Related Experiment Video
Updated: Jul 5, 2026
09:22
Self-assembling Morphologies Obtained from Helical Polycarbodiimide Copolymers and Their Triazole Derivatives
Published on: February 7, 2017
Consecutive conformational transitions and deaggregation of multiple-helical poly(diacetylene)s
Jan Weiss1, Eike Jahnke, Nikolai Severin
1Department of Materials, ETH Zürich, Zürich, Switzerland.
Nano Letters
|May 9, 2008
Summary
Oligopeptide-polymer conjugates form helical conjugated polymers that dynamically fold. These self-assembling materials show transitions similar to biopolymers, paving the way for biofunctional optoelectronic materials.
Area of Science:
- Polymer chemistry
- Supramolecular chemistry
- Biomaterials science
Background:
- Diacetylene macromonomers based on oligopeptide-polymer conjugates can polymerize.
- These polymers form complex multiple-helical quaternary structures.
- The dynamic folding behavior of these structures is not fully understood.
Purpose of the Study:
- To investigate the conformational transitions of multiple-helical conjugated polymers.
- To explore the role of protic cosolvents in polymer folding.
- To assess the potential of these polymers as biofunctional materials.
Main Methods:
- Polymerization of diacetylene macromonomers.
- Addition of protic cosolvents to induce conformational changes.
- Observation of helix-helix and helix-coil transitions.
- Analysis of aggregation state changes in superstructures.
Main Results:
- Conjugated polymers with multiple-helical quaternary structures were successfully synthesized.
- Addition of protic cosolvents induced dynamic folding behavior.
- A helix-helix transition with helix-sense inversion was observed, followed by a reversible helix-coil transition.
- These transitions were linked to changes in the aggregation state of the polymer superstructures.
Conclusions:
- The synthesized polymers exhibit complex, cooperative conformational transitions.
- The observed transitions resemble those of natural biopolymers.
- Supramolecular self-assembly is a viable strategy for creating biofunctional materials with optoelectronic properties.
Related Concept Videos
01:28Stability of Conjugated Dienes
Introduction
A comparison of the enthalpies of hydrogenation of dienes reveals that conjugated dienes release less heat on hydrogenation, rendering them more stable than their nonconjugated analogs.
A comparison of the enthalpies of hydrogenation of dienes reveals that conjugated dienes release less heat on hydrogenation, rendering them more stable than their nonconjugated analogs.
00:52¹H NMR of Conformationally Flexible Molecules: Temporal Resolution
At room temperature, the chair conformer of cyclohexane undergoes rapid ring flipping between two equivalent chair conformers at a rate of approximately 105 times per second. These two chair conformers are in equilibrium. The rapid ring flipping results in the interconversion of the axial proton to an equatorial proton and an equatorial to the axial proton. Such interconversions are too rapid and cannot be detected on the NMR timescale. Hence, the NMR spectrometer cannot distinguish between the...
02:02Chair Conformation of Cyclohexane
The chair conformation is the most stable form of cyclohexane due to the absence of angle and torsional strain. The absence of angle strain is a result of cyclohexane’s bond angle being very close to the ideal tetrahedral bond angle of 109.5° in its chair conformer. Similarly, the torsional strain is also absent owing to the perfectly staggered arrangement of bonds.
The hydrogen atoms linked to carbons are arranged in two different axial and equatorial orientations to achieve this staggered...
The hydrogen atoms linked to carbons are arranged in two different axial and equatorial orientations to achieve this staggered...
01:17Radical Chain-Growth Polymerization: Chain Branching
The skeletal structure of polymers synthesized via radical polymerization is always branched. For example, the polymerization of ethylene by radical polymerization results in a low-density grade of polyethylene with a heavily branched skeletal structure. Here, the radical site abstracts hydrogen from the growing chain, and the radical site shifts from the end (a primary carbon center) to anywhere within the growing chain (a secondary carbon center). Consequently, the part of the chain from the...
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
01:03Step-Growth Polymerization: Overview
Step-growth or condensation polymerization is a stepwise reaction of bi or multifunctional monomers to form long-chain polymers. As all the monomers are reactive, most of the monomers are consumed at the early stages of the reaction to form small chains of reactive oligomers, which then combine to form long polymer chains in the late stages. Hence, the reaction has to proceed for a long time to achieve high molecular weight polymers.
Many natural and synthetic polymers are produced by...
Many natural and synthetic polymers are produced by...