212/53212eq1-2.jpg" width="250" data-altupdatedat="1787630408000" data-alt="Equation 1"> 
		(M-R)Extended - moles of chains extended due to the presence of ZnEt2 (mol) 
		YieldPolymer - Mass of polymer formed (g) 
		Mn - Number average molecular weight of the polymer from GPC (g/mol) 
		Chainsinitiated - Number of chains initiated per mole of catalyst 
		Molescatalyst - Moles of catalyst used in the polymerization</li>
		<li>Make a plot of the number chains initiated versus the concentration of ZnEt2.</li>
	</ol>
	</li>
</ol>
4. Kinetic Analysis of Polymerizations: Rates of Chain Transfer and Propagation
<ol>
	<li>Rate of Propagation (kp)
	<ol>
		<li>For each run where only [α-diimine]NiBr2 is present, make a plot of ethylene consumption versus time.</li>
		<li>Fit the initial ethylene gas uptake in the linear region to obtain the initial rate. In the case of Figure 2a, the traces were fit from 500 to 2,000 sec.</li>
		<li>Use the average of the slopes to obtain the rate of propagation (kp) for the particular catalyst at the desired pressure.</li>
	</ol>
	</li>
	<li>Rate of chain transfer (kp)
	<ol>
		<li>Estimate the concentration of ethylene, [C2=], in 3.0 ml of toluene from the average gas uptake (solubility) by finding the number of moles of gas consumed in the reactors that do not contain catalyst.</li>
		<li>Make a Mayo plot of 1/Mn (from the molecular weight data obtained from the GPC) versus [ZnRx]/[C2=] (from the concentration of ZnEt2 placed in the reactor).7, 29</li>
		<li>Fit the data to a linear line based on the Mayo equation. Multiply the slope by 28, the molecular weight of ethylene, to obtain the ratio of the rate of chain transfer to the rate of propagation (ke/kp). 
		<img alt="Polymerization kinetics equation, formula for molecular weight (1/Mn=1/Mn0+ke[ZnRx]/kp28[C2])." src="/files/ftp_upload/53212/53212eq3.jpg" width="230" data-altupdatedat="1787630408000" data-alt="Equation 3"> 
		MN - Number average molecular weight of the polymer from GPC with ZnEt2 
		MNo - Number average molecular weight of the polymer from GPC without ZnEt2 
		ke - Rate of chain transfer 
		kp - Rate of propagation 
		[ZnRx] - Concentration of ZnEt2 in the reaction 
		[C2=] - Concentration of ethylene in the reaction 
		28 - The molecular weight of ethylene</li>
		<li>Multiply ke/kp by kp obtained in the previous section to get the rate of chain transfer ke.</li>
	</ol>
	</li>
</ol>

