Effect of transfer agent, temperature and initial monomer concentration on branching in poly(acrylic acid): A study by 13 C NMR spectroscopy and capillary electrophoresis

Lena, Jean-Baptiste; Goroncy, Alexander K.; Thevarajah, Joel J.; Maniego, Alison R.; Russell, Gregory T.; Castignolles, Patrice; Gaborieau, Marianne

doi:10.1016/j.polymer.2017.01.030

Cited by 14 publications

(37 citation statements)

References 57 publications

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“…Secondly, in Figure a it is observed that DB is considerably reduced by the presence of CTA and increases with temperature up to 100 °C before remaining the same at 140 °C. The reduction of DB with addition of CTA is by now well known, having already been observed for P n BA and by ourselves with PAA . Again, the most likely reason is the occurrence of a “patching effect,” i.e., a transfer of hydrogen atom between DDM and an MCR.…”

Section: Resultssupporting

confidence: 65%

“…Note that both propagation and termination by combination lead to branched species. When a chain transfer agent (CTA) is present among the reactants, atom transfer from CTA to an MCR may occur, leading to observation of unbranched species . This is called the “patching effect.” All these reactions are presented in Scheme .…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, DB is considerably reduced by the presence of a CTA among the reactants . Two explanations were suggested: either a reduction in backbiting as the polymerization occurs for a shorter time, or transfer from a CTA to the MCR, known as the “patching effect” …”

Section: Introductionmentioning

confidence: 99%

“…Although—as outlined above—there is a reasonable sized body of work on branching in acrylates, including some attention to 2EHA in particular, there are several motivations for the present investigation: As is evident, there is some conflict in the literature: whether branching is present in P2EHA synthesized at low temperature, how the DB of P2EHA compares with that for other acrylates (with the different literature trends giving rise to contrasting mechanistic explanations), and so on; Literature studies have not always been as systematic as one would prefer; Advances in NMR instruments and in understanding of how best to use NMR for branching investigations means that more accurate data may now be obtained; and We would like to build on our preceding study of PAA, in particular with a view to establishing the effect of sidegroup size on DB. For these reasons, the aim of this work was to synthesize P2EHA in bulk at various temperatures (from 4 to 140 °C) both with and without CTA.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Chain Transfer Agent and Temperature on Branching and β‐Scission in Radical Polymerization of 2‐Ethylhexyl Acrylate

Lena

Deschamps

Sciortino

et al. 2018

Macro Chemistry & Physics

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Poly(2‐ethylhexyl acrylate) is synthesized by conventional radical bulk polymerization both with and without 1‐dodecane thiol as chain transfer agent (CTA) at temperatures from 4 to 140 °C. Electrospray‐ionization mass spectrometry is used to analyze the polymer. This reveals the occurrence of significant β‐scission at high temperature and confirms the presence of CTA‐capped polymers at all temperatures, as well as combination products from 4 to 65 °C. Subsequent 13C melt‐state NMR analysis allows quantification of branching and β‐scission. Both are reduced when CTA is present, consistent with a “patching” effect. As expected, the amounts of β‐scission and branching increase with synthesis temperature, although β‐scission dominates at the highest temperature. The backbiting rate coefficient of 2‐ethylhexyl acrylate is determined from NMR results, taking β‐scission into account for the first time. Remarkable agreement with literature kbb values is obtained, especially for activation energy. This strongly suggests family‐type behavior for acrylate kbb.

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Section: Resultssupporting

confidence: 65%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effects of Chain Transfer Agent and Temperature on Branching and β‐Scission in Radical Polymerization of 2‐Ethylhexyl Acrylate

Lena

Deschamps

Sciortino

et al. 2018

Macro Chemistry & Physics

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“…37,38 Recently, among the most extensively used nanoparticles, hyperbranched (HB) polymers, with a structure of highly branched tree-like dendritic material containing numerous -OH end groups, have been used in hydrogels. [39][40][41] In a hydrogel crosslinked with HB polymers, polymeric chains have been held together by directionally discrete supramolecular binding sites to enhance the mechanical properties of the resultant composite. 42,43 Evidence has suggested the potential for using HB polymers as a reinforcement agent in PAA based hydrogels.…”

Section: à2mentioning

confidence: 99%

In situ polymerized hyperbranched polymer reinforced poly(acrylic acid) hydrogels

Dehbari

Tavakoli

Khatrao

et al. 2017

Mater. Chem. Front.

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a Hydrogels have been extensively investigated for use in various applications. Poly acrylic acid (PAA) is a common example, which has been widely used due to its super hydrophilicity properties, biocompatibility and biodegradability characteristics. However its poor mechanical properties, which have been addressed in many research studies, are known as a drawback that limits its applications. So, enhancing PAA mechanical properties using a hyperbranched polymer (HB) is the key question to be addressed in this research.Investigations of the mechanical properties of the PAA-HB hydrogel revealed 130% improvement in the ultimate tensile strength, indicating a two times enhancement compared to that of PAA. Statistical analysis showed that the overall effect of introducing notches (with different depths) on the selected mechanical properties of both PAA and PAA-HB was significant. Mechanical characterization of PAA-HB networks showed that significant improvement in the mechanical properties was achieved as the capability of water uptake increased by 20%. Characterization of the physical properties confirmed that participation of HB may form a PAA based hybrid material with good swelling properties. Those findings are attributed to the supramolecular structure of the HB, which can introduce physical entanglement between the PAA network structure and increase the crystallinity of the final hydrogel as compared to those from the PAA hydrogel.

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Using Capillary Electrophoresis to Investigate Protein Conformational and Compositional Heterogeneity

Grosas,

Du Plessis,

Thevarajah

et al. 2024

ChemBioChem

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Detailed insights into protein structure/function relationships require robust characterization methodologies. Free‐solution capillary electrophoresis (CE) is a unique separation technique which is sensitive to the conformation and/or composition of proteins, and therefore provides information on the heterogeneity of these properties. Three unrelated, conformationally/compositionally‐altered proteins were separated by CE. An electrophoretic mobility distribution was determined for each protein along with its conformational and/or compositional heterogeneity. CE results were compared with molar mass distributions obtained from size‐exclusion chromatography coupled to light scattering (SEC‐MALS). Bovine serum albumin oligomers and two monomeric species were separated, highlighting variations in conformational/compositional heterogeneity among the oligomers. Analysis of yeast alcohol dehydrogenase resolved two monomeric conformers and various tetrameric species, illustrating the impact of zinc ion removal and disulfide bond reduction on the protein’s heterogeneity. The apo (calcium‐free) and holo forms of bovine α‐lactalbumin were separated and differences in the species’ heterogeneity was measured; by contrast, the SEC‐MALS profiles were identical. Comparative analysis of these structurally unrelated proteins provided novel insights into the interplay between molar mass and conformational/compositional heterogeneity. Overall, this study expands the utility of CE by demonstrating its capacity to discern protein species and their heterogeneity, properties which are not readily accessible by other analytical techniques.

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Effect of transfer agent, temperature and initial monomer concentration on branching in poly(acrylic acid): A study by 13 C NMR spectroscopy and capillary electrophoresis

Cited by 14 publications

References 57 publications

Effects of Chain Transfer Agent and Temperature on Branching and β‐Scission in Radical Polymerization of 2‐Ethylhexyl Acrylate

Effects of Chain Transfer Agent and Temperature on Branching and β‐Scission in Radical Polymerization of 2‐Ethylhexyl Acrylate

In situ polymerized hyperbranched polymer reinforced poly(acrylic acid) hydrogels

Using Capillary Electrophoresis to Investigate Protein Conformational and Compositional Heterogeneity

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