Related Experiment Video
Updated: Nov 21, 2025
08:50
Stabilizing Hepatocellular Phenotype Using Optimized Synthetic Surfaces
Published on: September 26, 2014
10.4K
Controlled Synthesis of Polyphosphazenes with Chain-Capping Agents
Krzysztof Matyjaszewski1, Robert A Montague1
1Department of Chemistry, Carnegie Mellon University, 4400 Fifth Avenue, Pittsburgh, PA 15213, USA.
Molecules (Basel, Switzerland)
|January 13, 2021
Summary
Four novel N-alkyl phosphoranimines were synthesized and tested as chain-capping agents in anionic polymerization. These compounds effectively controlled polyphosphazene molecular weights, with chain transfer constants determined.
Area of Science:
- Polymer Chemistry
- Organophosphorus Chemistry
Background:
- Phosphoranimines are versatile compounds with applications in polymer synthesis.
- Controlling molecular weight is crucial for tailoring polymer properties.
Purpose of the Study:
- To synthesize and characterize novel N-alkyl phosphoranimines.
- To evaluate their efficacy as chain-capping agents in anionic polymerization.
- To determine chain transfer constants for improved control over polymer architecture.
Main Methods:
- Synthesis of N-alkyl phosphoranimines via the Staudinger reaction.
- Anionic polymerization of a phosphoranimine monomer.
- Characterization using 1H-NMR spectroscopy.
- Determination of chain transfer constants using the Mayo equation.
Main Results:
- Four N-alkyl phosphoranimines (N-adamantyl, N-benzyl, N-t-butyl, N-trityl) were successfully synthesized.
- These compounds acted as effective chain-capping agents in bulk polymerization.
- Controlled molecular weights of resulting polyphosphazenes were achieved.
- Chain transfer constants were determined for the monomer and N-benzyl phosphoranimine.
Conclusions:
- N-alkyl phosphoranimines are effective chain-capping agents for controlling polyphosphazene molecular weight.
- The Staudinger reaction provides a viable route for synthesizing these functional monomers.
- Further studies can explore a wider range of alkyl groups and polymerization conditions.
Related Concept Videos
00:57Cationic Chain-Growth Polymerization: Mechanism
2.6K
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...
2.6K
01:17Ziegler–Natta Chain-Growth Polymerization: Overview
3.7K
Ziegler–Natta polymerization is another form of addition or chain‐growth polymerization used for synthesizing linear polymers over branched polymers. The catalyst used for polymerization is the Ziegler–Natta catalyst, named after Karl Ziegler and Giulio Natta, who developed it in 1953. This catalyst is an organometallic complex of titanium tetrachloride and triethyl aluminum, with the active form of the catalyst being an alkyl titanium compound. Using the Ziegler–Natta...
3.7K
01:16Olefin Metathesis Polymerization: Ring-Opening Metathesis Polymerization (ROMP)
2.9K
Ring-opening metathesis polymerization or ROMP involves strained cycloalkenes as starting materials. The mechanism of ROMP proceeds by reacting cycloalkene with Grubbs catalyst to give metallacyclobutane intermediate which undergoes a ring-opening reaction to form new carbene. The new carbene reacts with another molecule of cycloalkene. Repetition of these steps leads to the formation of an unsaturated open-chain polymer product. All these steps are reversible, however, relieving the ring...
2.9K
01:20Anionic Chain-Growth Polymerization: Overview
2.3K
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,...
2.3K
01:03Step-Growth Polymerization: Overview
4.1K
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...
4.1K
02:34Polymers
39.4K
The word polymer is derived from the Greek words “poly” which means “many” and “mer” which means “parts”. Polymers are long chains of molecules composed of repeating units of smaller molecules, known as monomers. They either occur naturally, such as DNA and proteins, or can be constructed synthetically, like plastics. They have varied structural characteristics, such as linear chains, branched chains, or complex networks, that contribute to the...
39.4K