<ol><li>Gibson, V. C., Spitzmesser, S. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Advances+in+Non-Metallocene+Olefin+Polymerization+Catalysis%5BTitle%5D)+AND+%22Chem.+Rev%22%5BJournal%5D)">Advances in Non-Metallocene Olefin Polymerization Catalysis.</a> Chem. Rev. 103 (1), 283-316 (2002).</li>
<li>Coates, G. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Precise+Control+of+Polyolefin+Stereochemistry+Using+Single-Site+Metal+Catalysts%5BTitle%5D)+AND+%22Chem.+Rev%22%5BJournal%5D)">Precise Control of Polyolefin Stereochemistry Using Single-Site Metal Catalysts.</a> Chem. Rev. 100 (4), 1223-1252 (2000).</li>
<li>Resconi, L., Cavallo, L., Fait, A., Piemontesi, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Selectivity+in+Propene+Polymerization+with+Metallocene+Catalysts%5BTitle%5D)+AND+%22Chem.+Rev%22%5BJournal%5D)">Selectivity in Propene Polymerization with Metallocene Catalysts.</a> Chem. Rev. 100 (4), 1253-1346 (2000).</li>
<li>Valente, A., Mortreux, A., Visseaux, M., Zinck, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Coordinative+Chain+Transfer+Polymerization%5BTitle%5D)+AND+%22Chem.+Rev%22%5BJournal%5D)">Coordinative Chain Transfer Polymerization.</a> Chem. Rev. 113 (5), 3836-3857 (2013).</li>
<li>Sita, L. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Ex+Uno+Plures+%28%26%2334%3BOut+of+One%2C+Many%26%2334%3B%29%3A+New+Paradigms+for+Expanding+the+Range+of+Polyolefins+through+Reversible+Group+Transfers%5BTitle%5D)+AND+%22Angew.+Chem.%2C+Int.+Ed%22%5BJournal%5D)">Ex Uno Plures (&#34;Out of One, Many&#34;): New Paradigms for Expanding the Range of Polyolefins through Reversible Group Transfers.</a> Angew. Chem., Int. Ed. 48 (14), 2464-2472 (2009).</li>
<li>Kempe, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((How+to+Polymerize+Ethylene+in+a+Highly+Controlled+Fashion%3F%5BTitle%5D)+AND+%22Chem.+Eur.+J%22%5BJournal%5D)">How to Polymerize Ethylene in a Highly Controlled Fashion?</a> Chem. Eur. J. 13 (10), 2764-2773 (2007).</li>
<li>van Meurs, M., Britovsek, G. J. P., Gibson, V. C., Cohen, S. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Polyethylene+Chain+Growth+on+Zinc+Catalyzed+by+Olefin+Polymerization+Catalysts%3A+A+Comparative+Investigation+of+Highly+Active+Catalyst+Systems+across+the+Transition+Series%5BTitle%5D)+AND+%22J.+Am.+Chem.+Soc%22%5BJournal%5D)">Polyethylene Chain Growth on Zinc Catalyzed by Olefin Polymerization Catalysts: A Comparative Investigation of Highly Active Catalyst Systems across the Transition Series.</a> J. Am. Chem. Soc. 127 (27), 9913-9923 (2005).</li>
<li>Wei, J., Zhang, W., Sita, L. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Aufbaureaktion+Redux%3A+Scalable+Production+of+Precision+Hydrocarbons+from+AlR3+%28R%3DEt+or+iBu%29+by+Dialkyl+Zinc+Mediated+Ternary+Living+Coordinative+Chain-Transfer+Polymerization%5BTitle%5D)+AND+%22Angew.+Chem.%2C+Int.+Ed%22%5BJournal%5D)">Aufbaureaktion Redux: Scalable Production of Precision Hydrocarbons from AlR3 (R=Et or iBu) by Dialkyl Zinc Mediated Ternary Living Coordinative Chain-Transfer Polymerization.</a> Angew. Chem., Int. Ed. 49 (10), 1768-1772 (2010).</li>
<li>Arriola, D. J., Carnahan, E. M., Hustad, P. D., Kuhlman, R. L., Wenzel, T. T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Catalytic+Production+of+Olefin+Block+Copolymers+via+Chain+Shuttling+Polymerization%5BTitle%5D)+AND+%22Science%22%5BJournal%5D)">Catalytic Production of Olefin Block Copolymers via Chain Shuttling Polymerization.</a> Science. 312 (5774), 714-719 (2006).</li>
<li>Mazzolini, J., Espinosa, E., D'Agosto, F., Boisson, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Catalyzed+chain+growth+%28CCG%29+on+a+main+group+metal%3A+an+efficient+tool+to+functionalize+polyethylene%5BTitle%5D)+AND+%22Polymer+Chemistry%22%5BJournal%5D)">Catalyzed chain growth (CCG) on a main group metal: an efficient tool to functionalize polyethylene.</a> Polymer Chemistry. 1 (6), 793-800 (2010).</li>
