What Is 4,4′-Oxydianiline (ODA, CAS 101-80-4)? Properties and Applications

4,4′-Oxydianiline, commonly abbreviated as 4,4′-ODA or ODA, is an aromatic diamine identified by CAS 101-80-4. It is also known as 4,4′-diaminodiphenyl ether or bis(4-aminophenyl) ether. The compound contains two aromatic rings connected through an ether linkage, with an amino group positioned at the para position of each ring.

This molecular architecture is the main reason 4,4′-ODA is associated with high-performance polymer chemistry. Its two amino groups provide reactive sites used in polymer-forming systems, while the aromatic backbone contributes rigidity and thermal stability to the resulting molecular structure. The ether linkage between the aromatic rings introduces a degree of rotational flexibility compared with structures built from directly bonded rigid aromatic units.

For this reason, 4,4′-ODA is widely associated with polyimide chemistry and other heat-resistant polymer systems. Its relevance is not based on a single physical property. It comes from the combination of aromatic character, diamine functionality and the ether bridge within the same molecule.

The product information currently published by Starsky Chemical identifies 4,4′-Oxydianiline as CAS 101-80-4 with a molecular formula of C12H12N2O and a molecular weight of 200.24 g/mol. The company also lists applications associated with polyimides and several related high-temperature polymer materials.

What Is 4,4′-Oxydianiline?

From a chemical classification perspective, 4,4′-Oxydianiline is an aromatic diamine.

Its molecular structure can be considered in three functional parts:

• · two benzene rings;
• · two primary amino groups;
• · one ether linkage connecting the aromatic rings.

The molecular formula is C12H12N2O, and the molecular weight is approximately 200.24 g/mol. These identifiers are consistent across the Starsky Chemical product information and U.S. government chemical databases.

The positioning of the amino groups is important. In 4,4′-ODA, the amino groups occupy the para positions relative to the ether connection on both aromatic rings. This distinguishes the compound from positional isomers such as 3,4′-Oxydianiline.

That distinction should not be treated simply as a naming issue. Changing the position of functional groups changes molecular geometry and can alter how a monomer contributes to polymer-chain packing, chain mobility and other material characteristics.

For engineers and polymer researchers, the complete chemical identity—rather than the generic term “oxydianiline”—therefore matters when evaluating a material system.

Key Physical and Chemical Properties of 4,4′-ODA

The principal identification data for 4,4′-Oxydianiline are summarized above.

For material development, these values serve different purposes.

The CAS number and molecular formula establish chemical identity. This is particularly important because several oxydianiline isomers have similar names but are not chemically identical.

The molecular weight is a fundamental property used when describing and characterizing a monomer.

The melting-point range can also provide useful information during material identification and quality assessment. A measured physical property should not, however, be interpreted in isolation as proof of material suitability. Polymer-grade raw materials are normally assessed through a combination of identity, purity, impurity profile, consistency and application-specific requirements.

Why the Molecular Structure of 4,4′-ODA Matters

The role of ODA in advanced polymer chemistry is closely related to its molecular structure.

Aromatic Backbone

The two benzene rings create a relatively rigid aromatic framework.

Aromatic structures are widely used in high-performance polymer design because their carbon frameworks can provide greater structural rigidity than many flexible aliphatic structures.

This does not mean that every polymer containing an aromatic diamine will automatically exhibit high heat resistance. Final properties depend on the complete polymer architecture, the corresponding comonomers, molecular weight, processing history and other formulation variables.

The aromatic nature of ODA is one structural element contributing to the performance profile of polymer systems in which it is incorporated.

Diamine Functionality

4,4′-ODA contains two primary amino groups.

This bifunctional structure makes the molecule relevant as a monomer in polymer chemistry because both ends of the molecule can participate in polymer-chain formation with suitable complementary functional groups.

For polyimide materials, aromatic diamines are an important class of monomers. Different diamines can be selected to adjust characteristics such as backbone rigidity, chain mobility, thermal behavior and mechanical response.

ODA is therefore better understood as part of a broader polyimide monomer design system, rather than as an isolated additive.

Ether Linkage

Another defining structural feature is the oxygen atom connecting the two phenyl rings.

