Polymerization of cyclic monomers, 3. Synthesis, radical and cationic polymerization of bicyclic 2‐methylene‐1,3‐dioxepanes

Moszner, Norbert; Völkel, Thomas; Rheinberger, Volker; Klemm, Elisabeth

doi:10.1002/macp.1997.021980307

Cited by 21 publications

(13 citation statements)

References 10 publications

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“…The NMR spectra still give raise to the assumption that a certain amount of non-opened units must be present, but most of the 7-membered rings will undergo ring-opening leaving the attached 5-membered cycle unchanged. This is also consistent with the statements in [130] where a variety of 4-methylene-3.5.8.10-tetraoxabicyclo[5.3.0]undecanes have been investigated. It strongly refers to our own findings, that ketene acetals can not be polymerized in solution, but preferably in bulk.…”

Section: -Methylene-13-dioxepanessupporting

confidence: 91%

“…It strongly refers to our own findings, that ketene acetals can not be polymerized in solution, but preferably in bulk. The photoradical polymerization in [130] yields polyesters with molecular weights up to 12 000 g/ mol, but no direct relation to the substituents in 9-position.…”

Section: -Methylene-13-dioxepanesmentioning

confidence: 99%

“…One approach was the introduction of bulky substituents in 4.5-position in form of second cycles [41,128,129]. After some synthetic problems have been overcome by Moszner et al a wide variety of e. g. 4-methylene-3.5.8.10-tetraoxabicyclo-[5.3.0]undecanes is available today [130]. Their general polymerization procedure involves a high extent of ringopening following the mechanism in Eq.…”

Section: -Methylene-13-dioxepanesmentioning

confidence: 99%

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Ring-opening polymerization of heterocycles bearing substituted and unsubstituted exo-methylene groups - a review

Klemm

Schulze

1999

Acta Polym.

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Monocyclic monomers bearing exo‐methylene groups are likely to undergo ring‐opening polymerization under the conditions of radical or cationic initiation. Several structural features will determine the course of reaction after initiation by species that exclusively attack the exo‐methylene functionality. Reviewing some of the most common classes of monocyclic heterocycles it becomes obvious that a monomer has to meet certain structural preconditions that makes them suitable for isomerizations. Among the considered heterocycles there are some types of monomers possessing an outstanding ring‐opening behavior following polymerization mechanisms free from side‐reactions. The combination of strain release due to ring‐opening isomerization, an energy decrease in the transition state caused by the formation of carbonyl‐functionalities and an appropriate stabilization of the growing chain end by steric and electronic effects may lead to clear ring‐opening mechanisms. However, this property remains restricted to only some special monomers with simple aromatic substituents being attached to the cycle. Hence a variety of cyclic ketene acetals, enolethers, (meth)acrylates, carbonates, lactones and lactames have been chosen in order to demonstrate both the possibilities and limits of ring‐opening.

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Section: -Methylene-13-dioxepanessupporting

confidence: 91%

Section: -Methylene-13-dioxepanesmentioning

confidence: 99%

Section: -Methylene-13-dioxepanesmentioning

confidence: 99%

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Ring-opening polymerization of heterocycles bearing substituted and unsubstituted exo-methylene groups - a review

Klemm

Schulze

1999

Acta Polym.

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“…Over the last 20 years, free radical ring-opening polymerization has been seen as a solution to the problem of polymerization volume shrinkage. Reports, [1][2][3][4][5][6][7][8][9][10][11][12][13][14] patents, [15][16][17][18] and reviews 19,20,21 in this field appear regularly in the literature, and a monograph 22 also has been published. Whereas much work continues on ketene acetal 23 and vinylcyclopropane derivatives, 24 we have developed novel cyclic allylic sulfide monomers such as the activated monomer 1 5,15,25 and the unactivated monomers 2-4.…”

Section: Introductionmentioning

confidence: 99%

Free radical ring-opening polymerization of cyclic allylic sulfides: Liquid monomers with low polymerization volume shrinkage

Evans

Rizzardo

2000

J. Polym. Sci. A Polym. Chem.

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The free radical polymerization of four methylated cyclic allylic sulfides was examined with reference to their polymerization volume shrinkage and the effect of ring size on reactivity. The compounds examined were 2‐methyl‐5‐methylene‐1,3‐dithiane (5) (solid), 2‐methyl‐6‐methylene‐1,4‐dithiepane (6) (liquid), 6‐methyl‐3‐methylene‐1,5‐dithiacyclooctane (7) (liquid), and 6,8‐dimethyl‐3‐methylene‐1,5‐dithiacyclooctane (8) (liquid). The monomers were stable materials not requiring any special handling or storage conditions. They were polymerized in bulk using thermal azobisisobutyronitrile (AIBN, VAZO88) and photochemical initiators (Ciba DAROCUR 1173) and in benzene solutions (AIBN, 70 °C). The six‐membered ring monomer 5 was unreactive whereas seven‐membered ring monomer 6 polymerized to high conversion in bulk. In addition, 6 did not polymerize in benzene solution at 70 °C at [6] = 1.25M. Eight‐membered ring monomers 7 and 8 polymerized in bulk to complete conversion with thermal and photochemical initiators to give lightly crosslinked materials. Near complete conversion to soluble polymers could be obtained in solution polymerizations in benzene. Soluble polymers were also obtained in photochemical initiated bulk polymerizations by lowering initiator concentrations or length of irradiation. The methyl substituent had no effect on which allylic carbon–sulfur bond fragmented in the ring‐opening step. The polymerization volume shrinkages of monomers 7 and 8 were 1.5 and 2.4% respectively and together with monomer 4 (1.5–2.0% shrinkage) are the best available liquid free radical ring‐opening monomers that can be polymerized in bulk at room temperature. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 202–215, 2001

