Related Experiment Video
Updated: Oct 27, 2025
15:33
Microwave-assisted Functionalization of Polyethylene glycol and On-resin Peptides for Use in Chain Polymerizations and Hydrogel Formation
Published on: October 29, 2013
29.3K
Chain-End Effects on Supramolecular Poly(ethylene glycol) Polymers
Ana Brás1, Ana Arizaga1, Uxue Agirre1
1Institute of Physical Chemistry, University of Cologne, 50939 Cologne, Germany.
Polymers
|July 24, 2021
Summary
This study analyzes how different hydrogen bonding groups in modified poly(ethylene glycol) (PEG) affect its structure and dynamics. Changing the H-bonding type significantly alters PEG
Area of Science:
- Polymer Science
- Materials Science
- Supramolecular Chemistry
Background:
- Poly(ethylene glycol) (PEG) is a versatile polymer whose properties can be tuned by end-functionalization.
- Hydrogen bonding (H-bonding) interactions offer a route to modify polymer structure and dynamics through supramolecular assembly.
- Understanding the influence of specific H-bonding groups is crucial for designing advanced polymer materials.
Purpose of the Study:
- To investigate the role of different hydrogen bonding (H-bonding) types on the bulk structure and dynamics of chain-end modified poly(ethylene glycol) (PEG).
- To correlate changes in H-bonding chemistry with macroscopic properties like viscosity and viscoelasticity.
- To explore how varying the Flory-Huggins interaction parameter influences supramolecular behavior in PEG.
Main Methods:
- Small-angle scattering (SAS) for structural analysis.
- Linear rheology and differential scanning calorimetry (DSC) for probing dynamics and thermal transitions.
- Percus-Yevick approximation to model inter-particle structure factors for specific H-bonding groups.
Main Results:
- PEG functionalized with thymine-1-acetic acid (thy) and diamino-triazine (dat) exhibited linear block copolymer structures and Newtonian-like dynamics.
- PEG functionalized with 2-ureido-4[1H]-pyrimidinone (upy) showed spherical cluster formation and network-like dynamics, including shear thickening behavior.
- The Flory-Huggins interaction parameter increased from PEG-thy/dat to PEG-upy, correlating with distinct structural and dynamic properties.
Conclusions:
- The type of H-bonding group profoundly impacts the supramolecular organization and dynamics of modified PEG.
- Up to 300 characters. PEG-upy's network-like behavior and shear thickening are linked to cluster formation and dissociation dynamics.
- Tailoring H-bonding associations provides a powerful strategy to control PEG properties for potential applications.
Related Concept Videos
01:04Anionic Chain-Growth Polymerization: Mechanism
2.2K
The mechanism for anionic chain-growth polymerization involves initiation, propagation, and termination steps. In the initiation step, a nucleophilic anion, such as butyl lithium, initiates the polymerization process by attacking the π bond of the vinylic monomer. As a result, a carbanion, stabilized by the electron‐withdrawing group, is generated. The resulting carbanion acts as a Michael donor in the propagation step and attacks the second vinylic monomer, which acts as a Michael...
2.2K
01:03Step-Growth Polymerization: Overview
3.9K
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...
3.9K
02:35Free-Radical Chain Reaction and Polymerization of Alkenes
8.6K
The conversion of alkenes to macromolecules called polymers is a reaction of high commercial importance. The structure of the polymer is defined by a repeating unit, while the terminal groups are considered insignificant. The average degree of polymerization represents the number of repeating units in the polymer molecule and is denoted by the subscript n.
8.6K
01:20Anionic Chain-Growth Polymerization: Overview
2.2K
The polymerization process that involves carbanion as an intermediate is called anionic polymerization. It is also a type of addition or chain-growth polymerization. Anionic polymerization gets initiated by a strong nucleophile such as an organolithium or a Grignard reagent. The most commonly used initiator for anionic polymerization is butyl lithium. Monomers involved in anionic polymerization must possess a vinyl group bonded to one or two electron-withdrawing groups. For instance,...
2.2K
00:57Cationic Chain-Growth Polymerization: Mechanism
2.5K
The cationic polymerization mechanism consists of three steps: initiation, propagation, and termination. In the initiation step of the polymerization process, the π bond of a monomer gets protonated by the Lewis acid catalyst, which is formed from boron trifluoride and water. The protonation of the π bond generates a carbocation stabilized by the electron‐donating group. In the propagation step, the π bond of the second monomer acts as a nucleophile and attacks the...
2.5K
01:17Radical Chain-Growth Polymerization: Chain Branching
2.1K
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...
2.1K