Compared with an entirely fused or directly connected rigid aromatic structure, an ether linkage can introduce additional conformational freedom into a polymer backbone.

This balance between aromatic rigidity and ether-linked mobility explains why ether-containing aromatic diamines have received considerable attention in high-performance polymer design.

The practical behavior of a finished polymer still depends on the complete formulation. It would therefore be inaccurate to attribute a specific final mechanical or thermal property to ODA alone.

4,4′-Oxydianiline and Polyimide Materials

Among the application areas associated with 4,4′-ODA, polyimide materials are the most technically significant.

Polyimides are a broad family of polymers containing imide structures in their polymer chains. Depending on the monomer system and processing route, they are used where combinations of thermal stability, mechanical integrity, electrical insulation or dimensional stability are required.

4,4′-ODA is one of the aromatic diamines associated with these polymer systems. Starsky Chemical’s existing product information specifically lists high-temperature polyimide films, resins and engineering polymer materials among the application areas connected with ODA.

The chemical logic behind this application is straightforward.

The diamine functionality provides the reactive sites required for polymer formation, while the aromatic rings become part of the polymer backbone. The ether bridge remains within that backbone and affects its molecular flexibility.

The resulting polymer performance cannot be predicted from ODA alone. The selected dianhydride or other complementary monomer has an equally important influence.

Material engineers therefore evaluate ODA as one component of a complete monomer pair and polymer architecture.

Applications in Other High-Performance Polymer Systems

The use of 4,4′-ODA is not limited to conventional polyimides.

Starsky Chemical’s current technical description also associates the material with several related polymer families, including polyetherimides, polyesterimides, polymaleimides and polyarylamide-related systems. It additionally identifies applications connected with heat-resistant epoxy, polyurethane and other polymer materials.

These application areas share one common engineering objective: the molecular structure of the polymer is designed for more demanding thermal or mechanical conditions than would normally be expected from general-purpose plastics.

The role of ODA differs between polymer systems. It may function as a structural monomer or as part of a more complex resin chemistry.

It is therefore inaccurate to describe 4,4′-ODA as producing one fixed level of heat resistance or mechanical performance.

A finished material’s properties are controlled by factors such as:

• · overall polymer backbone structure;
• · comonomer selection;
• · molecular-weight distribution;
• · degree of crosslinking where applicable;
• · impurity profile;
• · thermal history;
• · processing conditions;
• · intended service environment.

For B2B technical evaluation, these variables are more meaningful than broad claims such as “high performance” without supporting material data.

Why Raw-Material Quality Matters in Polymer Applications

When an aromatic diamine is incorporated into a polymer system, raw-material quality can affect process consistency and final material evaluation.

Chemical identity is the first requirement. Similar names or related positional isomers should not be treated as interchangeable materials without technical validation.

Purity is another relevant parameter. Unwanted organic or inorganic species can interfere with polymer chemistry or create variability between production batches.

Batch consistency is important when a formulation moves from laboratory development into repeat production. A technically acceptable sample does not automatically demonstrate long-term production consistency.

Documentation is equally important. Industrial users typically review specifications and appropriate safety documentation together with their own incoming quality-control requirements.

For critical polymer applications, acceptance criteria should therefore be based on the user’s validated material specification rather than solely on a general product description.

4,4′-ODA vs 3,4′-ODA: Why the Isomer Matters

4,4′-Oxydianiline and 3,4′-Oxydianiline share the same molecular formula and molecular weight, but their amino groups occupy different positions on the aromatic rings.

4,4′-ODA is CAS 101-80-4, while 3,4′-ODA is CAS 2657-87-6. The latter is also identified as 3-(4-aminophenoxy)aniline with the same molecular formula, C12H12N2O, and molecular weight of 200.24 g/mol.

The distinction illustrates an important principle in polymer chemistry:

Changing the position of a functional group changes molecular symmetry and geometry. In polymer design, those differences can influence how chains organize and how much conformational freedom exists along the backbone.

For this reason, engineers should specify the required oxydianiline isomer clearly rather than relying only on the abbreviated term “ODA.”

Safety and Regulatory Considerations

Frequently Asked Questions About 4,4′-Oxydianiline

Conclusion