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Topical Collection "Polymerization and Kinetic Studies"

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A topical collection in Polymers (ISSN 2073-4360). This collection belongs to the section "Polymer Chemistry".

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Prof. Dr. Shin-Ichi Yusa

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Department of Materials Science and Chemistry, University of Hyogo, Shosha, Himeji 2167, Hyogo, Japan
Interests: controlled/living radical polymerization; RAFT; TERP; water-soluble polymer; self-organization; polymer micelle; bioconjugate polymer
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Prof. Dr. Binyuan Liu

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Hebei Key Laboratory of Functional Polymers, Department of Polymer Materials and Engineering, Hebei University of Technology, 8 Guangrong Street, Tianjin 300130, China
Interests: ecological environment (carbon dioxide, biomass, etc.) polymer synthesis and utilization; olefin coordination polymerization and new catalysts; new method for structure-controlled polymerization
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Topical Collection Information

Dear Colleagues,

In polymer chemistry, the study of polymerization kinetics is fundamental to the production of polymers. Polymerization is an important process of combining molecules to form polymer chains or even complex topological chains, in which bifunction or multifunction monomers react to form dimers, trimers, longer oligomers, and eventually long chain polymers. Most recently, the concept of precision polymer synthesis has emerged, which seeks to control all aspects of polymer structure and needs basic and advanced knowledge about the kinetics and reaction mechanism of their formation, i.e., mechanism of polymerization in different media, effect of reaction conditions, effect of modifying additives, etc.

This Topic Collection of Polymers on “Polymerization and Kinetic Studies” will be especially focused on the application of kinetic studies to precision polymerization and the use of insights derived from polymerization kinetics to the synthesis of new polymers and copolymers.

Prof. Dr. Shin-Ichi Yusa
Prof. Dr. Binyuan Liu
Collection Editors

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Keywords

precision polymerization
reversible deactivation radical polymerization
living/controlled polymerization
step polymerization
copolymerization
branching

Published Papers (8 papers)

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2023

Jump to: 2022

Open AccessArticle

Synthesis of Ultrahigh Molecular Weight Poly(methyl Methacrylate) via the Polymerization of MMA Initiated by the Combination of Palladium Carboxylates with Thiols

and

Polymers 2023, 15(11), 2501; https://doi.org/10.3390/polym15112501 - 29 May 2023

Viewed by 694

Abstract

A novel synthesis of ultrahigh molecular weight poly(methyl methacrylate) (PMMA) using organosulfur compounds combined with a catalytical amount of transition metal carboxylates as an initiator has been developed. The combination of 1-octanethiol with palladium trifluoroacetate (Pd(CF₃COO)₂) was found to be a very efficient initiator for the polymerization of methyl methacrylate (MMA). An ultrahigh molecular weight PMMA with a number-average molecular weight of 1.68 × 10⁶ Da and a weight-average molecular weight of 5.38 × 10⁶ Da has been synthesized at the optimal formulation of [MMA]:[Pd(CF₃COO)₂]:[1-octanethiol] = 94,300:8:23 at 70 °C. A kinetic study showed that the reaction orders with respect to Pd(CF₃COO)₂, 1-octanethiol, and MMA are 0.64, 1.26, and 1.46, respectively. A variety of techniques such as proton nuclear magnetic resonance spectroscopy (¹H NMR), electrospray ionization mass spectroscopy (ESI-MS), size exclusion chromatography (SEC), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and electron paramagnetic resonance spectroscopy (EPR) were employed to characterize the produced PMMA and palladium nanoparticles (Pd NPs). The results revealed that Pd(CF₃COO)₂ was firstly reduced by the excess of 1-octanethiol to form Pd NPs at the early stage of the polymerization, followed by the adsorption of 1-octanethiol on the surface of nanoparticles and subsequent generation of corresponding thiyl radicals to initiate the polymerization of MMA. Full article

