Name: self-assembling morphologies obtained from helical polycarbodiimide copolymers and their triazole derivatives
Uploaded: 2017-02-07T13:00:00
Description: Watch this Scientific Journal Video about Self-assembling Morphologies Obtained from Helical Polycarbodiimide Copolymers and Their Triazole Derivatives at JoVE.com

We gratefully acknowledge the NSF-MRI grant (CHE-1126177) used to purchase the Bruker Advance III 500 NMR instrument.

NOTE: All reactions were performed in a glove box (or fume hood, when noted) using standard scintillation vials.
1. Synthesis of the (R)- and (S)-series of Ethynylpolycarbodiimides
<ol>
	<li>Place 1.0 g (0.00442 mol) of N-(3-ethynylphenyl)-N&#39;-hexylcarbodiimide monomer (ET) and 0.894 g (0.00442 mol) of N-phenyl-N&#39;-hexylcarbodiimide monomer (Ph) as transparent, viscous liquids in a clean scintillation vial (20 mL) with ...

<ol>
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In summary, the spin-coating deposition method represents a convenient way to reproducibly generate multiple-type morphologies, including fiber-like aggregates, ribbons, worm-like structures, fibrillar networks, looped fibers, toroids, and superhelices, from either alkyne polycarbodiimides or from their respective PS-derivatives (i.e., polycarbodiimide-g-polystyrenes). Thus, coordination-insertion polymerization, along with further functionalization using a &#34;click&#34; reaction followed by ATRP, pro...

The helix is a ubiquitous chiral motif observed in nature. Complex biological systems and their components, such as proteins, polypeptides, and DNA, all utilize the helical structure as a means of performing complex tasks for applications like information storage, tissue molecular transportation support, and localized chemical transformations.
Helical polymeric macromolecules1 have been a target for the design of functional materials and composites possessing interesting properties, which enabled their practical use in many areas2,3,4,5. So far, numerous helical scaffolds6,7,8,9, as well as their secondary structure motifs, have been successfully exploited to achieve promising results, both in the field of physical engineering10,11,12 and in biological applications13,14. Current studies represent a logical extension of our earlier efforts to synthesize optically active alkyne polycarbodiimides bearing one or two modifiable alkyne moieties per repeat unit15,16,17.
Recently, we reported22 the homo- and co-polymerization of carbodiimide monomers leading to chiral helical macromolecules &#8212; a family of (R)- and (S)-polycarbodiimides with modifiable pendant groups that offer further functionalization through a CuAAC &#34;click&#34; protocol. Br-terminated polycarbodiimides obtained from their respective ethynyl precursors were shown to act as ATRP macroinitiators in graft-polymerization with styrene23.
The specific aim of this manuscript is to provide a practical guide for morphological characterizations (AFM measurements and SEM inspection) of the secondary structures formed from PS-PCDs synthesized from their corresponding ethynyl precursors by using a well-known click protocol21. In particular, experimental details, such as the solvent of choice, the temperature, the deposition method, the substrate chosen for deposition, and the polymer structure, were shown to be highly important to obtain specific morphologies (e.g., fibers, including right- and left-handed helical senses; nano-spheres; and nano-rings). They may also be of use for the development of materials with tunable properties based on polycarbodiimides with precisely controlled chiral architecture.