<li>Britovsek, G. J. P., Cohen, S. A., Gibson, V. C., van Meurs, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Iron+Catalyzed+Polyethylene+Chain+Growth+on+Zinc%3A+A+Study+of+the+Factors+Delineating+Chain+Transfer+versus+Catalyzed+Chain+Growth+in+Zinc+and+Related+Metal+Alkyl+Systems%5BTitle%5D)+AND+%22J.+Am.+Chem.+Soc%22%5BJournal%5D)">Iron Catalyzed Polyethylene Chain Growth on Zinc: A Study of the Factors Delineating Chain Transfer versus Catalyzed Chain Growth in Zinc and Related Metal Alkyl Systems.</a> J. Am. Chem. Soc. 126 (34), 10701-10712 (2004).</li>
<li>Gibson, V. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Shuttling+Polyolefins+to+a+New+Materials+Dimension%5BTitle%5D)+AND+%22Science%22%5BJournal%5D)">Shuttling Polyolefins to a New Materials Dimension.</a> Science. 312 (5774), 703-704 (2006).</li>
<li>Chenal, T., Olonde, X., Pelletier, J. -F., Bujadoux, K., Mortreux, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Controlled+polyethylene+chain+growth+on+magnesium+catalyzed+by+lanthanidocene%3A+A+living+transfer+polymerization+for+the+synthesis+of+higher+dialkyl-magnesium%5BTitle%5D)+AND+%22Polymer%22%5BJournal%5D)">Controlled polyethylene chain growth on magnesium catalyzed by lanthanidocene: A living transfer polymerization for the synthesis of higher dialkyl-magnesium.</a> Polymer. 48 (7), 1844-1856 (2007).</li>
<li>Busico, V., Cipullo, R., Chadwick, J. C., Modder, J. F., Sudmeijer, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Effects+of+Regiochemical+and+Stereochemical+Errors+on+the+Course+of+Isotactic+Propene+Polyinsertion+Promoted+by+Homogeneous+Ziegler-Natta+Catalysts%5BTitle%5D)+AND+%22Macromolecules%22%5BJournal%5D)">Effects of Regiochemical and Stereochemical Errors on the Course of Isotactic Propene Polyinsertion Promoted by Homogeneous Ziegler-Natta Catalysts.</a> Macromolecules. 27 (26), 7538-7543 (1994).</li>
<li>Annunziata, L., Duc, M., Carpentier, J. -F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Chain+Growth+Polymerization+of+Isoprene+and+Stereoselective+Isoprene-Styrene+Copolymerization+Promoted+by+an+ansa-Bis%28indenyl%29allyl-Yttrium+Complex%5BTitle%5D)+AND+%22Macromolecules%22%5BJournal%5D)">Chain Growth Polymerization of Isoprene and Stereoselective Isoprene-Styrene Copolymerization Promoted by an ansa-Bis(indenyl)allyl-Yttrium Complex.</a> Macromolecules. 44 (18), 7158-7166 (2011).</li>
<li>Kretschmer, W. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Reversible+Chain+Transfer+between+Organoyttrium+Cations+and+Aluminum%3A+Synthesis+of+Aluminum-Terminated+Polyethylene+with+Extremely+Narrow+Molecular-Weight+Distribution%5BTitle%5D)+AND+%22Chem.+Eur.+J%22%5BJournal%5D)">Reversible Chain Transfer between Organoyttrium Cations and Aluminum: Synthesis of Aluminum-Terminated Polyethylene with Extremely Narrow Molecular-Weight Distribution.</a> Chem. Eur. J. 12 (35), 8969-8978 (2006).</li>
<li>Britovsek, G. J. P., Cohen, S. A., Gibson, V. C., Maddox, P. J., van Meurs, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Iron-Catalyzed+Polyethylene+Chain+Growth+on+Zinc%3A+Linear+%CE%B1-Olefins+with+a+Poisson+Distribution%5BTitle%5D)+AND+%22Angew.+Chem.%2C+Int.+Ed%22%5BJournal%5D)">Iron-Catalyzed Polyethylene Chain Growth on Zinc: Linear α-Olefins with a Poisson Distribution.</a> Angew. Chem., Int. Ed. 41 (3), 489-491 (2002).</li>
<li>Xiao, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+Novel+Linear-Hyperbranched+Multiblock+Polyethylene+Produced+from+Ethylene+Monomer+Alone+via+Chain+Walking+and+Chain+Shuttling+Polymerization%5BTitle%5D)+AND+%22Macromolecules%22%5BJournal%5D)">A Novel Linear-Hyperbranched Multiblock Polyethylene Produced from Ethylene Monomer Alone via Chain Walking and Chain Shuttling Polymerization.</a> Macromolecules. 42 (6), 1834-1837 (2009).</li>
