Living ring-opening polymerizations of heterocyclic monomers

Penczek, Stanisław; Cypryk, Marek; Duda, Andrzej; Kubisa, Przemysław; Słomkowski, Stanisław

doi:10.1016/j.progpolymsci.2007.01.002

Cited by 343 publications

(254 citation statements)

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“…This phenomenon can be explained by a strong tendency during polymerization to the formation of various macromolecular aggregates containing OK and OH groups with different reactivities [19].…”

Section: Hclmentioning

confidence: 99%

Ring opening polymerization of styrene oxide initiated with potassium alkoxides and hydroxyalkoxides activated by 18-crown-6: determination of mechanism and preparation of new polyether-polyols

et al. 2017

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It was stated that initiation in ring opening polymerization of styrene oxide depends on the kind of potassium alkoxide activated by 18-crown-6 used. In the presence of potassium methoxide the oxirane ring opening occurs exclusively in the b-position and not in the b or a position, i.e., contrary to the previous data. A similar result was obtained in the systems initiated with potassium t-butoxide, 2-methylpropoxide and 1-phenylethoxide. Unexpectedly, potassium i-propoxide and 1-methylpropoxide open the oxirane ring in the b or a position. In all polymerizations, deprotonation of methine group in the monomer takes place under the influence of the initiator and in chain transfer reaction to the monomer. It leads to the formation of macromolecules with unsaturated starting group. However, deprotonation of methylene group in the monomer does not occur. Applying of potassium hydroxyalkoxides, i.e., monopotassium salt of dipropylene glycol or tripotassium salt of 2,2,6,6-tetrakis(hydroxymethyl)cyclohexanol it was possible to synthesize PSO-diols and PSO-pentols without unsaturation. Molar masses of polymers (M n = 1700-4800 Da) are much higher than reported in literature for other anionic systems. Dispersity of polymers is rather low (M w /M n = 1.07-1.15) indicating relatively high rate of initiation and cation exchange reaction.

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Section: Hclmentioning

confidence: 99%

Ring opening polymerization of styrene oxide initiated with potassium alkoxides and hydroxyalkoxides activated by 18-crown-6: determination of mechanism and preparation of new polyether-polyols

et al. 2017

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“…[82][83][84][85][86] However, these often involve stringent polymerization conditions and are restricted to only a few monomers. Recent developments in controlled/living polymerizations such as controlled ring opening polymerization (CROP), 87 atom transfer radical polymerization (ATRP), [88][89][90] nitroxide-mediated radical polymerization (NMP) 91 and reversible addition-fragmentation chain transfer (RAFT) polymerization 92 have provided efficient ways to design and synthesize well defined and complex miktoarm polymers. This is due to a wide variety of applicable monomers and mild polymerization conditions as compared to living anionic polymerization.…”

Section: Challenges In the Synthesis Of Miktoarm Polymersmentioning

confidence: 99%

Dendrimers and miktoarm polymers based multivalent nanocarriers for efficient and targeted drug delivery

et al. 2011

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The delivery of biologically active agents to the desired site in the body and intracellular organelles is still a big challenge despite efforts made for more than five decades. With the elaboration of synthetic methodologies to branched and hyperbranched macromolecules such as miktoarm stars and dendrimers, the focus has shifted to nanocarriers able to release and direct drug molecules to a desired location in a controlled manner. We present here recent developments in the field of targeted drug delivery with a focus on two specific macromolecular nanocarriers, dendrimers and miktoarm stars, and provide examples of these nanocarriers tested in different biological systems. A particular attraction of miktoarm stars is their versatility in achieving superior drug loading within their self-assembled structures. Advantages of dendrimers over linear polymers are that the former provide a platform for development of multivalent and multifunctional nanoconjugates, in addition to their ability to accommodate a large number of molecules inside, or at their surfaces.

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“…Moreover, in 2007 Penczek et al [20] reported in review paper concerning ring-opening polymerization of heterocyclic monomers that the side transfer reaction in propylene oxide polymerization can be depressed to the same extent by counterion complexation with crown ethers. However, the results presented in several works [8,10,[21][22][23] revealed that this effect was observed in the systems containing compounds with OH groups.…”

Section: Introductionmentioning

confidence: 99%

The influence of initiator and macrocyclic ligand on unsaturation and molar mass of poly(propylene oxide)s prepared with various anionic system

et al. 2017

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Anionic polymerization of propylene oxide was carried out in the presence of two groups of potassium salts activated 18-crown-6 (18C6), e.g. alkoxide salts (CH 3 OK, i-PrOK, t-BuOK, CH 3 OCH 2 CH(CH 3 )OK, KCH 2 O) and other salts (CbK, Ph 3 CK, Ph 2 PK, Ph 3 HBK, KK, KH, and [(CH 3 ) 3 Si] 2 NK) in THF at room temperature. Application of various initiating systems results in polyethers which are different in level and kind of unsaturation represented by allyloxy, cis-and trans-propenyloxy, as well as vinyloxy starting groups. In the presence of selected initiator, i.e. t-BuO -K ? unsaturation increases markedly by addition of 18C6 or C222. During the initiation step oxirane ring-opening and direct deprotonation of the monomer occur simultaneously involving in some cases also the ligand. All initiators opens oxirane ring in the b-position except i-PrOK, which opens it in the b-and a-position. The mechanisms of the reactions were discussed.

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Living ring-opening polymerizations of heterocyclic monomers

Cited by 343 publications

References 0 publications

Ring opening polymerization of styrene oxide initiated with potassium alkoxides and hydroxyalkoxides activated by 18-crown-6: determination of mechanism and preparation of new polyether-polyols

Ring opening polymerization of styrene oxide initiated with potassium alkoxides and hydroxyalkoxides activated by 18-crown-6: determination of mechanism and preparation of new polyether-polyols

Dendrimers and miktoarm polymers based multivalent nanocarriers for efficient and targeted drug delivery

The influence of initiator and macrocyclic ligand on unsaturation and molar mass of poly(propylene oxide)s prepared with various anionic system

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