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		<tr height="42">
			<td height="42" style="height:42px;width:216px;">styrene</td>
			<td style="width:71px;">Sigma-Aldrich</td>
			<td style="width:119px;">S4972-1L</td>
			<td style="width:167px;">reagent</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">N,N,N&#8242;,N&#8242;&#8242;,N&#8242;&#8242;- Pentamethyldiethylenetriamine (PMDETA)</td>
			<td style="width:71px;">Sigma-Aldrich</td>
			<td>369497-250ML</td>
			<td>reagent</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Copper(I) iodide</td>
			<td style="width:71px;">Sigma-Aldrich</td>
			<td style="width:119px;">215554-5G</td>
			<td>reagent</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Copper(I) chloride</td>
			<td style="width:71px;">Alfa-Aesar</td>
			<td style="width:119px;">14644, 5G</td>
			<td>reagent</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU)</td>
			<td style="width:71px;">Sigma-Aldrich</td>
			<td style="width:119px;">139009-100G</td>
			<td>reagent</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">N,N-dimethylformamide (DMF)</td>
			<td style="width:71px;">Sigma-Aldrich</td>
			<td style="width:119px;">227056-100mL</td>
			<td>solvent</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Tetrahydrofuran (THF)</td>
			<td style="width:71px;">Acros-Organics</td>
			<td style="width:119px;">B0320346</td>
			<td>solvent</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Chloroform</td>
			<td style="width:71px;">Sigma-Aldrich</td>
			<td style="width:119px;">372978-100mL</td>
			<td>solvent</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Methanol</td>
			<td style="width:71px;">Fisher-Chemical</td>
			<td style="width:119px;">A411-20</td>
			<td>solvent</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">20 mL glass scintillation vials</td>
			<td style="width:71px;">Cole-Palmer</td>
			<td style="width:119px;">UX-08918-03</td>
			<td>glassware</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">1-Dram vials (15 x 45 mm)</td>
			<td style="width:71px;">Kimble-Chase</td>
			<td style="width:119px;">KIM-60965D-1</td>
			<td>glassware</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">13 mm syringe filter with 0.45&#181;m PTFE membrane</td>
			<td style="width:71px;">VWR International</td>
			<td style="width:119px;">28145-493</td>
			<td>membrane filter</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Silicon wafer disks (25.4&#177; .5 mm)</td>
			<td style="width:71px;">Wafer World, Inc</td>
			<td style="width:119px;">S076453</td>
			<td>AFM substrate</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Corning Stirrer/Hot Plate</td>
			<td style="width:71px;">Hot Plate</td>
			<td style="width:119px;">PC-420</td>
			<td>heating device</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">single stage Unilab mBraun glove box</td>
			<td style="width:71px;">Unilab</td>
			<td style="width:119px;">12-109</td>
			<td>glove box</td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Nanoscope IV-Multimode Veeco AFM-machine</td>
			<td style="width:71px;">Veeco</td>
			<td style="width:119px;">3100 Dimension V Atomic Probe Microscope</td>
			<td>AFM-instrument</td>
		</tr>
	</tbody>
</table>

self-assembling morphologies obtained from helical polycarbodiimide copolymers and their triazole derivatives

A facile method for the preparation of polycarbodiimide-based secondary structures (e.g., nano-rings, &#34;craters,&#34; fibers, looped fibers, fibrous networks, ribbons, worm-like aggregates, toroidal structures, and spherical particles) is described. These aggregates are morphologically influenced by extensive hydrophobic side chain-side chain interactions of the singular polycarbodiimide strands, as inferred by atomic force microscopy (AFM) and scanning electron microscopy (SEM) techniques. Polycarbodiimide-g-polystyrene copolymers (PS-PCDs) were prepared by a combination of synthetic methods, including coordination-insertion polymerization, copper(I)-catalyzed azide alkyne cycloaddition (CuAAC) &#34;click&#34; chemistry, and atom transfer radical polymerization (ATRP). PS-PCDs were found to form specific toroidal architectures at low concentrations in CHCl3. To determine the influence of a more polar solvent medium (i.e., THF and THF/EtOH) on polymer aggregation behavior, a number of representative PS-PCD composites have been tested to show discrete concentration-dependent spherical particles. These fundamental studies are of practical interest to the development of experimental procedures for desirable architectures by directed self-assembly in thin film. These architectures may be exploited as drug carriers, whereas other morphological findings represent certain interest in the area of novel functional materials.

Figure 1 (upper panel) illustrates BINOL (R)- or (S)-titanium (IV) catalyst-mediated coordination-insertion polymerization leading to the (R)- and (S)-series of ethynylpolycarbodiimides with an altering ratio of the repeat units (i.e., aryl- and alkyne aryl). Monomers and catalysts were obtained as described elsewhere18. Both (R)- and (S)-family alkyne random copolymers were selected fo...

Watch this Scientific Journal Video about Self-assembling Morphologies Obtained from Helical Polycarbodiimide Copolymers and Their Triazole Derivatives at JoVE.com

Self-assembling Morphologies Obtained from Helical Polycarbodiimide Copolymers and Their Triazole Derivatives

Here, we present a protocol to prepare and visualize secondary structures (e.g., fibers, toroidal architectures, and nano-spheres) derived from helical polycarbodiimides. The morphology characterized by both atomic force microscopy (AFM) and scanning electron microscopy (SEM) was shown to depend on molecular structure, concentration, and the solvent of choice.

A facile method for the preparation of polycarbodiimide-based secondary structures (e.g., nano-rings, &#34;craters,&#34; fibers, looped fibers, fibrous ...

