The Chemistry of 2‐Alkenyl‐5(4H)‐ oxazolones. IX. Acid‐Catalyzed Oligomerization

Heilmann, Steven M.; Moren, D. M.; Krepski, Larry R.; Rasmussen, Jerald K.; Gaddam, Babu N.; Roscoe, Stephen B.; Lewandowski, Kevin; McIntosh, Lester H.; Roberts, Ralph R.; Fansler, Duane D.; Szekely, Gabriella G.; Weil, David A.; Thakur, Khalid A. M.; Pathre, S. V.; Battiste, John L.; Hanggi, Douglas A.

doi:10.1081/ma-120022270

Cited by 3 publications

(16 citation statements)

References 16 publications

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“…Characterization of these precipitates using liquid chromatography-mass spectrometry (LC-MS) revealed a range of structures having the molecular weights shown in Table S1 of the Supporting Information. These molecular weights correspond to a mixture of VDMA-based oligomers composed of dimers through hexamers (with varying degrees of hydrolysis) that was similar to the results reported previously by Heilmann et al32 Similar precipitation experiments using samples of freshly distilled VDMA monomer revealed these samples to be devoid of oligomers.…”

Section: Resultssupporting

confidence: 88%

“…)33–35 We note in this context, that these cyclic oligomers are not functionalized with vinyl groups (e.g., see structures shown in Figure S2 of the Supporting Information). We note further, however, that Heilmann et al have proposed enol tautomers as intermediates during the formation of these oligomers32 and that, if present, these enol tautomers could potentially be incorporated into a growing polymer chain during free radical polymerization. Another possibility is that these oligomers could behave as chain transfer or chain termination agents during polymerization.…”

Section: Resultsmentioning

confidence: 62%

“…These reactions do not occur through a chain growth-type mechanism to yield short chains of PVDMA, but rather proceed by protonation of the azlactone nitrogen of VDMA followed by Michael addition to the olefin to form cyclic structures containing, most often, four, five, or six monomer units (although higher order oligomers can also be formed). A complete analysis of these oligomeric structures and a detailed discussion of the mechanism of formation of these oligomers have been reported previously (see also Figures S1 and S2 of the Supporting Information for the proposed mechanism and the structures of the oligomeric compounds that form) 32. To determine whether our non-distilled supply of VDMA contained these oligomerization products, we added aliquots of a PVDMA ND solution drop-wise to heptane (following a protocol reported by Heilmann et al for the isolation of oligomers from VDMA)32 and observed the formation of a precipitate.…”

Section: Resultsmentioning

confidence: 94%

“…We synthesized authentic samples of oligomer under controlled conditions by treating freshly distilled VDMA with TFA (see Materials and Methods for additional details) 32. LC-MS characterization of samples of the resulting oligomers revealed them to be composed of a mixture of trimers, tetramers, pentamers, and hexamers (see Table S2 of the Supporting Information for additional details related to the characterization of these independently-synthesized oligomers).…”

Section: Resultsmentioning

confidence: 99%

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Superhydrophobic Thin Films Fabricated by Reactive Layer-by-Layer Assembly of Azlactone-Functionalized Polymers

Buck

Schwartz²,

Lynn³

2010

Chem. Mater.

100

130

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We report an approach to the fabrication of superhydrophobic thin films that is based on the 'reactive' layer-by-layer assembly of azlactone-containing polymer multilayers. We demonstrate that films fabricated from alternating layers of the azlactone functionalized polymer poly(2-vinyl-4,4-dimethylazlactone) (PVDMA) and poly(ethyleneimine) (PEI) exhibit micro-and nanoscale surface features that result in water contact angles in excess of 150º. Our results reveal that the formation of these surface features is (i) dependent upon film thickness (i.e., the number of layers of PEI and PVDMA deposited) and (ii) that it is influenced strongly by the presence (or absence) of cyclic azlactone-functionalized oligomers that can form upon storage of the 2-vinyl-4,4-dimethylazlactone (VDMA) used to synthesize PVDMA. For example, films fabricated using polymers synthesized in the presence of these oligomers exhibited rough, textured surfaces and superhydrophobic behavior (i.e., advancing contact angles in excess of 150º). In contrast, films fabricated from PVDMA polymerized in the absence of this oligomer (e.g., using freshly distilled monomer) were smooth and only moderately hydrophobic (i.e., advancing contact angles of ~75º). The addition of authentic, independently synthesized oligomer to samples of distilled VDMA at specified and controlled concentrations permitted reproducible fabrication of superhydrophobic thin films on the surfaces of a variety of different substrates. The surfaces of these films were demonstrated to be superhydrophobic immediately after fabrication, but they became hydrophilic after exposure to water for six days. Additional experiments demonstrated that it was possible to stabilize and prolong the superhydrophobic properties of these films (e.g., advancing contact angles in excess of 150° even after complete submersion in water for at least six weeks) by exploiting the reactivity of residual azlactones to functionalize the surfaces of the films using hydrophobic amines (e.g., aliphatic or semi-fluorinated aliphatic amines). Our results demonstrate a straightforward and substrate-independent approach to the design of superhydrophobic and reactive polymer-based coatings of potential use in a broad range of fundamental and applied contexts.

