Synthesis and Topological Trapping of Cyclic Poly(alkylene phosphates)

Stukenbroeker, Tyler S.; Solis‐Ibarra, Diego; Waymouth, Robert M.

doi:10.1021/ma501764c

Cited by 52 publications

(36 citation statements)

References 48 publications

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“…The cyclic phosphate 2‐isopropoxy‐2‐oxo‐1,3,2‐dioxa‐phospholane (iPP) can be polymerized using highly active NHCs and other organocatalysts such as DBU or 1,5,7‐triazabicyclo[4.4.0]undec‐5‐ene (TBD) to give cyclic poly(iPP) in the absence of alcohol initiators . The cyclic nature of the poly(iPP) was exploited by physically trapping (i.e., “topological entrapment”) the polymers in a crosslinked 2‐hydroxyethyl methacrylate (HEMA) hydrogel.…”

Section: Ring‐expansion Polymerizationmentioning

confidence: 99%

Recent progress on the synthesis of cyclic polymers via ring‐expansion strategies

Chang

Waymouth

2017

J. Polym. Sci. Part A: Polym. Chem.

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129

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Cyclic polymers are the simplest topological isomers of linear macromolecules, but exhibit properties that differ from linear chains in ways that remain imperfectly understood. The difficulty of synthesizing appropriately pure and high molecular weight cyclic samples has hindered experimental studies. Ringclosure methods, while versatile, are inherently limited in the range of molecular weights that can be achieved. Ringexpansion methods are a much more promising strategy toward obtaining high molecular weight cyclic polymers. The current review focuses on recent developments in ring-expansion polymerization strategies toward the synthesis of high molecular weight cyclic polymers. Significant progress in the last decade has made the synthesis of cyclic polymers possible by a variety of methods, such as ruthenium-and tungsten-catalyzed ringexpansion metathesis polymerization, organocatalytic and Lewis acid-catalyzed zwitterionic polymerization, RAFT and nitroxidemediated radical polymerization, among many others. While the study of cyclic polymers has long been hampered by synthetic challenges, the recent resurgence of interest in this field presents an exciting opportunity for chemists. V C 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 2892-2902 KEYWORDS: cationic polymerization; cyclic polymers; cyclopolymerization; Grubbs catalyst; macrocycles; macrocyclic polymerization; metathesis polymerization; ring-expansion polymerization; zwitterionic polymerization INTRODUCTION Most of our knowledge of the physical and dynamic properties of polymers derives from investigations of linear chain macromolecules. Cyclic polymers, topological isomers of linear chains, differ from their linear congeners by only one bond, and yet this topological difference leads to behavior that, in many respects, remains poorly understood. Early heroic synthetic efforts to generate and investigate high molecular weight cyclic macromolecules 1-4 were compromised by the dramatic influence of even minor amounts of linear contaminants on the properties (esp. rheological properties) of cyclic chains. 1,[5][6][7] The synthesis of cyclic macromolecules of sufficient quantity and purity has proven to be a formidable challenge and has imposed a significant limitation on the study of their behavior as a function of molecular weight. Until recently, only a limited number of different classes of cyclic polymers have been prepared and investigated. Nevertheless, these pioneering studies have shown that cyclic polymers behave in a way that can be quite different from their linear counterparts despite their nearidentical chemical compositions. Cyclic polymers, for instance, cannot reptate or entangle 3,5,7,8 in the same way that linear polymers do and have a smaller radius of gyration in solution, leading to lower solution viscosities. 1,6

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Section: Ring‐expansion Polymerizationmentioning

confidence: 99%

Recent progress on the synthesis of cyclic polymers via ring‐expansion strategies

Chang

Waymouth

2017

J. Polym. Sci. Part A: Polym. Chem.

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129

125

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“…Top: copolymerization of lactams using an NHC–CO 2 adduct . Bottom: preparation of high‐ M w macrocyclic poly(iPP) …”

Section: Ring‐opening Polymerizationsmentioning

confidence: 99%

“…67 Bottom: preparation of high-M w macrocyclic poly(iPP). 68 reported (Scheme 8, top). 59 Using the electron-rich and weakly congested NHC 5 Me -iPr in toluene with co-initiating alcohols, a degree of polymerization of 100 was achieved in less than a minute (99% yield).…”

Section: Rop Of Siloxanes and Carbonatesmentioning

confidence: 99%

N‐Heterocyclic carbenes for metal‐free polymerization catalysis: an update

Naumann

Dove

2015

Polymer International

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This mini‐review is intended to serve as a concise introduction to polymerizations that are catalysed by N‐heterocyclic carbenes. The content is structured according to accessible monomer functionalities and type of polymerization. Both major achievements as well as the latest developments in this rapidly evolving field are presented. A broad range of different types of monomers is covered in this way, including among others lactones, epoxides, anhydrides, acrylates, siloxanes and lactams. Special emphasis is put on mechanistic understanding and structure–activity relationships. © 2015 Society of Chemical Industry

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“…[5][6][7][8][9][10][11][12][13] We have reported a zwitterionic 14 ring-opening polymerization strategy 15 for the synthesis of cyclic polymers from lactones, [16][17][18][19][20][21][22][23] cyclic phosphates, 24 and carbosiloxanes; 25 Zhang has shown this strategy is also effective for generating cyclic poly( peptoid)s. 26 N-heterocyclic carbenes (NHC) have proven useful as intiators for ZROP due to the ability to tune the reactivity of the carbene to that of the monomer. NHC-mediated ZROP has recently been reported in the synthesis of ultra-high molecular weight cyclic polymers up to >900 kDa.…”

Section: Introductionmentioning

confidence: 99%

Ion pairing effects in the zwitterionic ring opening polymerization of δ-valerolactone

Chang

Waymouth

2015

Polym. Chem.

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The ring-opening polymerization (ZROP) of δ-valerolactone (VL) by N-heterocyclic carbenes (NHC) in the absence of alcohol initiators generates cyclic poly(valerolactones). A zwitterionic mechanism has been proposed where the propagating alkoxide anion undergoes ion-pairing with the acyl-imidazolium polymer chain end. To evaluate the consequences of zwitterionic ion-pairing, the influence of added LiCl to the NHC-mediated ZROP of δ-valerolactone (VL) in THF was investigated. In THF in the absence of LiCl, the molecular weights of the resultant p(VL) are higher than that predicted from the initial ratio of [VL] 0 /[NHC] 0 and the molecular weight distributions are bimodal and broad (M w /M n = 1.35). In the presence of 1.0 M LiCl, the molecular weights of the p(VL) match that predicted from [VL] 0 /[NHC] 0 and the molecular weight distributions are monomodal and narrow (M w /M n = 1.08-1.26). The presence of LiCl also influences both the rate of polymerization and the topology of the resultant poly(valerolactones). In the absence of LiCl, cyclic poly(valerolactones) are isolated upon aqueous methanol work-up, but at high LiCl concentrations, only linear chains are produced. These results imply that zwitterionic ion-pairs can be readily broken up by added LiCl.

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Synthesis and Topological Trapping of Cyclic Poly(alkylene phosphates)

Cited by 52 publications

References 48 publications

Recent progress on the synthesis of cyclic polymers via ring‐expansion strategies

Recent progress on the synthesis of cyclic polymers via ring‐expansion strategies

N‐Heterocyclic carbenes for metal‐free polymerization catalysis: an update

Ion pairing effects in the zwitterionic ring opening polymerization of δ-valerolactone

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