The overall goal of this protocol is to demonstrate a rational synthetic approach to helical polycarbodiimides bearing modifiable pendant groups and visualize the secondary structures assembled from them by means of atomic force microscopy. These studies are of particular interest to develop experimental procedures for the preparation of desirable architectures. These architectures may then be exploited as potential sensors, optical switches, or biomedical applications.The main advantage of this technique is that it can be easily applied to different polycarbodiimide scaffolds to make specific assemblies, such as donuts, ribbons, fibers, superhelices, spheres, and so on. The implication of this technique extends towards using helical polycarbodiimide scaffold as potential drug carriers. Because this party-like micromolecules self assemble into unique architecture in a controllable fashion.To begin this procedure, add one gram of ET monomer and 0.894 grams of pH monomer to a clean 20-milliliter scintillation vial containing a magnetic stir bar in a glove box. Then, add 0.018 grams of BINOL catalyst to the scintillation vial. Add approximately three to five milliliters of anhydrous chloroform and gently stir to dissolve both the monomer and the catalyst.After capping the vial, allow the reaction mixture to stir overnight at 25 degrees Celsius. Redissolve the polymer in five to ten milliliters of chloroform and reprecipitate it in 250 milliliters of methanol to remove the residual catalyst. Then, dry the precipitant under high vacuum for 24 hours to remove the methanol.In the glove box, add five milliliters of anhydrous THF and a magnetic stir bar to a scintillation vial containing 0.25 grams of R 50 ethynol 50 phenol composition. Then, add 0.146 grams of the desired amide to the scintillation vial. Following this, add 0.022 grams of copper iodide catalyst to the scintillation vial.Allow the solution to stir for two minutes to form a homogeneous suspension. Now, add 0.713 grams of DBU to the homogeneous suspension and allow it to stir for two hours at 25 degrees Celsius. Cyclic reaction must be conducted for two hours.Long reaction time should be avoided to prevent hard gel formation, such as insoluble inemulsive organic solvents. After removing the vial from the glove box, remove the magnetic stir bar and inject the greenish, gel-like solution into 250 milliliters of cold methanol, containing 0.5 milliliters of DBU. Collect the formed triazole polymer by filtration using a 15-milliliter fritted funnel, and wash it once with 250 milliliters of methanol.After repeating the purification, dry the product of the click reaction under high vacuum for 24 hours to remove the methanol. In the glove box, mix 0.029 grams of copper chloride catalyst with 0.1 grams of the macro-initiator in a scintillation vial containing 0.101 grams of PMDETA. After adding a magnetic stir bar to the vial, add 1.51 grams of freshly distilled styrene.Then, add approximately 12 milliliters of anhydrous toluene to dissolve the reagents. Once the vial has been sealed and removed from the glove box immerse it in an oil bath and increase the tempurature. Stir the reaction mixture at the desired tempurature for 12 hours in a fume hood.After removing the magnetic stir bar, pour the reaction mixture into 250 milliliters of cold methanol, containing 0.5 milliliters of DBU. Then, collect the formed flakes by filtration, using a 15-milliliter fritted funnel, and wash the material once with approximately 50 milliliters of cold methanol. Filter each polymeric stock solution through a 0.45 micrometer PTFV syringe filter prior to deposition on a silicon wafer.Immediately after depositing 200 microliters of sample on the silicon wafer, use a spin coating machine to cover the entire wafer surface with a uniform polymeric film for AFM measurements. BINAL R or S titanium catalyst-mediated coordination insertion polymerization leading to the R and S series of polycarbodiimides is shown here. The synthesis of the triazole polycarbodiimides used as macro-initiators in the ATRP reaction to produce polycarbodiimide-g-polystyrenes, or PSPCDs is displayed here.Macromolecules can self-assemble in a thin film to form a variety of complex super-molecular architectures, such as fibers, looped fibers, superhelices, fibrous networks, ribbons, worm-like aggregates, toroidal structures, and craters. A molecular model of the triazole macro-initiator is shown here. AFM images of alkyne PCDs confirm the formation of fiber-like morphologies.In general, diluting stock solutions resulted in diminishing the size of the aggregated morphologies formed. The morphologies formed from PSPCDs, spin coated from chloroform stock are shown here. Unlike alkyne polycarbodiimide aggregation behaviors in chloroform, examining PSPCDs revealed both crater-like assemblies and nano-sized choroidal architectures as predominate motifs.AFM images of PSPCDs indicative of the formation of discrete nanospheres when applying a single or binary solvent system for sample deposition, with concentration-dependent particle sizes are shown here. The assembly of the individual macromolecules into spherical nanoparticles matching up closely with SEM-measured morphologies is displayed here. Remarkably, the greater micron-size aggregates may be compromised of individual nanoparticles agglomerated together.The spin-coating method represents a convenient way to reproducibly make multiple type morphologies, including fibers, superhelices, donut-like architectures, microspheres, based on ethynol polycarbodiimides and their respective polystyrene derivatives. While preparing polycarbodiimide films on silicon wafers it should be air dried for a few hours for AMF imaging. This time we'll facilitate these macromolecules to self-organizing to specific identifiable morphologies.And as an important practical finding of the studies is that the formation of secondary structures is strongly influenced by concentration and the solvent. Following this procedure, other methods, such as TEM, SEM, and XRD can be performed. This allows us to ask additional questions related to the structure of helical polycarbodiimides.Our goal is to develop materials with precisely controlled kyro-architectures and tunable properties. Future applications of this method, with respect to polycarbodiimides, may include the development of kyro sensors or constructing spherical aggregates as carriers for drug delivery. In addition, we can design novel molecular scaffolds that possess defined microstructures displaying interesting kyro-optical switching properties

