Synthesis of Ultrahigh Molecular Weight Polymers Containing Reactive Functionality with Low PDIs by Polymerizations of Long-Chain α-Olefins in the Presence of Their Nonconjugated Dienes by Cp*TiMe2(O-2,6-iPr2C6H3)–Borate Catalyst

Abstract

Copolymerizations of 1-decene (DC) with 1,9-decadiene (DCD), 1-dodecene (DD) with 1,11-dodecadiene (DDD), and 1-tetradecene (TD) with 1,13-tetradecadiene (TDD), using Cp*TiMe2(O-2,6-iPr2C6H3) (1)–[Ph3C][B(C6F5)4] (borate) catalyst in the presence of AliBu3/Al(n-C8H17)3 proceeded in a quasi-living manner in n-hexane at −30 to −50 °C, affording ultrahigh molecular weight (UHMW) copolymers containing terminal olefinic double bonds in the side chain with rather low PDI (Mw/Mn) values. In the DC/DCD copolymerization, the resultant copolymer prepared at −40 °C possessed UHMW (Mn = 1.40 × 106 after 45 min) with low PDI (Mw/Mn = 1.39); both the activity and the PDI value decreased at low polymerization temperature (Mn = 5.38 × 105, Mw/Mn = 1.18, after 120 min at −50 °C). UHMW poly(TD-co-TDD) was also obtained in the copolymerization at −30 °C (Mn = 9.12 × 105, Mw/Mn = 1.51, after 120 min), using this catalyst.

Analysis of Ethylene Copolymers with Long-Chain α-Olefins (1-Dodecene, 1-Tetradecene, 1-Hexadecene): A Transition between Main Chain Crystallization and Side Chain Crystallization

“…Ethylene (E) copolymers with 1-dodecene (DD), 1-tetradecene (TD), and 1-hexadecene (HD) were prepared by copolymerization in toluene using Cp*TiCl 2 (O-2,6- i Pr 2 -4-SiEt 3 C 6 H 2 ) (Cp* = C 5 Me 5 ) catalyst in the presence of methylaluminoxane (MAO) cocatalyst. The titanium catalyst has been chosen in this study because the catalyst exhibited notable catalytic activities for E/DD copolymerization with efficient DD incorporation to afford the copolymers. , The catalysts of this type are known to be effective for the synthesis of new ethylene copolymers − with sterically encumbered olefins (disubstituted olefins, branched α-olefins), cyclic olefins, and aromatic vinyl monomers, as well as the synthesis of poly­(LCAO)­s. ,, These copolymerizations were conducted with the termination of low comonomer conversions (less than 10%, short period) to obtain the copolymer with uniform compositions (to avoid changes in the LCAO concentrations during the polymerization runs). The results are summarized in Table .…”

“…The Cp*TiCl 2 (O-2,6- i Pr 2 -4-SiEt 3 -C 6 H 2 )–MAO catalyst system enabled the synthesis of the copolymers with unimodal molecular weight distributions (Table ) and with uniform compositions (confirmed by DSC thermograms). In addition to the melting temperatures ( T m values) corresponding to the so-called main chain crystallization (samples with low LCAO contents) and side chain crystallization [as observed in poly­(DD), poly­(TD), and poly­(HD), polymer samples with high LCAO contents], − the other T m values were observed, especially in poly­(E- co -HD)­s; the wide-angle X-ray diffraction (WAXD) data clearly suggest the presence of another crystalline phase. These T m values in poly­(E- co -TD)­s and poly­(E- co -DD)­s with rather high TD or DD contents were affected by the heating conditions in the measurement of DSC thermograms (5, 10 °C/min, Table , the additional thermograms are shown in the SI), suggesting that the driving force for generating crystal packing (observed T m ) should be weak and affected by the length of the alkyl side chains.…”

“… 23 , 24 In contrast, poly(α-olefin)s, especially those consisting of long-chain α-olefins [LCAOs, 1-dodecene (DD), 1-tetradecene (TD), 1-hexadecene (HD), 1-octadecene, etc. ], 25 − 29 are semicrystalline branched (highly entangled) macromolecules with a high graft density, and the polymers are thus recognized as the simplest bottlebrush polymers. The melting temperatures in poly(LCAO)s are affected by the branch length and the stereoregularity ( Table 1 ).…”

“…Ultrahigh-molecular-weight polymers, possessing highly entangled bottlebrush architectures, are used as drag reducing agents for improved transport (piping capacity) of crude oil and petroleum products in pipeline methods. , In contrast, poly­(α-olefin)­s, especially those consisting of long-chain α-olefins [LCAOs, 1-dodecene (DD), 1-tetradecene (TD), 1-hexadecene (HD), 1-octadecene, etc. ], − are semicrystalline branched (highly entangled) macromolecules with a high graft density, and the polymers are thus recognized as the simplest bottlebrush polymers. The melting temperatures in poly­(LCAO)­s are affected by the branch length and the stereoregularity (Table ).…”

Preparation of High-Purity Ammonium Tetrakis(pentafluorophenyl)borate for the Activation of Olefin Polymerization Catalysts

“…Another type of co-catalyst, [PhN(Me) 2 -H] + [B(C 6 F 5 ) 4 ] − or [Ph 3 C] + [B(C 6 F 5 ) 4 ] − , was developed for the activation of organometallic complexes, which is used in a solution process in which the catalyst retention time is relatively short (<20 min) [13][14][15]. Replacement of excess MAO with stoichiometric amounts of [B(C 6 F 5 ) 4 ] − -based co-catalyst has also been a crucial issue in the development of Cr-based ethylene tetramerization catalysts [16][17][18] ] − are insoluble in aliphatic hydrocarbon solvents (e.g., hexane, cyclohexane, or methylcyclohexane), in which the commercial solution process of olefin polymerization is performed.…”