<li>Simon, L. C., Mauler, R. S., De Souza, R. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Effect+of+the+alkylaluminum+cocatalyst+on+ethylene+polymerization+by+a+nickel-diimine+complex%5BTitle%5D)+AND+%22J.+Polym.+Sci.+A+Polym+Chem%22%5BJournal%5D)">Effect of the alkylaluminum cocatalyst on ethylene polymerization by a nickel-diimine complex.</a> J. Polym. Sci. A Polym Chem. 37 (24), 4656-4663 (1999).</li>
<li>Hue, R. J., Cibuzar, M. P., Tonks, I. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Analysis+of+Polymeryl+Chain+Transfer+Between+Group+10+Metals+and+Main+Group+Alkyls+during+Ethylene+Polymerization%5BTitle%5D)+AND+%22ACS+Catalysis%22%5BJournal%5D)">Analysis of Polymeryl Chain Transfer Between Group 10 Metals and Main Group Alkyls during Ethylene Polymerization.</a> ACS Catalysis. 4 (11), 4223-4231 (2014).</li>
<li>Johnson, L. K., Killian, C. M., Brookhart, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((New+Pd%28II%29-+and+Ni%28II%29-Based+Catalysts+for+Polymerization+of+Ethylene+and+.alpha.-Olefins%5BTitle%5D)+AND+%22J.+Am.+Chem.+Soc%22%5BJournal%5D)">New Pd(II)- and Ni(II)-Based Catalysts for Polymerization of Ethylene and .alpha.-Olefins.</a> J. Am. Chem. Soc. 117 (23), 6414-6415 (1995).</li>
<li>Ittel, S. D., Johnson, L. K., Brookhart, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Late-Metal+Catalysts+for+Ethylene+Homo-+and+Copolymerization%5BTitle%5D)+AND+%22Chem.+Rev%22%5BJournal%5D)">Late-Metal Catalysts for Ethylene Homo- and Copolymerization.</a> Chem. Rev. 100 (4), 1169-1204 (2000).</li>
<li>Bautista, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Synthesis+and+Diels-Alder+Cycloadditions+of+exo-Imidazolidin-2-one+Dienes%5BTitle%5D)+AND+%22J.+Org.+Chem%22%5BJournal%5D)">Synthesis and Diels-Alder Cycloadditions of exo-Imidazolidin-2-one Dienes.</a> J. Org. Chem. 76 (19), 7901-7911 (2011).</li>
<li>Rulke, R. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((NMR+study+on+the+coordination+behavior+of+dissymmetric+terdentate+trinitrogen+ligands+on+methylpalladium%28II%29+compounds%5BTitle%5D)+AND+%22Inorg.+Chem%22%5BJournal%5D)">NMR study on the coordination behavior of dissymmetric terdentate trinitrogen ligands on methylpalladium(II) compounds.</a> Inorg. Chem. 32 (25), 5769-5778 (1993).</li>
<li>Ward, L. G. L., Pipal, J. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Anhydrous+Nickel+%28II%29+Halides+and+their+Tetrakis+%28Ethanol%29+and+1%2C2-Dimethoxyethane+Complexes%5BTitle%5D)+AND+%22Inorg.+Syntheses%22%5BJournal%5D)">Anhydrous Nickel (II) Halides and their Tetrakis (Ethanol) and 1,2-Dimethoxyethane Complexes.</a> Inorg. Syntheses. 13, 154-164 (1972).</li>
<li>Galland, G. B., de Souza, R. F., Mauler, R. S., Nunes, F. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((13C+NMR+Determination+of+the+Composition+of+Linear+Low-Density+Polyethylene+Obtained+with+%5B%CE%B73-Methallyl-nickel-diimine%5DPF6+Complex%5BTitle%5D)+AND+%22Macromolecules%22%5BJournal%5D)">13C NMR Determination of the Composition of Linear Low-Density Polyethylene Obtained with [η3-Methallyl-nickel-diimine]PF6 Complex.</a> Macromolecules. 32 (5), 1620-1625 (1999).</li>
<li>Cotts, P. M., Guan, Z., McCord, E., McLain, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Novel+Branching+Topology+in+Polyethylenes+As+Revealed+by+Light+Scattering+and+13C+NMR%5BTitle%5D)+AND+%22Macromolecules%22%5BJournal%5D)">Novel Branching Topology in Polyethylenes As Revealed by Light Scattering and 13C NMR.</a> Macromolecules. 33 (19), 6945-6952 (2000).</li>
<li>Wiedemann, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Monofunctional+hyperbranched+ethylene+oligomers%5BTitle%5D)+AND+%22J.+Am.+Chem.+Soc%22%5BJournal%5D)">Monofunctional hyperbranched ethylene oligomers.</a> J. Am. Chem. Soc. 136 (5), 2078-2085 (2014).</li>
<li>Mayo, F. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Chain+Transfer+in+the+Polymerization+of+Styrene%3A+The+Reaction+of+Solvents+with+Free+Radicals1%5BTitle%5D)+AND+%22J.+Am.+Chem.+Soc%22%5BJournal%5D)">Chain Transfer in the Polymerization of Styrene: The Reaction of Solvents with Free Radicals1.</a> J. Am. Chem. Soc. 65 (12), 2324-2329 (1943).</li>
</ol>

