Entropy‐Driven Selectivity for Chain Scission: Where Macromolecules Cleave

Pahnke, Kai; Brandt, Josef; Gryn’ova, Ganna; Lin, Ching Yeh; Altintas, Ozcan; Schmidt, Friedrich Georg; Lederer, Albena; Coote, Michelle L.; Barner‐Kowollik, Christopher

doi:10.1002/anie.201508531

Cited by 29 publications

(20 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The observed decrease in molecular weight is due to polymer backbone cleavage in the middle of the chain being more entropically favored as opposed to backbone cleavage closer to the polymer chain ends. [ 34,35 ] Consistent with this, the number average molecular weights ( M n ) significantly decreased between plasma‐treated groups and the raw, non‐treated sample ( n = 3, p < 0.05) (Figure 4b).…”

Section: Resultssupporting

confidence: 67%

Degradation of Melt Electrowritten PCL Scaffolds Following Melt Processing and Plasma Surface Treatment

Paxton

Tuten

et al. 2021

Macromol. Rapid Commun.

View full text Add to dashboard Cite

Melt electrowriting (MEW) has been widely used to process polycaprolactone (PCL) into highly ordered microfiber scaffolds with controllable architecture and geometry. However, the integrity of PCL during specific processes involved in routine MEW scaffold development has not yet been thoroughly investigated. This study investigates the impact of MEW processing on PCL following exposure to high temperatures required for melt extrusion as well as atmospheric plasma, a widely used surface treatment for improving MEW scaffold hydrophilicity. The change in polymer molecular weight and melt temperature is characterized, in comparing unprocessed and processed samples, in addition to analysis of the mechanical and surface properties of the scaffolds. No significant difference in the molecular weight or mechanical properties of the PCL scaffolds is evident following 5 days of cyclic heating to 90 °C. Exposure to plasma for up to 5 min significantly increased hydrophilicity and surface adhesion force, characterized via contact angle and atomic force microscope, however, significant polymer degradation occurred evidenced by increased brittleness of the scaffolds. This study demonstrates the degradation of PCL following fabrication via MEW and surface treatment to guide the optimization of scaffold development for subsequent applications in tissue engineering and biofabrication.

show abstract

Section: Resultssupporting

confidence: 67%

Degradation of Melt Electrowritten PCL Scaffolds Following Melt Processing and Plasma Surface Treatment

Paxton

Tuten

et al. 2021

Macromol. Rapid Commun.

View full text Add to dashboard Cite

show abstract

“…Submitting polyolefins to extru sion at 200-300 o C results in chain scis sions [13] which generate carboncentered (Ccentered) radicals. The question, at which place along the chain does the mac romolecule cleave, has been discussed [14] very recently. As a consequence, the mo lecular weight of polypropylene (PP) de creases during the extrusion, whereas in polyethylene chain scissions and cross linking via addition of macroradicals to the remaining vinyl groups, present from the polymerization process, may occur si multaneously as competitive reactions.…”

Section: Radicals In the Degradation Of Polymersmentioning

confidence: 99%

Radicals and Polymers

Nesvadba¹

2018

Chimia

View full text Add to dashboard Cite

This article describes some selected results of my 30 years as an industrial researcher. During this time, I had the chance to work on many very different projects. About two thirds of them were dealing with the fascinating interaction of radicals and polymers. Of the more than 350 million tons of industrial polymers produced worldwide every year, about 50% are made by the radical polymerization of monomers that are often stabilized against undesired premature polymerization by addition of polymerization inhibitors. Stabilizers are necessary to protect the majority of polymeric materials during their service life from radical degradation processes triggered by oxygen, heat or light. Modification of the polymeric architecture can be easily achieved via radical polymer analogous reactions. One of the most important developments in polymer science in the last 25 years is controlled radical polymerization. Recently, radical bearing redox-active polymers emerged as promising in energy storage applications, for example, in organic radical batteries. Our contributions to the fields mentioned above are described with examples of: a) novel benzofuranone stabilizers for polymers; b) the serendipidous discovery of novel dyestuffs; c) eco-friendly polymerization inhibitors; d) novel nitroxides and alkoxyamines for the first industrial realization of controlled radical polymerization; e) novel and safe radical initiators; f) nitroxide radicals bearing polymers for electrochemical applications.

show abstract

“…She is also interested in electrochemistry, organocatalysis, self‐healing materials, photochemistry, and autoxidation. She has reported in Angewandte Chemie on polymer chain cleavage, and is co‐author of a report in Chemistry—An Asian Journal on the synthesis and structure of rezishanone C…”

Section: Awarded …mentioning

confidence: 99%

Royal Australian Chemical Institute Awards

2017

Angew Chem Int Ed

View full text Add to dashboard Cite

Entropy‐Driven Selectivity for Chain Scission: Where Macromolecules Cleave

Cited by 29 publications

References 37 publications

Degradation of Melt Electrowritten PCL Scaffolds Following Melt Processing and Plasma Surface Treatment

Degradation of Melt Electrowritten PCL Scaffolds Following Melt Processing and Plasma Surface Treatment

Radicals and Polymers

Royal Australian Chemical Institute Awards

Contact Info

Product

Resources

About