Dimethyl silicone oil: characteristics, applications, and future prospects
abstract
As the core representative of organic silicon materials, polydimethylsiloxane (PDMS) has demonstrated irreplaceable application value in many fields such as industry, medical, daily chemical, electronics, etc. due to its unique molecular structure and excellent performance. This article systematically analyzes the core advantages of dimethyl silicone oil from four dimensions: molecular structure, physical and chemical properties, application fields, and future development trends. Combined with the latest research progress, it explores its innovative application directions in high-end manufacturing, new energy, biomedical and other fields.


Keywords: dimethyl silicone oil; Molecular structure; Physical and chemical properties; Application areas; Future Trends


1、 Introduction
Polydimethylsiloxane (PDMS) is a linear polymer with silicon oxygen bonds as the main chain and methyl groups as the side groups. Its molecular formula can be expressed as (CH3) ∝ SiO [Si (CH3) ₙ O] ₙ Si (CH3) ∝. Since its industrial production in the 1940s, dimethyl silicone oil has rapidly become one of the most widely used varieties in silicone materials due to its excellent high and low temperature resistance, chemical stability, electrical insulation, and physiological inertness. This article will systematically analyze the core advantages of dimethyl silicone oil from four dimensions: molecular structure, physical and chemical properties, application fields, and future development trends.


2、 Molecular Structure and Basic Characteristics of Dimethyl Silicone Oil
The molecular chain of dimethyl silicone oil consists of alternating silicon oxygen bonds (Si-O) and two methyl groups (CH3), and its basic unit is - Si (CH3) ₂ - O. Depending on the degree of polymerization, the molecular weight of dimethyl silicone oil can range from several hundred to tens of thousands, with viscosity ranging from 1 cSt to several million cSt. This molecular structure endows dimethyl silicone oil with the following characteristics:


High and low temperature resistance: It can be used for a long time within the range of -50 ℃ to 200 ℃, and can withstand high temperatures of 300 ℃ in the short term, which is better than most mineral oils.
Chemical stability: It has excellent tolerance to acids, bases, oxidants, etc., and its viscosity only increases by 10% after 16 hours of thermal aging at 200 ℃.
Electrical insulation: With a volume resistivity of up to 10 ¹⁴Ω· cm, it is suitable for insulation of high-voltage electrical equipment.
Physiological inertness: Rat oral LD ₅₀>35g/kg, non-toxic and not decomposed by body fluids, in compliance with FDA medical device lubrication certification.
3、 Core physical and chemical properties of dimethyl silicone oil
（1） Thermal oxidation stability
Dimethyl silicone oil exhibits excellent thermal oxidation stability with a viscosity change of less than 5% after continuous use for 1000 hours at 150 ℃. This characteristic makes it an ideal material for high-temperature environments such as aerospace, electronics, and electrical appliances. For example, in the lubrication system of aircraft engines, dimethyl silicone oil can withstand extreme temperature changes, ensuring the long-term stable operation of the equipment.


（2） Rheological properties
Dimethyl silicone oil has excellent shear stability, with a shear resistance 20 times higher than high-quality mineral oil, making it suitable for high shear conditions. Its viscosity temperature coefficient is only 0.31~0.61, much lower than mineral oil (>0.8), ensuring consistent performance over a wide temperature range.


（3） Surface and Interface Characteristics
The surface tension of dimethyl silicone oil is 15.9-21.5mN/m, and it has excellent defoaming performance and hydrophobic properties. For example, in the textile industry, fabrics coated with dimethyl silicone oil have a contact angle greater than 130 °, significantly improving waterproofing; In cosmetics, dimethyl silicone oil can form a nano scale waterproof film, enhancing the skin feel and durability of the product.


（4） Optical performance
The transmittance of dimethyl silicone oil in the visible light region (thickness 1mm) reaches 100%, with a UV cutoff wavelength of 280nm (transmittance<10%), and the refractive index can be adjusted within the range of 1.390~1.410 by viscosity control. This characteristic makes it widely used in fields such as optical lenses and displays.