The authors declare no competing financial interest.

A methyl-substituted cationic [&#945;-diimine]NiBr2 ethylene polymerization catalyst activated with MAO was examined for its competency for ethylene chain transfer polymerizations. The reactions were monitored via gas uptake measurements to determine the rate and extent of polymerization and catalyst lifetime, and the molecular weight of the resultant polymers were determined via gel permeation chromatography (GPC). Initially, the nickel catalyst was tested over a range of et...

Polyolefins are an important class of industrial polymers with uses in thermoplastics and elastomers. Significant advances in the design of single-site catalysts for the production of polyolefins has led to the ability to tune molecular weight, polydispersity, and polymer microstructure, which leads to a wide range of potential applications.1-3 More recently, chain transfer and chain shuttling polymerizations have been developed to give an additional route to modify the properties of the polymer without having to modify the catalyst.4-6 This system employs a single-site transition metal catalyst and a chain transfer reagent (CTR), which is typically a main group metal alkyl. During this polymerization, the growing polymer chain is able to transfer from the catalyst to the CTR, where the polymer chain remains dormant until it is transferred back to the catalyst. Meanwhile, the alkyl group that was transferred to the catalyst can initiate another polymer chain. In a chain transfer polymerization, one catalyst can initiate a greater number of chains compared to a standard catalytic polymerization. The polymer chains are terminated with the chain transfer metal; therefore further end-group functionalization is possible. This system can be used to change the molecular weight and molecular weight distribution of polyolefins,7 to catalyze Aufbau-like alkyl chain growth on main group metals,8 and for the synthesis of specialty polymers involving multicatalyst systems, such as block copolymers.9,10
Chain transfer polymerizations have been observed most commonly with early transition metals (Hf, Zr) and alkylzinc or alkylaluminum reagents, although examples exist across the transition metal series.5,7,8,11-16 In typical early transition metal catalyst systems, chain transfer is fast, efficient and reversible leading to narrow molecular weight distributions. Chain transfer/shuttling has been observed in mid-to-late transition metals (e.g. Cr, Fe, Co and Ni) with group 2 and 12 metal alkyls, although the rates of transfer are highly variable compared to early metals.4,7,17-19 Two main factors are apparently necessary for efficient chain transfer: a good match of metal-carbon bond dissociation energies for the polymerization catalyst and chain transfer reagent, and an appropriate steric environment to promote bimolecular formation/breakage of alkyl-bridged bimetallic intermediates.20 In the case of late transition metals, if the catalyst does not contain enough steric bulk, beta-hydride (&#946;-H) elimination will be the dominant termination pathway and will generally out-compete chain transfer.
Herein we report on a study of bimetallic chain transfer from nickel to zinc in a bis(2,6-dimethylphenyl)-2,3-butanediimine-based catalyst system with diethylzinc (ZnEt2) through small-scale high-throughput reactions. Chain transfer will be identified by examining changes in the molecular weight (Mw) and dispersity index of the resulting polyethylene through gel-permeation chromatography analysis. Chain transfer will also be identified through 13C NMR analysis of the ratio of vinyl to saturated chain ends as a function of chain transfer agent concentration. An in-depth kinetic analysis of the rates of propagation and chain transfer will also be presented.

