Polysulfide rubber
[CAS# 63148-67-4]

Identification

• Classification: Catalysts and additives >> Polymer
• Name: Polysulfide rubber
• Synonyms: 1-[2-(2-hydroxy-3-piperidin-1-ylpropoxy)phenyl]-3-phenylpropan-1-one
• Molecular Formula: C₂₃H₂₉NO₃
• Molecular Weight: 367.48
• CAS Registry Number: 63148-67-4
• SMILES: C1CCN(CC1)CC(COC2=CC=CC=C2C(=O)CCC3=CC=CC=C3)O

Properties

• Density: 1.1±0.1 g/cm³ Calc.^*
• Boiling point: 549.6±50.0 ºC 760 mmHg (Calc.)^*
• Flash point: 286.2±30.1 ºC (Calc.)^*
• Index of refraction: 1.572 (Calc.)^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Discovory and Applicatios

Polysulfide rubber is a class of synthetic elastomers characterized by the presence of multiple sulfur atoms within the polymer backbone. These polymers are typically formed by the condensation of organic dihalides with sodium polysulfides, producing long chains with repeating –Sx– linkages. The resulting materials are widely known for their chemical resistance, flexibility, and barrier properties, which make them suitable for a variety of industrial and commercial applications.

The discovery and development of polysulfide rubber date back to the early 20th century, when researchers sought materials capable of resisting solvents and fuels that degraded natural rubber. The introduction of sulfur linkages into the polymer chain was found to improve chemical stability, particularly against hydrocarbons, oils, and polar solvents. This property distinguishes polysulfide rubbers from other elastomers, such as polybutadiene or natural rubber, which are susceptible to swelling and degradation in aggressive chemical environments.

Polysulfide rubbers are typically synthesized by reacting a halogenated organic compound, such as an alkyl or aryl dihalide, with a polysulfide salt. The polysulfide salts contain chains of sulfur atoms and react with the dihalide through a nucleophilic substitution mechanism to form the polymer backbone. By controlling the length of the polysulfide chains and the ratio of reactants, manufacturers can adjust properties such as flexibility, tensile strength, and cure time. End-capping of the polymer chains with thiol groups is also used to improve stability and control crosslinking during processing.

The chemical structure of polysulfide rubber imparts several important properties. The sulfur linkages in the backbone confer excellent resistance to hydrocarbon solvents, gasoline, and lubricating oils, making these rubbers ideal for applications such as fuel hoses, gaskets, and sealing materials. Additionally, the flexibility of the polymer allows it to maintain elasticity over a wide temperature range, while the presence of sulfur enhances adhesion to metals and other substrates. The combination of chemical resistance, elasticity, and durability gives polysulfide rubber a unique position among synthetic elastomers.

Polysulfide rubbers are usually processed as liquid prepolymers or pastes, which are then cured with additional sulfur or other crosslinking agents. Curing typically involves oxidative crosslinking, which links polysulfide chains together to form a three-dimensional network. The degree of crosslinking directly affects the mechanical properties, including tensile strength, elongation at break, and hardness. Controlled curing conditions allow manufacturers to tailor the properties of the final material to specific requirements, whether for flexible sealants or more rigid gaskets.

In practical applications, polysulfide rubber is widely used in sealants for construction, aerospace, and automotive industries. Its resistance to water, fuels, and weathering makes it ideal for caulking joints in buildings, sealing airplane fuel tanks, and providing durable gaskets in engines. The material’s low permeability to gases and liquids also allows it to serve as a protective barrier in chemical storage containers and pipelines. In addition, its adhesive properties enable it to bond strongly to concrete, metals, and glass, expanding its utility in structural applications.

Polysulfide rubber is also notable for its thermal stability. Although it softens at elevated temperatures, it maintains elasticity over a broad range and exhibits low shrinkage upon curing. This thermal performance, combined with chemical resistance, ensures long-term durability in demanding environments. Additionally, the polymer can be blended with fillers, plasticizers, and stabilizers to enhance specific properties such as flame resistance, abrasion resistance, or flexibility at low temperatures.

Overall, polysulfide rubber represents a class of high-performance elastomers whose combination of chemical resistance, elasticity, and adhesion properties makes it invaluable in industrial and commercial applications. Its development marked an important advance in synthetic elastomer technology, providing materials capable of withstanding harsh chemical environments while maintaining mechanical integrity. The versatility of polysulfide rubber continues to make it a preferred choice for gaskets, sealants, hoses, and other applications where durability and chemical stability are critical.

References

2023. Synergistic Effect and Electrical Properties of Microporous Liquid Metal/Carbon Nanotube Polymer Sponge. Macromolecular Rapid Communications, 44(21).
DOI: 10.1002/marc.202300307