Research

JoVE Journal

Chemistry

Synthesis of Antiviral Tetrahydrocarbazole Derivatives by Photochemical and Acid-catalyzed C-H Functionalization via Intermediate Peroxides (CHIPS)

Synthesis of Antiviral Tetrahydrocarbazole Derivatives by Photochemical and Acid-catalyzed C-H Functionalization via Intermediate Peroxides CHIPS

The direct functionalization of C-H bonds is an important and long standing goal in organic chemistry. Such transformations can be very powerful in order ...

Synthesis of Non-uniformly Pr-doped SrTiO3 Ceramics and Their Thermoelectric Properties

Synthesis of Non-uniformly Pr-doped SrTiO3 Ceramics and Their Thermoelectric Properties

We demonstrate a novel synthesis strategy for the preparation of Pr-doped SrTiO3 ceramics via a combination of solid state reaction and spark plasma ...

Facile Preparation of 4-Substituted Quinazoline Derivatives

Reported in this paper is a very simple method for direct preparation of 4-substituted quinazoline derivatives from a reaction between substituted ...

Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives

Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives

Molecules bearing trifluoromethoxy (OCF3) group often show desired pharmacological and biological properties. However, facile synthesis of ...

Functionalization of Single-walled Carbon Nanotubes with Thermo-reversible Block Copolymers and Characterization by Small-angle Neutron Scattering

We demonstrate a protocol for single-walled carbon nanotube functionalization using thermo-sensitive PEO-PPO-PEO triblock copolymers in an aqueous ...

Combustion Chemistry of Fuels: Quantitative Speciation Data Obtained from an Atmospheric High-temperature Flow Reactor with Coupled Molecular-beam Mass Spectrometer

This manuscript describes a high-temperature flow reactor experiment coupled to the powerful molecular beam mass spectrometry (MBMS) technique. This ...

Constructing Thioether/Vinyl Sulfide-tethered Helical Peptides Via Photo-induced Thiol-ene/yne Hydrothiolation

Here, we describe a detailed protocol for the preparation of thioether-tethered peptides using on-resin intramolecular/intermolecular thiol-ene ...

Facile Protocol for the Synthesis of Self-assembling Polyamine-based Peptide Amphiphiles (PPAs) and Related Biomaterials

Facile Protocol for the Synthesis of Self-assembling Polyamine-based Peptide Amphiphiles PPAs and Related Biomaterials

Polyamine-based Peptide Amphiphiles (PPAs) are a new class of self-assembling amphiphilic biomaterials-related to the peptide amphiphiles (PAs). ...

Synthesis and Characterization of 1,2-Dithiolane Modified Self-Assembling Peptides

This report focuses on the synthesis of an N-terminus 1,2-dithiolane modified self-assembling peptide and the characterization of the resulting ...

Methionine Functionalized Biocompatible Block Copolymers for Targeted Plasmid DNA Delivery

Reversible addition-fragmentation chain transfer (RAFT) polymerization integrates the advantages of radical polymerization and living polymerization. This ...