The Effect of Hydrogen Bonding on Intramolecular Chain Transfer in Polymerization of Acrylates

Liang, Kun; Hutchinson, Robin A.

doi:10.1002/marc.201100224

Cited by 33 publications

(54 citation statements)

References 51 publications

(122 reference statements)

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“…Firstly, from an experimental point of view, although the reaction was performed under conditions designed to minimize any effect arising from the exothermic nature of the reaction in bulk, local temperature rises are inevitable and can lead to increased rate of both backbiting and β scission relative to propagation. Secondly, as the solution polymerization is conducted in ethanol, hydrogen bonding may result in a decrease in the amount of backbiting relative to the bulk polymerization 41,42 . Finally, the potential of the midchain radical to undergo chain transfer to solvent for the reaction conducted in ethanol, which has not been considered herein, may also lead to a reduction in the products arising from the midchain radical as has been demonstrated to be important for reactions carried out in the presence high concentrations of chain transfer agent 55,56 .…”

Section: Resultsmentioning

confidence: 99%

Determining the effect of side reactions on product distributions in RAFT polymerization by MALDI-TOF MS

et al. 2015

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Reversible Addition-Fragmentation chain Transfer (RAFT) polymerization has emerged as one of the most versatile reversible deactivation radical polymerization techniques and is capable of polymerizing a wide range of monomers under various conditions. One of the most important factors governing the success of a RAFT polymerization is the fraction of living chains at the end of the reaction, which can be maximized by using a low amount of initiator. From the point of view of the process, it is tempting to perform the polymerization in solution, which allows a better mixing. However, in this work it is shown that this choice may be negative for the quality of the polymer. Detailed analysis using Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS) of poly(nbutyl acrylate) (pBA) obtained at high conversion in the RAFT solution polymerization revealed that in addition to the polymer chains, formed by the RAFT mechanism, there were two distinct populations resulting from chain transfer to solvent and transfer to polymer followed by β-scission. Complementary results from Size Exclusion Chromatography coupled with Multi Angle Light Scattering detector (SEC/MALS), quantum chemical calculations, and a mathematical model that predicts product distributions, were also used to further confirm the assigned structures. The results highlight the scope and limitation on the living fraction of chains due to chain transfer events using RAFT polymerization and reversible deactivation radical polymerizations in general, and furthermore, yielded information about the fate of midchain radicals formed by intramolecular transfer to polymer.

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Section: Resultsmentioning

confidence: 99%

Determining the effect of side reactions on product distributions in RAFT polymerization by MALDI-TOF MS

et al. 2015

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“…In the previous study,22 it was found that the PLP–SEC technique could be applied to determine k p values for the homopolymerization of HEA with a pulse repetition rate of 100 Hz under conditions at which other acrylates cannot be studied. It was concluded that intermolecular hydrogen bonding between HEA monomers significantly suppresses backbiting, a reaction that is the main cause of the loss of PLP structure in the resulting MMD.…”

Section: Resultsmentioning

confidence: 99%

“…HEA (96% purity, containing 200–650 ppm monomethyl ether hydroquinone as inhibitor), ST (99% purity, containing 10–15 ppm of 4‐tert‐butylcatechol), photoinitiator 2,2‐dimethoxy‐2‐phenylacetophenone (DMPA, 99% purity), and anhydrous dimethyl sulfoxide‐d6 (DMSO‐d6, containing 99.9% D) were all obtained from Sigma–Aldrich and used as received. Low‐ conversion polymerizations were conducted in a pulsed laser setup as described in the previous articles 20–22. Monomer mixtures in bulk with 5 mmol L −1 DMPA photoinitiator were added to a quartz cell and exposed to laser energy using a Spectra‐Physics Quanta‐Ray 100 Hz Nd:YAG producing a 355 nm laser pulse of duration 7–10 ns and energy of 1–10 mJ per pulse, with the output repetition rate controlled by a digital delay generator (DDG, Stanford Instruments).…”

Section: Methodsmentioning

confidence: 99%

“…In this work, we apply the PLP–SEC technique to the study of bulk copolymerization of ST/HEA. As well as reporting the first values of k p,cop for this system, we have finalized SEC calibration for pHEA, allowing us to update our preliminary estimates for the chain‐end propagation kinetics for bulk HEA 22. In addition, all of the kinetic rate coefficients for the PUE model shown in Scheme have been determined computationally using DFT at the 6‐31G (d,p) level of theory, with the resulting estimates for k p,cop compared with experiment.…”

Section: Introductionmentioning

confidence: 99%

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A Combined Computational and Experimental Study on the Free‐Radical Copolymerization of Styrene and Hydroxyethyl Acrylate