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“…In this context, we showed [5] that bicyclic 2-methylene-1,3-dioxepanes primarily undergo a radical ring-opening polymerization, while their cationic photopolymerization is mainly a vinyl polymerization. Previously, we reported about the synthesis and polymerization of unsaturated spiro orthocarbonates [6] and vinylcyclopropanes [ 1,7].…”

mentioning

confidence: 99%

Polymerization of Cyclic Monomers. 5. Synthesis and radical polymerization of 4-methylene-3,5-dioxabicyclo[5.1.0]octane

1998

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Cyclic monomers, such as spiro orthocarbonates or spiro orthoesters, can show a near zero volume shrinkage or sometimes expansion in volume during their ring-opening polymerization. Therefore, they are of interest in the fields of precision casting, dental fillings, or adhesives [2]. 2-Methylene-1,3-dioxepane derivatives are known as monomers which polymerize radically with almost quantitative ring-opening in the presence of di-tert-butyl peroxide (DTBP) at 120 "C and with radical photoinitiators at room temperature [3-51, respectively. In this context, we showed [5] that bicyclic 2-methylene-1,3-dioxepanes primarily undergo a radical ring-opening polymerization, while their cationic photopolymerization is mainly a vinyl polymerization. Previously, we reported about the synthesis and polymerization of unsaturated spiro orthocarbonates [6] and vinylcyclopropanes [ 1,7].The ring-opening behaviour of cyclic monomers can be influenced by fusing them with a strained ring. Therefore, the present paper describes the synthesis of 4-methylene-3,5dioxabicyclo[5.1 .O]octane (2) and the radical and cationic polymerization of 2 and of 2-methylene-1,3-dioxepane (MDE) as a model compound.The monomer 2 was prepared by dehydrobromination of bromomethyl dioxepane 1 with potassium tert-butoxide with 63% yield. Compound 1 can be obtained by acetalization of (2)-1,2-bis(hydroxymethyl)cyclopropane with bromoacetaldehyde diethyl acetal in the presence of p-toluenesulfonic acid (PTSA) with 77% yield. The synthesized bicyclic monomer2 is a colourless liquid compound which is only stable under exclusion of moisture or acid compounds.The characterization of the new bicyclic monomer 2 was carried out by 'H NMR, I3C NMR, IR spectroscopy and elemental analyses. The formation of the cyclopropane ring is supported by the presence of the peaks assignable to CH2 or CH of the cyclopropane ring at 6= 0.67-1.47 ppm in the lH NMR spectrum. The chemical shift of the singulett of the methylene protons is at 3.51 ppm, whereas the signal arising from the carbon atom 4 is at about 6 = 165.27 ppm.The radical polymerization of 2 and MDE was carried out in the presence of DtBPO at 120 "C. In case of MDE, highly viscous polymerizates with number-average molecular weights of 7700 or 9150 g/mol were obtained. Contrary to this, the radical bulk polymerization of 2 yielded crosslinked polymers (Tab. 1). Tab. 1 Bulk polymerization of 4-Methylen-3S-dioxabicyclo[5.l.0]octane (2) and MDE in the presence of DtB-PO at 120 "C, polymerization time 16 h Monomer [DtBPO] Conversion Mn (mol-%) (%) (dmol) MDE 2.5 83.9 7700 MDE 1 .0 76.2 9150 2 2.5 54.0 insoluble product 2 1 .0 42.3 insoluble productThe spectroscopic characterization of the obtained polymers clearly shows that during the radical polymerization of the bicyclic monomers 2 and of MDE, respectively, opening of the ketene acetal ring has taken place. For example, the IR spectra of both poly[2] and poly [MDE] show a strong C=O absorption at 1734 cm-'. Moreover, the 13C NMR specta of poly[MDE] also confirms the poly...

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Polymerization of cyclic monomers, 3. Synthesis, radical and cationic polymerization of bicyclic 2‐methylene‐1,3‐dioxepanes

Cited by 21 publications

References 10 publications

Ring-opening polymerization of heterocycles bearing substituted and unsubstituted exo-methylene groups - a review

Ring-opening polymerization of heterocycles bearing substituted and unsubstituted exo-methylene groups - a review

Free radical ring-opening polymerization of cyclic allylic sulfides: Liquid monomers with low polymerization volume shrinkage

Polymerization of Cyclic Monomers. 5. Synthesis and radical polymerization of 4-methylene-3,5-dioxabicyclo[5.1.0]octane

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