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

ethylene polymerizations using parallel pressure reactors and a kinetic analysis of chain transfer polymerization

Ethylene Polymerizations Using Parallel Pressure Reactors and a Kinetic Analysis of Chain Transfer Polymerization

We demonstrate a method for high-throughput catalyst screening using a parallel pressure reactor starting from the initial synthesis of a nickel &#945;-diimine ethylene polymerization catalyst. Initial polymerizations with the catalyst lead to optimized reaction conditions, including catalyst concentration, ethylene pressure and reaction time. Using gas-uptake data for these reactions, a procedure to calculate the initial rate of propagation (kp) is presented. Using the optimized conditions, the ability of the nickel &#945;-diimine polymerization catalyst to undergo chain transfer with diethylzinc (ZnEt2) during ethylene polymerization was investigated. A procedure to assess the ability of the catalyst to undergo chain transfer (from molecular weight and 13C NMR data), calculate the degree of chain transfer, and calculate chain transfer rates (ke) is presented.

The ethylene gas consumption versus time is presented in Figure 1 for the different ethylene pressures tested. This data is used to determine optimized reaction conditions. The ethylene gas consumption versus time is presented in Figure 2A for the catalyst alone samples, which is used to calculate the rate of propagation (kp). Figure 2B shows gel permeation chromatography (GPC) traces for chain transfer polymerizations with 0-1,000 equivalents of diet...

A protocol for the high-throughput analysis of polymerization catalyst, chain transfer polymerizations, polyethylene characterization, and reaction kinetic analysis is presented.

We demonstrate a method for high-throughput catalyst screening using a parallel pressure reactor starting from the initial synthesis of a nickel ...

The overall goal of this procedure is to set up a high throughput polymerization and assess the ability of a catalyst to undergo chain transfer through detailed characterization and kinetic analysis of the resultant polymer. This method helps answer key questions in polymerization catalysis linked into newly designed catalysts, which can exploit chain transfer to produce efficient routes to a variety of polymers. The main advantage of this technique is that high throughput polymerizations allow for efficient catalyst screening and direct comparisons of catalysts over a large range of reaction conditions.Demonstrating this technique will be Dr.Ryan Hugh, a postdoc in my laboratory. First dissolve one milliliter of two three butane Dion and 2.8 milliliters of two six dimethyl annin in 20 milliliters of methanol in a 100 milliliter round bottom flask. After adding 0.4 milliliters of formic acid, stir the reaction at room temperature until the diamine precipitates, which is typically one to two hours.Following this, filter the reaction mixture with a glass frit and filter flask and wash the yellow solid with 20 milliliters of cold methanol. Then dry the solid in vao. In a glove box, combine one gram of dim eth nickel bromide, and 1.1 grams of biz.Two six dimethyl phenyl, two three butane Dion in a 50 milliliter round bottom flask, add 20 milliliters of di chloro methane and stir overnight at room temperature. On the next day, filter the reaction mixture with a glass frit and filter flask. Wash the brown solid with 75 milliliters of chloro methane and dry in vao.Prepare a 0.001 molar catalyst stock solution by adding 0.0041 grams of the previously prepared nickel bromide catalyst into a vial with 7.5 milliliters of toluene to the stir nickel suspension. Add 0.5 milliliters of 30%methyl luane in toluene. Stir for one minute, changing the reaction mixture from a brown suspension to a solution.Next, prepare a 1.2 molar dathyl zinc solution by dissolving 0.25 milliliters of dathyl zinc in 1.75. Milliliters of toluene set up all polymerization reactions in a parallel pressure reactor with overhead stirring housed in a nitrogen atmospheric glove box program. The polymerization in the software indicating the total reaction volume as three milliliters.The purge gas is nitrogen. The reaction gas is ethylene. The pressure as 15 to 150 PSI and the reaction time is one hour.The setup of the reactor, including adding the reagents and solvents, programming the software and securing the overhead storing assembly is the most critical step. Following this insert glass liner reaction vials into the eight wells. Add the reagents according to table one.Use the depth tool to ensure the glass liners are at the appropriate height. Then insert the blade impellers into the overhead assembly. After filling the reaction vials and ensuring the O-rings are properly seated in the metal grooves, carefully place the overhead stirring assembly on the base and screw down in an alternating fashion.Once all screws are sufficiently tightened, press start in the software. Monitor the reaction via gas uptake measurements. After one hour of polymerization, remove the reaction vials from the glove box, precipitate polyethylene with the addition of 5%hydrochloric acid in methanol.Then remove the solvent and dry the polymer under vacuum. After determining the polymer yield dissolves 0.002 grams of the polymer in two milliliters of 1 2 4 tri chloro benzene at 135 degrees Celsius. Use gel permeation chromatography or GPC to analyze the molecular weight and dispersity index of the dried polyethylene.This sample is now ready to be placed on a high temperature GPC for analysis. Next dissolve 0.05 to 0.08 grams of the polymer in 0.5 milliliters of derated tetra chloro eth ethane at 130 degrees Celsius. For high temperature carbon NMR spectroscopy analysis for chain transfer polymerization fill the reactor and program the software following the previously described procedures and analysis.The ethylene gas consumption versus time is presented here for the different ethylene pressures tested. The ethylene gas consumption versus time is shown here for the catalyst alone samples, which is used to calculate the rate of propagation. GPC traces for chain transfer polymerizations with zero to 1000 of ethyl zinc are displayed here.The GPC is used to calculate the molecular weight and dispersity of the polymer samples. The carbon NMR spectra of the polyethylene samples of the full series and a zoomed in spectrum with the peaks labeled are shown here. The molecular weight data is used to calculate the number of chains initiated and the Mayo plot.The fit of the Mayo plot is used to calculate the ratio of the rate of chain transfer to the rate of propagation, which is used to calculate the rate of chain transfer Once mastered, this polymerization can be done in two hours if it is performed properly. While attempting this procedure, it is important to accurately dispense the stock solutions into the reaction vials, ensure the reactor is properly configured and the overhead stirring assembly is properly secured in place. After watching this video, you should have a good understanding of how to set up a high throughput polymerization, characterize the resulting polymer, and assess the ability of a catalyst to undergo chain transfer through kinetic analysis.Don't forget that dathyl, zinc and methyl luminox are pyrophoric and air free. Techniques should always be used when performing this procedure.

