Related Experiment Video
Updated: Aug 7, 2025
08:44
Assembly and Characterization of Polyelectrolyte Complex Micelles
Published on: March 2, 2020
10.9K
Strong Variation of Micelle-Unimer Coexistence as a Function of Core Chain Mobility
Ryan J Carrazzone1, Xiuli Li1, Jeffrey C Foster1
1† Department of Chemistry and Macromolecules Innovation Institute, Virginia Tech, Blacksburg, VA, 24061, United States.
Macromolecules
|March 13, 2023
Summary
The mobility of polymer chains within micelle cores significantly impacts self-assembly. Lowering the glass transition temperature (Tg) of core blocks increases the concentration of free polymer chains (unimers) in solution.
Area of Science:
- Polymer Chemistry
- Materials Science
- Physical Chemistry
Background:
- Polymeric micelles are self-assembled structures formed by amphiphilic block copolymers in solution.
- These micelles often coexist with individual polymer chains, known as unimers.
- Understanding the factors governing this coexistence is crucial for applications like drug delivery.
Purpose of the Study:
- To investigate the effect of core-forming block's glass transition temperature (Tg) on micelle-unimer coexistence.
- To determine how chain mobility within the micelle core influences self-assembly behavior.
- To provide insights for designing stable polymeric nanostructures.
Main Methods:
- Synthesis of poly(ethylene glycol)-block-poly(n-butyl acrylate-ran-tert-butyl acrylate) [PEG-b-P(nBA-ran-tBA)] copolymers.
- Modulation of the P(nBA-ran-tBA) core block's Tg by varying the nBA/tBA molar ratio.
- Nuclear Magnetic Resonance (NMR) diffusometry to quantify unimer populations.
Main Results:
- A series of copolymers with similar molecular weights and micelle sizes were synthesized.
- Decreasing the core block Tg from 25 °C to -46 °C led to an increase in unimer population from 0% to 54%.
- Unimer population increased with temperature at a fixed polymer composition and core Tg.
Conclusions:
- Core-forming block chain mobility (Tg) strongly influences polymer self-assembly and micelle-unimer equilibrium.
- This finding is critical for the rational design of drug delivery systems and other nanotechnologies.
- The results highlight the need for advanced dynamical theories to fully describe polymer self-assembly phenomena.
Related Concept Videos
01:26Membrane Fluidity
11.4K
Membrane fluidity is explained by the fluid mosaic model of the cell membrane, which describes the plasma membrane structure as a mosaic of components—including phospholipids, cholesterol, proteins, and carbohydrates—that gives the membrane a fluid character.
Mosaic nature of the membrane
The mosaic characteristic of the membrane helps the plasma membrane remain fluid. The integral proteins and lipids exist as separate but loosely-attached molecules in the membrane. The membrane is...
Mosaic nature of the membrane
The mosaic characteristic of the membrane helps the plasma membrane remain fluid. The integral proteins and lipids exist as separate but loosely-attached molecules in the membrane. The membrane is...
11.4K
03:22Colloids
17.7K
Children at play often make suspensions such as mixtures of mud and water, flour and water, or a suspension of solid pigments in water known as tempera paint. These suspensions are heterogeneous mixtures composed of relatively large particles that are visible to the naked eye or can be seen with a magnifying glass. They are cloudy, and the suspended particles settle out after mixing. On the other hand, a solution is a homogeneous mixture in which no settling occurs and in which the dissolved...
17.7K
00:59Mechanisms of Membrane Domain Formation
3.1K
Different physical properties of lipids and proteins allow them to localize and form distinct islands or domains in the membrane. Some membrane domains are formed due to protein-protein interactions, whereas others are formed due to the presence of specific lipids such as sphingolipids and sterols—for example, large proteins, such as bacteriorhodopsin, aggregate and create distinct domains.
Another mechanism for membrane domain formation involves membrane proteins interacting with...
Another mechanism for membrane domain formation involves membrane proteins interacting with...
3.1K
01:35Asymmetric Lipid Bilayer
7.3K
Biological membranes show uneven distribution of different types of lipids in the inner and outer layers, resulting in transverse asymmetric membranes. The treatment of the erythrocyte membrane with the enzyme phospholipase confirmed the asymmetric nature of the lipid bilayer. The enzyme hydrolyzes lipids into fatty acids and hydrophilic groups. The phospholipase acts only on the outer layer of the membrane, while the inner layer remains intact. The phospholipase treatment resulted in 80%...
7.3K
01:32Lipids as Anchors
5.7K
In the plasma membrane, the lipids forming the bilayer can also act as an anchor to tether proteins to the membrane. The three main types of lipid anchors found in eukaryotes are – prenyl groups, fatty acyl groups, and glycosylphosphatidylinositol or GPI groups. Prenyl and fatty acyl groups act as anchors on the cytosolic surface of the membrane, whereas GPI anchors proteins on the extracellular side.
The carboxy-terminal of most of the prenylated proteins, such as Ras proteins, contains...
The carboxy-terminal of most of the prenylated proteins, such as Ras proteins, contains...
5.7K
00:57Cationic Chain-Growth Polymerization: Mechanism
2.4K
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...
2.4K