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Poon L, Hum JR, Weiss RG. Effects of cyclic and acyclic amidine side-chains on the properties of polysiloxane ionomers constructed in situ from three uncharged components. SOFT MATTER 2022; 18:5502-5508. [PMID: 35848508 DOI: 10.1039/d2sm00382a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Ionomers, polysiloxanes with imidazolinium dithiocarbamate side chains, have been synthesized in situ from three uncharged components-a polysiloxane with imidazole side chains, CS2, and hexylamine or octadecylamine. Their structural and dynamic properties are compared over a temperature range of 0-50 °C with those of the analogous ionomers in which the polysiloxanes have amidinium side chains. The results, primarily from differential scanning calorimetry, powder X-ray diffraction measurements, and rheology show that the small structural (and smaller electronic) differences between the cyclic 5-membered ring imidazolinium and acyclic amidinium groups have marked effects on the bulk properties of the ionomers. These include their shear strengths and the manner in which the microcrystalline portions of the ionomers with dithiooctadecylcarbamate anions are packed. Thus, it is possible to finely tune the natures of the ionomers from one polysiloxane by changing temperature, the chain length of the alkylamine, and the nature of the base attached to the polysiloxane chain. Why these changes occur to the various properties is discussed.
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Affiliation(s)
- Louis Poon
- Department of Chemistry and Institute for Soft Matter Synthesis and Metrology, Georgetown University, Washington, DC 20057-1227, USA.
| | - Jacob R Hum
- Department of Chemistry and Institute for Soft Matter Synthesis and Metrology, Georgetown University, Washington, DC 20057-1227, USA.
| | - Richard G Weiss
- Department of Chemistry and Institute for Soft Matter Synthesis and Metrology, Georgetown University, Washington, DC 20057-1227, USA.
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Poon L, Weiss RG. Uncharged Lewis bases yield polydimethylsiloxane ionomers with amidinium alkyldithiocarbamate side chains. JOURNAL OF POLYMER SCIENCE 2021. [DOI: 10.1002/pol.20210473] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Louis Poon
- Department of Chemistry, Institute for Soft Matter Synthesis and Metrology, Georgetown University Washington DC USA
| | - Richard G. Weiss
- Department of Chemistry, Institute for Soft Matter Synthesis and Metrology, Georgetown University Washington DC USA
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Nasr P, Leung H, Auzanneau FI, Rogers MA. Supramolecular Fractal Growth of Self-Assembled Fibrillar Networks. Gels 2021; 7:gels7020046. [PMID: 33919860 PMCID: PMC8167784 DOI: 10.3390/gels7020046] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 04/09/2021] [Accepted: 04/12/2021] [Indexed: 11/16/2022] Open
Abstract
Complex morphologies, as is the case in self-assembled fibrillar networks (SAFiNs) of 1,3:2,4-Dibenzylidene sorbitol (DBS), are often characterized by their Fractal dimension and not Euclidean. Self-similarity presents for DBS-polyethylene glycol (PEG) SAFiNs in the Cayley Tree branching pattern, similar box-counting fractal dimensions across length scales, and fractals derived from the Avrami model. Irrespective of the crystallization temperature, fractal values corresponded to limited diffusion aggregation and not ballistic particle–cluster aggregation. Additionally, the fractal dimension of the SAFiN was affected more by changes in solvent viscosity (e.g., PEG200 compared to PEG600) than crystallization temperature. Most surprising was the evidence of Cayley branching not only for the radial fibers within the spherulitic but also on the fiber surfaces.
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Affiliation(s)
- Pedram Nasr
- Department of Food Science, University of Guelph, Guelph, ON N1G 2W1, Canada; (P.N.); (H.L.)
| | - Hannah Leung
- Department of Food Science, University of Guelph, Guelph, ON N1G 2W1, Canada; (P.N.); (H.L.)
| | | | - Michael A. Rogers
- Department of Food Science, University of Guelph, Guelph, ON N1G 2W1, Canada; (P.N.); (H.L.)
- Correspondence: ; Tel.: +11-519-824-4120 (ext. 54327)
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Lan Y, Lv M, Guo S, Nasr P, Ladizhansky V, Vaz R, Corradini MG, Hou T, Ghazani SM, Marnangoni A, Rogers MA. Molecular motifs encoding self-assembly of peptide fibers into molecular gels. SOFT MATTER 2019; 15:9205-9214. [PMID: 31710326 DOI: 10.1039/c9sm01793c] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Peptides are a promising class of gelators, due to their structural simplicity, biocompatibility and versatility. Peptides were synthesized based on four amino acids: leucine, phenylalanine, tyrosine and tryptophan. These peptide gelators, with systematic structural variances in side chain structure and chain length, were investigated using Hansen solubility parameters to clarify molecular features that promote gelation in a wide array of solvents. It is of utmost importance to combine both changes to structural motifs and solvent in simultaneous studies to obtain a global perspective of molecular gelation. It was found that cyclization of symmetric dipeptides, into 2,5-diketopiperazines, drastically altered the gelation ability of the dipeptides. C-l-LL and C-l-YY, which are among the smallest peptide LMOGs reported to date, are robust gelators with a large radius of gelation (13.44 MPa1/2 and 13.90 MPa1/2, respectively), and even outperformed l-FF (5.61 MPa1/2). Interestingly, both linear dipeptides (l-FF and l-LL) gelled similar solvents, yet when cyclized only cyclo-dityrosine was a robust gelator, while cyclo-diphenylalanine was not. Changes in the side chains drastically affected the crystal morphology of the resultant gels. Symmetric cyclo dipeptides of leucine and tyrosine were capable of forming extremely high aspect ratio fibers in numerous solvents, which represent new molecular motifs capable of driving self-assembly.
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Affiliation(s)
- Yaqi Lan
- Guangdong Provincial Key Laboratory of Nutraceuticals and Functional Foods, College of Food Sciences, South China Agricultural University, Guangzhou, Guangdong, P. R. China
| | - Muwen Lv
- Guangdong Provincial Key Laboratory of Nutraceuticals and Functional Foods, College of Food Sciences, South China Agricultural University, Guangzhou, Guangdong, P. R. China
| | - Shenglan Guo
- Guangdong Provincial Key Laboratory of Nutraceuticals and Functional Foods, College of Food Sciences, South China Agricultural University, Guangzhou, Guangdong, P. R. China
| | - Pedram Nasr
- Department of Food Science, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
| | | | - Raoul Vaz
- Department of Physics, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Maria G Corradini
- Department of Food Science, University of Guelph, Guelph, Ontario N1G 2W1, Canada. and Arrell Food Institute, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Tao Hou
- Guangdong Provincial Key Laboratory of Nutraceuticals and Functional Foods, College of Food Sciences, South China Agricultural University, Guangzhou, Guangdong, P. R. China
| | - Saeed M Ghazani
- Department of Food Science, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
| | - Alejandro Marnangoni
- Department of Food Science, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
| | - Michael A Rogers
- Department of Food Science, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
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