The poly(propylene oxide-<i>co</i>-ethylene oxide) gradient is controlled by the polymerization method: determination of reactivity ratios by direct comparison of different copolymerization models

Blankenburg, Jan; Kersten, Erik; Maciol, Kamil; Wagner, Manfred; Zarbakhsh, Sirus; Frey, Holger

doi:10.1039/c9py00500e

Cited by 50 publications

(74 citation statements)

References 46 publications

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“…3). 53 Importantly due to the truly living nature of anionic polymerisation, 57,58 full monomer conversions were achieved and excellent end-group delity could be maintained, allowing access to diblock copolymers in one pot. 59 In 2019, the same group also presented a theoretical model that enables the accurate prediction of MWD composition for a range of initiator addition proles when polystyrene was synthesised by anionic polymerisation.…”

Section: Temporal Regulation Of Initiationmentioning

confidence: 99%

Tailoring polymer dispersity and shape of molecular weight distributions: methods and applications

et al. 2019

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Section: Temporal Regulation Of Initiationmentioning

confidence: 99%

Tailoring polymer dispersity and shape of molecular weight distributions: methods and applications

et al. 2019

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“…The reactivity ratios were determined by fitting the in situ data to the ideal copolymerization model to be r EPB = 0.35 and r EO = 2.8 ( Figure S33, Supporting Information). [29] The results were confirmed by classical aliquot takinga td etermined points in time from the bulk polymerization reaction. Based on these reactivity ratios the averagem icrostructure was depicted for ac opolymer started by ab ifunctionalinitiator with the same compositiona sP (EG 168 -co-EPB 13 ), see Figure1c.…”

Section: Characterizationmentioning

confidence: 56%

“…To comprehend the monomer sequence distribution during anionic ring‐opening copolymerization, on‐line 1 H NMR measurements—a technique that has been proven extremely useful to monitor polymerization reactions in situ—has been employed during copolymerization of EPB and EO. The reactivity ratios were determined by fitting the in situ data to the ideal copolymerization model to be r EPB =0.35 and r EO =2.8 (Figure S33, Supporting Information) …”

Section: Resultsmentioning

confidence: 99%

Acid‐Cleavable Poly(ethylene glycol) Hydrogels Displaying Protein Release at pH 5

Johannes

Blankenburg

Worm

et al. 2020

Chemistry A European J

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PEG is the gold standard polymer for pharmaceutical applications, however it lacks degradability. Degradation under physiologically relevant pH as present in endolysosomes, cancerous and inflammatory tissues is crucial for many areas. The authors present anionic ring‐opening copolymerization of ethylene oxide with 3,4‐epoxy‐1‐butene (EPB) and subsequent modification to introduce acid‐degradable vinyl ether groups as well as methacrylate (MA) units, enabling radical cross‐linking. Copolymers with different molar ratios of EPB, molecular weights (Mn) up to 10 000 g mol−1 and narrow dispersities (Đ<1.05) were prepared. Both the P(EG‐co‐isoEPB)MA copolymer and the hydrogels showed pH‐dependent, rapid hydrolysis at pH 5–6 and long‐term storage stability at neutral pH (pH 7.4). By designing the degree of polymerization and content of degradable vinyl ether groups, the release time of an entrapped protein OVA‐Alexa488 can be tailored from a few hours to several days (hydrolysis half‐life time t1/2 at pH 5: 13 h to 51 h).

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“…The high reactivity difference between the two monomers during copolymerization was also confirmed by the reactivity ratios ( r 1 =19 and r 2 =0.052 for M1 / M2 , Table S1) calculated by ideal integrated equation . The microstructure of the block‐like copolymer of M1 and M2 was visualized by using the reactivity ratios (Figure a, bottom).…”

Section: Methodsmentioning

confidence: 62%

One‐Step Ring Opening Metathesis Block‐Like Copolymers and their Compositional Analysis by a Novel Retardation Technique

et al. 2020

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Using a one‐step synthetic route for block copolymers avoids the repeated addition of monomers to the polymerization mixture, which can easily lead to contamination and, therefore, to the unwanted termination of chain growth. For this purpose, monomers (M1–M5) with different steric hindrances and different propagation rates are explored. Copolymerization of M1 (propagating rapidly) with M2 (propagating slowly), M1 with M3 (propagating extremely slowly) and M4 (propagating rapidly) with M5 (propagating slowly) yielded diblock‐like copolymers using Grubbs’ first (G1) or third generation catalyst (G3). The monomer consumption was followed by 1H NMR spectroscopy, which revealed vastly different reactivity ratios for M1 and M2. In the case of M1 and M3, we observed the highest difference in reactivity ratios (r1=324 and r2=0.003) ever reported for a copolymerization method. A triblock‐like copolymer was also synthesized using G3 by first allowing the consumption of the mixture of M1 and M2 and then adding M1 again. In addition, in order to measure the fast reaction rates of the G3 catalyst with M1, we report a novel retardation technique based on an unusual reversible G3 Fischer‐carbene to G3 benzylidene/alkylidene transformation.

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The poly(propylene oxide-co-ethylene oxide) gradient is controlled by the polymerization method: determination of reactivity ratios by direct comparison of different copolymerization models

Abstract: An investigation of the copolymerization of EO and PO by in situ1H NMR spectroscopy reveals striking differences in the monomer gradient, depending on the polymerization method.

Cited by 50 publications

References 46 publications

Tailoring polymer dispersity and shape of molecular weight distributions: methods and applications

Tailoring polymer dispersity and shape of molecular weight distributions: methods and applications

Acid‐Cleavable Poly(ethylene glycol) Hydrogels Displaying Protein Release at pH 5

One‐Step Ring Opening Metathesis Block‐Like Copolymers and their Compositional Analysis by a Novel Retardation Technique

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