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Open AccessArticle

Phosphazene Functionalized Silsesquioxane-Based Porous Polymer as Thermally Stable and Reusable Catalyst for Bulk Ring-Opening Polymerization of ε-Caprolactone

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Polymers 2023, 15(5), 1291; https://doi.org/10.3390/polym15051291 - 03 Mar 2023

Viewed by 998

Abstract

The bulk ring-opening polymerization (ROP) of ε-caprolactone using phosphazene-containing porous polymeric material (HPCP) has been studied at high reaction temperatures (130–150 °C). HPCP in conjunction with benzyl alcohol as an initiator induced the living ROP of ε-caprolactone, affording polyesters with a controlled molecular weight up to 6000 g mol⁻¹ and moderate polydispersity (Ð~1.5) under optimized conditions ([BnOH]/[CL] = 50; HPCP: 0.63 mM; 150 °C). Poly(ε-caprolactone)s with higher molecular weight (up to M_n = 14,000 g mol⁻¹, Ð~1.9) were obtained at a lower temperature, at 130 °C. Due to its high thermal and chemical stability, HPCP can be reused for at least three consecutive cycles without a significant decrease in the catalyst efficiency. The tentative mechanism of the HPCP-catalyzed ROP of ε-caprolactone, the key stage of which consists of the activation of the initiator through the basic sites of the catalyst, was proposed. Full article

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Open AccessArticle

DFT and ONIOM Simulation of 1,3-Butadiene Polymerization Catalyzed by Neodymium-Based Ziegler–Natta System

Alexey N. Masliy

Ildar G. Akhmetov

Andrey M. Kuznetsov

and

Ilsiya M. Davletbaeva

Polymers 2023, 15(5), 1166; https://doi.org/10.3390/polym15051166 - 25 Feb 2023

Viewed by 956

Abstract

Using modern methods of quantum chemistry, a theoretical substantiation of the high cis-stereospecificity of 1,3-butadiene polymerization catalyzed by the neodymium-based Ziegler–Natta system was carried out. For DFT and ONIOM simulation, the most cis-stereospecific active site of the catalytic system was used. By analyzing the total energy, as well as the enthalpy and Gibbs free energy of the simulated catalytically active centers, it was found that the coordination of 1,3-butadiene in the trans-form was more favorable than in the cis-form by 11 kJ/mol. However, as a result of π-allylic insertion mechanism modeling, it was found that the activation energy of cis-1,3-butadiene insertion into the π-allylic neodymium–carbon bond of the terminal group on the reactive growing chain was 10–15 kJ/mol lower than the activation energy of trans-1,3-butadiene insertion. The activation energies did not change when both trans-1,4-butadiene and cis-1,4-butadiene were used for modeling. That is, 1,4-cis-regulation was due not to the primary coordination of 1,3-butadiene in its cis-configuration, but to its lower energy of attachment to the active site. The obtained results allowed us to clarify the mechanism of the high cis-stereospecificity of 1,3-butadiene polymerization by the neodymium-based Ziegler–Natta system. Full article

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2022

Jump to: 2023

Open AccessArticle

Polymerization of Hexene-1 and Propylene over Supported Titanium–Magnesium Catalyst: Comparative Data on the Polymerization Kinetics and Molecular Weight Characteristics of Polymers

Mikhail Matsko

Ludmila Echevskaya

and

Vladimir Zakharov

Polymers 2023, 15(1), 87; https://doi.org/10.3390/polym15010087 - 26 Dec 2022

Viewed by 1225

Abstract

Data are presented on the great differences of the kinetics of hexene-1 and propylene polymerization over the same supported titanium–magnesium catalyst, as well as molecular weight and molecular weight distribution of the polymers produced. It is found that the composition of cocatalysts (AlEt₃ or Al(i-Bu)₃ greatly affects the kinetics of hexene-1 polymerization and molecular weight distribution of polyhexene, contrary to data obtained at propylene polymerization. The presence of hydrogen at hexene-1 polymerization leads to a much higher increase of activity in comparison with propylene polymerization. Possible reasons for these differences are discussed on the basis of experimental results. Full article

