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Polymer Classification: Architecture

Polymer Classification: Architecture

Polymers are classified as linear or branched on the basis of their chain architecture. The polymer chains in linear polymers have a long chain-like structure with minimal to no branching at all. Even if a polymer features large substituent groups on the monomer, which appear as branches to the skeleton, it is not considered a branched polymer. A branched polymer contains secondary polymer chains that arise from the main polymer chain. The branching occurs when the polymer growth shifts from...

Cationic Chain-Growth Polymerization: Mechanism

Cationic Chain-Growth Polymerization: Mechanism

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 generated carbocation,...

Anionic Chain-Growth Polymerization: Mechanism

Anionic Chain-Growth Polymerization: Mechanism

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 acceptor.

Anionic Chain-Growth Polymerization: Overview

Anionic Chain-Growth Polymerization: Overview

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,...

Ion Exchange

Ion Exchange

Ion exchange chromatography separates charged molecules from a solution by reversibly exchanging them with mobile, or 'active', ions associated with the oppositely charged stationary phase. This method can be used to separate ions, soften and deionize water, and purify solutions. The polymers comprising the ion-exchange column are high-molecular-weight and chemically stable polymers, crosslinked to be porous and essentially insoluble. They are also functionalized with either acidic or basic...

Step-Growth Polymerization: Overview

Step-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...

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Related Experiment Video

Updated: Jun 23, 2026

Synthesis of Soft Polysiloxane-urea Elastomers for Intraocular Lens Application

Synthesis of Soft Polysiloxane-urea Elastomers for Intraocular Lens Application

Published on: March 8, 2019

High solid and high stability waterborne polyurethanes via ionic groups in soft segments and chain termini.

S K Lee¹, B K Kim

¹Department of Polymer Science and Engineering, Pusan National University, Busan 609-735, Republic of Korea.

Journal of Colloid and Interface Science

|May 8, 2009

Summary

Molecularly designing waterborne polyurethanes with ionic groups at chain ends yields highly stable, high-solid dispersions. This strategy enhances dispersion properties without compromising mechanical performance.

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Microwave-assisted Functionalization of Poly(ethylene glycol) and On-resin Peptides for Use in Chain Polymerizations and Hydrogel Formation

Microwave-assisted Functionalization of Poly(ethylene glycol) and On-resin Peptides for Use in Chain Polymerizations and Hydrogel Formation

Published on: October 29, 2013

Area of Science:

Polymer Chemistry
Materials Science
Surface Chemistry

Background:

Waterborne polyurethanes (WPUs) are crucial for environmentally friendly coatings and adhesives.
Achieving high solid content and stability in WPUs remains a significant challenge.
Controlling ionic group placement is key to tailoring WPU properties.

Purpose of the Study:

To investigate the impact of anionic group positioning on the properties of high solid waterborne polyurethanes.
To synthesize and characterize WPUs with varying ionic group locations and polyol molecular weights.
To establish a molecular design strategy for enhanced WPU dispersion stability and performance.

Main Methods:

Molecular design and synthesis of waterborne polyurethanes.
Systematic variation of anionic group positions (terminal vs. hard segment) and concentrations.
Characterization of dispersion particle size, stability, viscosity, and water swelling.
Evaluation of mechanical and dynamic mechanical properties of cast films.

Main Results:

Terminal ionic groups resulted in the smallest particle size, highest stability, and viscosity.
Hard segment ionic groups led to the greatest water swelling.
Dispersion cast films exhibited similar mechanical and dynamic mechanical properties regardless of ionic group placement.
Highly stable dispersions (45% solid content) were achieved with low ionic content (2%) by placing ions at chain ends.

Conclusions:

Incorporating ionic groups at the flexible chain ends is an effective strategy for creating highly stable, high-solid WPUs.
The enhanced dispersion properties are attributed to the high mobility and low free energy of terminal ionic groups.
This molecular design approach offers a pathway to advanced, sustainable polyurethane materials.