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Section: Resultssupporting

confidence: 88%

Section: Resultsmentioning

confidence: 62%

Section: Resultsmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 99%

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Superhydrophobic Thin Films Fabricated by Reactive Layer-by-Layer Assembly of Azlactone-Functionalized Polymers

Buck

Schwartz²,

Lynn³

2010

Chem. Mater.

100

130

View full text Add to dashboard Cite

show abstract

“…76 Subsequent characterization of the water contact angles of these films, as-fabricated, revealed them to exhibit advancing water contact angles in excess of 150 . The results of several experiments revealed that this surface roughness was dependent upon both film thickness and the presence of cyclic azlactone-functionalized oligomers that have been reported to form, under certain conditions, 81 upon storage of VDMA (films fabricated using PVDMA synthesized using freshly distilled monomer were smooth and exhibited contact angles of $75 ).…”

Section: Fabrication Of Multicomponent Thin Filmsmentioning

confidence: 99%

Azlactone-functionalized polymers as reactive platforms for the design of advanced materials: Progress in the last ten years

2012

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Polymers functionalized with azlactone (or oxazolone) functionality have become increasingly useful for the rapid and modular design of functional materials. Because azlactones can react via ring-opening reactions with a variety of different nucleophilic species (e.g., primary amines, hydroxyl groups, and thiol functionality), azlactone-functionalized materials can serve as convenient ‘reactive’ platforms for the post-synthesis or post-fabrication introduction of a broad range of chemical functionality to soluble polymers, insoluble supports, and surfaces/interfaces. The last decade has seen an increase in both the number and the variety of reports that exploit the properties and the reactivities of azlactone-functionalized polymers. Here, we highlight recent work from several different laboratories, including our own, toward the design and characterization of azlactone-functionalized polymers, with a particular emphasis on: (i) new synthetic approaches for the preparation of well-defined azlactone-functionalized polymers using living/controlled methods of polymerization, (ii) the design and modular synthesis of side-chain functionalized polymers and block copolymers via post-polymerization modification of azlactone-functionalized polymers, (iii) the development of reactive polymeric supports useful in the contexts of separations and catalysis, and (iv) methods for the fabrication of reactive thin films and other approaches to the immobilization of azlactone functionality on surfaces and interfaces. Examples discussed herein reveal a growing awareness of azlactone functionality as a useful tool for polymer chemists, and highlight several ways that the unique reactivity of these materials can both complement and provide useful alternatives to other reactive polymers currently used to design functional materials.

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Influence of Side Chain Hydrolysis on the Evolution of Nanoscale Roughness and Porosity in Amine-Reactive Polymer Multilayers

et al. 2020

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We report the influence of side chain hydrolysis on the evolution of nanoscale structure in thin films fabricated by the reactive layer-by-layer (LbL) assembly of branched poly(ethylenimine) (PEI) and poly(2-vinyl-4,4-dimethylazlactone) (PVDMA). LbL assembly of PEI and PVDMA generally leads to the linear growth of thin, smooth films. However, assembly using PVDMA containing controlled degrees of side chain hydrolysis leads to the growth of thicker films that exhibit substantial nanoscale roughness, porosity, and have resulting physicochemical behaviors (e.g., superhydrophobicity) that are similar to those of some thicker PEI/PVDMA coatings reported in past studies. Our results reveal that the degree of PVDMA partial hydrolysis (or carboxylic acid group content) influences the extent to which complex film features develop, suggesting that ion-pairing interactions between hydrolyzed side chains and amines in PEI promote the evolution of bulk and surface morphology. Additional experiments demonstrate that these features likely arise from polymer/polymer interactions at the surfaces of the films during assembly, and not from the formation and deposition of solution-phase polymer aggregates. When combined, our results suggest that nanoporous structures and rough features observed in past studies likely arise, at least in part, from some degree of adventitious side chain hydrolysis in the PVDMA used for film fabrication. Our results provide useful insight into molecular-level features that govern the growth and structures of these reactive materials, and provide a framework to promote nanoscale morphology reliably and reproducibly. The principles and tools reported here should prove useful for further tuning the porosities and tailoring the physicochemical behaviors of these reactive coatings in ways that are important in applied contexts.

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The Chemistry of 2‐Alkenyl‐5(4H)‐ oxazolones. IX. Acid‐Catalyzed Oligomerization

Cited by 3 publications

References 16 publications

Superhydrophobic Thin Films Fabricated by Reactive Layer-by-Layer Assembly of Azlactone-Functionalized Polymers

Superhydrophobic Thin Films Fabricated by Reactive Layer-by-Layer Assembly of Azlactone-Functionalized Polymers

Azlactone-functionalized polymers as reactive platforms for the design of advanced materials: Progress in the last ten years

Influence of Side Chain Hydrolysis on the Evolution of Nanoscale Roughness and Porosity in Amine-Reactive Polymer Multilayers

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