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Open AccessArticle

Temperature Dependence of the Kinetic Parameters of the Titanium–Magnesium Catalyzed Propylene Polymerization

and

Polymers 2022, 14(23), 5183; https://doi.org/10.3390/polym14235183 - 28 Nov 2022

Viewed by 757

Abstract

This paper provides a study of the liquid-phase polypropylene polymerization on a heterogeneous titanium–magnesium Ziegler–Natta-type catalyst. A kinetic model was developed that included the activation of potential active centers, chain growth, transferring the chains to hydrogen and monomer, and the deactivation of active centers. The model was created to predict the polymerization rate, polymer yield, and average molecular weights of polymer chains where the polymerization temperature changes from 40 to 90 °C. In developing polycentric kinetic models, there is a difficulty associated with evaluating the kinetic constants of the rates of elementary reactions/stages in polymerization. Each heterogeneous titanium–magnesium catalyst (TMC), including a co-catalyst, as well as an internal and an external electron donor, has its own set of kinetic parameters. Therefore, its kinetic parameters must be defined for each new catalyst. The presented algorithm for identifying the kinetic constants of rates starts with a kinetic model that considers one type of active centers. At the second stage, a deconvolutional analysis is used for the molecular weight distribution (MWD) of the gel permeation chromatography (GPC) data of the polypropylene samples and the most probable distribution of Flory chain lengths is found for each type of active centers. At the third stage, the single-center model is transformed into a polycentric kinetic model. For the catalyst system, five types of active centers were identified, together with a mass fraction and a number-average molecular weight for each active center type of the catalyst, which is consistent with the published results for similar Ti-based Ziegler–Natta catalysts. Full article

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Open AccessArticle

Slurry Homopolymerization of Ethylene Using Thermostable α-Diimine Nickel Catalysts Covalently Linked to Silica Supports via Substituents on Acenaphthequinone-Backbone

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Polymers 2022, 14(17), 3684; https://doi.org/10.3390/polym14173684 - 05 Sep 2022

Cited by 2 | Viewed by 1089

Abstract

Four supported α-diimine nickel(II) catalysts covalently linked to silica via hydroxyl functionality on α-diimine acenaphthequinone-backbone were prepared and used in slurry polymerizations of ethylene to produce branched polyethylenes. The catalytic activities of these still reached 10⁶ g/molNi·h at 70 °C. The life of the supported catalyst is prolonged, as can be seen from the kinetic profile. The molecular weight of the polyethylene obtained by the 955 silica gel supported catalyst was higher than that obtained by the 2408D silica gel supported catalyst. The melting points of polyethylene obtained by the supported catalysts S-C1-a/b are all above 110 °C. Compared with the homogeneous catalyst, the branching numbers of the polyethylenes obtained by the supported catalysts S-C1-a/b is significantly lower. The polyethylenes obtained by supported catalyst S-C1-a/b at 30–50 °C are free-flowing particles, which is obviously better than the rubber-like cluster polymer obtained from homogeneous catalyst. Full article

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Open AccessArticle

Progress toward Polymerization Reaction Monitoring with Different Dienes: How Small Amounts of Dienes Affect ansa-Zirconocenes/Borate/Triisobutylaluminium Catalyst Systems