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Research

JoVE Journal

Chemistry

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Atom Transfer Radical Polymerization of Functionalized Vinyl Monomers Using Perylene as a Visible Light Photocatalyst

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Crystallization-driven self-assembly (CDSA) displays the unique ability to fabricate cylindrical nanostructures of narrow length distributions. The organocatalyzed ring-opening polymerization of ε-caprolactone and subsequent chain extensions of methyl methacrylate and N,N-dimethyl acrylamide are demonstrated. A living CDSA protocol that produces monodisperse cylinders up to 500 nm in length is outlined.

Synthesis of Monodisperse Cylindrical Nanoparticles via Crystallization-driven Self-assembly of Biodegradable Block Copolymers

Here, we describe protocols for the preparation of trans-cyclobutane fused cyclooctenes (tCBCO), their polymerization to prepare depolymerizable olefinic polymers, and the depolymerization of these polymers under mild conditions. Additionally, protocols for the preparation of depolymerizable networks and compression molding of rigid linear plastics based on this system are described.

Depolymerizable Olefinic Polymers Based on Fused-Ring Cyclooctene Monomers

Time courses for the glycosylase activity of 8-oxoguanine DNA glycosylase are biphasic exhibiting a burst of product formation and a linear steady-state phase. Utilizing quench-flow techniques, the burst and the steady-state rates can be measured, which correspond to excision of 8-oxoguanine and release of the glycosylase from the product DNA, respectively.

Steady-state, Pre-steady-state, and Single-turnover Kinetic Measurement for DNA Glycosylase Activity

This video will illustrate a rapid, efficient method to methacrylate poly(ethylene glycol), enabling chain polymerizations and hydrogel synthesis. It will demonstrate how to similarly introduce methacrylamide functionalities into peptides, detail common analytical methods to assess functionalization efficiency, provide suggestions for troubleshooting and advanced modifications, and demonstrate typical hydrogel characterization techniques.

Microwave-assisted Functionalization of Poly(ethylene glycol) and On-resin Peptides for Use in Chain Polymerizations and Hydrogel Formation

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Tuning a Parallel Segmented Flow Column and Enabling Multiplexed Detection

Learn high-throughput ethylene polymerization methods for catalyst screening and kinetic analysis of chain transfer mechanisms. This protocol enables efficient assessment of polymerization catalysts across diverse reaction conditions.

Ethylene Polymerizations Using Parallel Pressure Reactors and a Kinetic Analysis of Chain Transfer Polymerization

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