Mavroudakis

Liang

Moscatelli

et al. 2012

Macro Chemistry & Physics

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Bulk free‐radical copolymerization of styrene and 2‐hydroxyethyl acrylate (HEA) is investigated experimentally at 50 °C using pulsed‐laser polymerization and computationally using ab initio simulations. Arrhenius parameters for HEA chain‐end homopropagation are A = 1.72 × 107 L mol−1 s−1 and Ea = 16.8 kJ mol−1, based on experiments between 20 and 60 °C. Copolymer composition data are well fitted by the terminal model with reactivity ratios rST = 0.44 ± 0.03 and rHEA = 0.18 ± 0.04, but the variation in the propagation rate coefficient with monomer composition is underpredicted. Results are compared with computational predictions assuming the terminal as well as the penultimate unit effect (PUE) model. Intramolecular H‐bonding is shown to have a significant influence on PUE calculations. Discrepancies between computational predictions and experiment are attributed to the influence of intermolecular H‐bonding.

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“…The propagation rate coefficients of hydrophilic monomers in hydrophobic solvents are often larger than those in hydrophilic solvents. 12,13 This makes SqRAFTwP more attractive and powerful because the amount of hydrophilic monomers can be reduced to a negligible level, i.e., the adsorbing layer will not be so thick.…”

mentioning

confidence: 99%

Efficient Production of Block-copolymer-coated Ceramic Nanoparticles by Sequential Reversible Addition–Fragmentation Chain-transfer Polymerizations with Particles (SqRAFTwP)

Arita

2013

Chemistry Letters

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Ceramic nanoparticles (NPs) were surface modified and dispersed by in situ synthesized block copolymers. Living radical polymerization with sequential addition of monomers enables the effective coating of ceramic NPs by block copolymers. The method enables us to add stable polymer layers on any kind of NPs; therefore, it can help the mass production of polymer-coated inorganic NPs and drastically reduce the cost, without sacrificing their performance.Composite materials, especially composites of inorganic materials and polymers, are very attractive because they can exhibit promising new properties that have been believed to be trade-off functions.1 In order to solve the trade-off, stable dispersions of filler nanoparticles (NPs) in a polymer matrix has to be achieved. Polymer grafting to the surface of inorganic materials is promising. 26 Because polymeric materials are in a metastable state in most cases, composite materials of just blended polymers and inorganic materials are not stable, i.e., they will segregate from each other. When the inorganic NPs have grafted polymer chains, segregation will be inhibited because the same polymer material can be miscible.Many studies of grafting polymer chains on NPs have been reported. Some of the studies proved the advantage of polymer grafting on dispersions of inorganic NPs in polymer matrixes. Polymer grafting is effective, but all of the polymer grafting methods need anchoring reagents to connect inorganic surfaces and polymers. 37 Recently, I proposed a method for the direct production of polymer-grafted ceramic NPs without using anchor and/or linker reagents.2 This technique drastically increases the combinations of ceramics and polymers that can be grafted and reduces the number of steps needed to prepare polymer-grafted ceramic NPs; however, the method was not sufficient for mass production of polymer-grafted ceramic NPs. For industrial applications of high-performance polymer-grafted NPs, mass production without sacrificing their performances must be achieved.In order to solve this problem, a new method of preparing polymer-coated ceramic NPs has been developed. The method proposed here needs no reagent to connect inorganic surfaces and polymers, reduces the number of chemical processes, and enables densely polymer-coated ceramic NPs to be produced on a very large scale (more than 10 g of ceramic NPs can be coated at once in a 300-mL flask; see Figure S1 in the Supporting Information). 8The polymer-coated NPs produced have similar structures to polymer-grafted NPs and block-copolymer-micelle-protected NPs, so their properties and performances are similar. 9The method is facile, as shown in Scheme 1. As a representative example, coating of several ceramic NPs (silica, ¡-Al 2 O 3 , £-Fe 2 O 3 , BaTiO 3 , and TiN) by poly(2-hydroxyethyl acrylate)-b-polystyrene (PHEA-b-PS) was performed as follows: Ceramic NPs (1 g) were weighed, loaded in a 20-mL test tube with a screw cap, and transferred to an oxygen-and moisture-free glove box. Then, 2 mL of hydrophobic solve...

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The Effect of Hydrogen Bonding on Intramolecular Chain Transfer in Polymerization of Acrylates

Cited by 33 publications

References 51 publications

Determining the effect of side reactions on product distributions in RAFT polymerization by MALDI-TOF MS

Determining the effect of side reactions on product distributions in RAFT polymerization by MALDI-TOF MS

A Combined Computational and Experimental Study on the Free‐Radical Copolymerization of Styrene and Hydroxyethyl Acrylate

Efficient Production of Block-copolymer-coated Ceramic Nanoparticles by Sequential Reversible Addition–Fragmentation Chain-transfer Polymerizations with Particles (SqRAFTwP)

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