Amjad Ali

Jamile Mohammadi Moradian

and

Polymers 2022, 14(16), 3239; https://doi.org/10.3390/polym14163239 - 09 Aug 2022

Cited by 2 | Viewed by 1028

Abstract

The objectives of this work were to address the fundamental characteristics of ansa-zirconocene catalyzed E/diene copolymerization and E/diene/1-hexene and E/diene/propylene terpolymerizations, and the quantitative relationship between diene structure and polymer chain propagation rate constant in term of quantifiable catalytic active sites. One of the most important but unknown factors in olefins ansa-zirconocene complexes is the distribution of the catalyst between sites actively participating in polymer chain formation and dormant sites. A set of ethylene/dienes copolymerizations, and ethylene/dienes/1-hexene and ethylene/dienes/1-hexene terpolymerizations catalyzed with ansa-zirconocenes/borate/triisobutylaluminium (rac-Et(Ind)₂ZrCl₂/[Ph₃C][B(C₆F₅)₄]/triisobutylaluminium (TIBA) were performed in toluene at 50 °C To determine the active center [C*]/[Zr] ratio variation in the copolymerization of E with different dienes and their terpolymerization with 1-hexene and propylene, each polymer propagation chain ends were quenched with 2-thiophenecarbonyl, which selectively quenches the metal–polymer bonds through acyl chloride. The ethylene, propylene, 1-hexene, and diene composition-based propagation rate constants (k_pE, k_pP, k_p1-H, and k_pdiene), thermal (melting and crystalline) properties, composition (mol% of ethylene, propylene, 1-hexene, and diene), molecular weight, and polydispersity were also studied in this work. Systematic comparisons of the proportion of catalytically [Zr]/[C*] active sites and polymerization rate constant (k_p) for ansa-zirconocenes catalyzed E/diene, E/diene/1-hexene, and E/diene/propylene polymerization have not been reported before. We evaluated the addition of 1-hexene and propylene as termonomers in the copolymerization with E/diene. To make a comparison for each diene under identical conditions, we started the polymerization by introducing an 80/20 mole ratio of E/P and 0.12 mol/L of 1-hexene in the system. The catalyst behavior against different dienes, 1-hexene, and propylene is very interesting, including changes in thermal properties, cyclization of 1-hexene, and decreased incorporation of isoprene and butadiene, changes in the diffusion barriers in the system, and its effect on k_p. Full article

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Open AccessArticle

Synthesis of a Curing Agent Derived from Limonene and the Study of Its Performance to Polymerize a Biobased Epoxy Resin Using the Epoxy/Thiol-Ene Photopolymerization Technique

Ricardo Acosta Ortiz

Rebeca Sadai Sánchez Huerta

Antonio Serguei Ledezma Pérez

and

Aida E. García Valdez

Polymers 2022, 14(11), 2192; https://doi.org/10.3390/polym14112192 - 28 May 2022

Cited by 3 | Viewed by 1715

Abstract

This study describes the synthesis of a curing agent derived from limonene as well as its application to prepare biobased thermoset polymers via the epoxy/thiol-ene photopolymerization (ETE) method. A biobased commercial epoxy resin was used to synthesize a crosslinked polymeric matrix of polyether-polythioether type. The preparation of the curing agent required two steps. First, a diamine intermediate was prepared by means of a thiol-ene coupling reaction between limonene and cysteamine hydrochloride. Second, the primary amino groups of the intermediate compound were alkylated using allyl bromide. The obtained ditertiary amine-functionalized limonene compound was purified and characterized by FTIR and NMR spectroscopies along with GC-MS. The curing agent was formulated with a tetrafunctional thiol in stoichiometric ratio, and a photoinitiator at 1 mol % concentration, as the components of a thiol-ene system (TES). Two formulations were prepared in which molar concentrations of 30 and 40 mol % of the TES were added to the epoxy resin. The kinetics of the ETE photopolymerizations were determined by means of Real-Time FTIR spectroscopy, which demonstrated high reactivity by observing photopolymerization rates in the range of 1.50–2.25 s⁻¹ for the epoxy, double bonds and thiol groups. The obtained polymers were analyzed by thermal and thermo-mechanical techniques finding glass transition temperatures (Tg) of 60 °C and 52 °C for the polymers derived from the formulations with 30 mol % and 40 mol % of TES, respectively. Potential applications for these materials can be foreseen in the area of coatings. Full article

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Topical Collection "Polymerization and Kinetic Studies"

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2023

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2022

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