Poly(dimethylsiloxane)
[CAS# 9016-00-6]

Identification

• Classification: API >> Digestive system medication >> Acid and gastric mucosal protective drugs
• Name: Poly(dimethylsiloxane)
• Synonyms: Dimethylpolysiloxane; Dimethicone; Simethicone
• Molecular Formula: (C₂H₆OSi)_n
• CAS Registry Number: 9016-00-6
• EC Number: 618-493-1
• SMILES: C[Si](=O)C

Properties

• Density: 0.980 g/mL (Expl.)
• Melting point: < -40 ºC (Expl.)
• Boiling point: > 205 ºC (Expl.)
• Flash point: 321 ºC - closed cup (Expl.)
• Solubility: water: insoluble (Expl.)

Safety Data

• Safety Description: S24/25

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Chronic hazardous to the aquatic environment	Aquatic Chronic	4	H413
Eye irritation	Eye Irrit.	2	H319
Serious eye damage	Eye Dam.	1	H318
Skin irritation	Skin Irrit.	2	H315

Discovory and Applicatios

Poly(dimethylsiloxane), commonly abbreviated as PDMS, is a silicon-based polymer with the repeating structural unit –\[Si(CH₃)₂–O]–. It consists of a backbone of alternating silicon and oxygen atoms, with two methyl groups attached to each silicon. This unique structure imparts remarkable flexibility, low glass transition temperature, chemical inertness, and thermal stability, making PDMS one of the most versatile and widely used silicones.

The discovery of PDMS traces back to the early 20th century when chemists began exploring organosilicon compounds. In the 1940s and 1950s, advancements in polymerization techniques, particularly ring-opening polymerization of cyclic siloxanes, allowed the production of high-molecular-weight PDMS. Its properties, such as non-toxicity, hydrophobicity, and low surface energy, quickly attracted attention for a wide range of industrial and biomedical applications.

Applications of PDMS are extensive due to its unique physical and chemical characteristics. In industrial and consumer products, PDMS serves as a lubricant, anti-foaming agent, and surface modifier. Its flexibility and low surface energy make it ideal for coatings, sealants, and adhesives, where it enhances water repellency, reduces friction, and provides thermal and chemical stability.

In the biomedical field, PDMS is used for medical devices, implants, and drug delivery systems. Its biocompatibility, oxygen permeability, and chemical inertness allow it to be safely used in contact with tissues and fluids. Additionally, PDMS is employed in microfluidics, where its elastomeric properties enable the fabrication of flexible microchannels and lab-on-a-chip devices.

PDMS is also important in electronics and optics, serving as an encapsulant for components, a flexible substrate, and in the production of elastomeric lenses and optical devices. Its transparency, low refractive index, and stability under a range of environmental conditions make it suitable for these high-precision applications.

The industrial synthesis of PDMS typically involves the hydrolysis and condensation of dimethyldichlorosilane to produce silanol-terminated oligomers, which are subsequently polymerized via equilibrium ring-opening polymerization. By controlling the degree of polymerization and crosslinking, manufacturers can produce PDMS with tailored viscosity, elasticity, and mechanical properties suitable for specific applications.

Overall, poly(dimethylsiloxane) exemplifies a highly adaptable polymer whose combination of chemical stability, flexibility, and biocompatibility has made it a cornerstone material in multiple industries, ranging from consumer goods to advanced medical and technological applications.

References

2014. Rhodium-catalyzed transfer hydrogenation with aminophosphines and analysis of electrical characteristics of rhodium(I) complex/n-Si heterojunctions. Applied Organometallic Chemistry, 28(6).
DOI: 10.1002/aoc.3140

2012. Synthesis of platinum acetylide complexes and their application in curing silicone rubber by hydrosilylation. Applied Organometallic Chemistry, 26(6).
DOI: 10.1002/aoc.2881

2012. Synthetic and natural silica-aluminates as inorganic acidic catalysts in ring opening polymerization of cyclosiloxanes. Applied Organometallic Chemistry, 26(6).
DOI: 10.1002/aoc.2873