Talk about polyether modified heptamethyl trisiloxane (HC-YM9362) : structural characteristics, synthesis process and innovative applications

Ⅰ. Product Overview

Polyether-Modified Heptamethyltrisiloxane is a high-performance silicone surfactant, which is composed of heptamethyltrisiloxane and polyether segments bonded by chemical bonds. Its molecular structure combines the hydrophobicity of siloxane and the hydrophilicity of polyether, forming a unique "amphiphilic" characteristic and is widely known as a "super spreader". This compound has shown revolutionary application value in the fields of cosmetics, agriculture, coatings, etc., and is particularly known for its ultra-low surface tension and dynamic wetting ability.

It enables sprayed agricultural chemicals to perform better. Compared with traditional surfactants, it is easier to adhere to leaves, has super spreading and wetting properties, penetrates faster through pores and is resistant to rain erosion. This excellent spreading ability means that only a small amount of pesticide spray is needed to achieve ideal coverage and control effects, and the resistance to rain erosion increases the shelf life of the pesticide. This product can save up to 70% of water when spraying pesticides. This can reduce waste and reduce the amount of pesticides lost to soil and groundwater, thereby reducing pesticide residues in the environment.

Ⅱ. Structure and physical and chemical properties

Technical indicators

Chemical name: Polyether modified heptamethyl trisiloxane

CAS No.: 27306-78-1

Density (25℃, g/cm³): 1.00-1.05

Equivalent to: Dow Corning: Q2-5211 Momentive: Silwet 408 Degussa: S 240

Appearance: Colorless to light yellow transparent liquid

Active content: 100%

Viscosity: 20-60cs

Surface tension (0.1%.aq): ≤22mN/m

Structural formula:

1. Molecular structure

Core skeleton: Heptamethyltrisiloxane (chemical formula: (CH₃)₃Si-O-Si(CH₃)₂-O-Si(CH₃)₃ ), with a trisiloxane chain and seven methyl groups.

Modified groups: Polyether chains (such as PEG/PPG block copolymers) are introduced through hydrosilylation reaction to form a "comb-like" structure connected by Si-OC bonds

(example formula: (CH₃)₃Si-O-Si(CH₃)₂-O-Si(CH₃)₂-(CH₂)₃-O-(CH₂CH₂O)ₙ-(CH₂CH(CH₃)O)ₘ-R ).

2. Key performance

Surface activity: The surface tension can be as low as 20-25 mN/m (pure water is 72 mN/m), which is significantly better than traditional surfactants.

Dynamic wetting: contact angle <10°, achieving instantaneous spreading of liquid on hydrophobic surfaces (such as lotus leaves and polypropylene films).

Thermal stability: temperature range is -40°C to 200°C, suitable for high temperature processing environment.

Environmental compatibility: Biodegradable (60-day degradation rate>70% under OECD 301 standard), in line with the trend of green chemistry.

Ⅲ. Synthesis process

1. Core steps

Raw material preparation:

Heptamethyltrisiloxane: prepared by hydrolysis and condensation of methylchlorosilane.

Terminal allyl polyether: synthesized by ring-opening polymerization of ethylene oxide (EO) and propylene oxide (PO).

Hydrosilylation reaction:

                                                                                              Pt催化剂

(CH₃)₃Si-O-Si(CH₃)₂-O-Si(CH₃)₂-H +CH₂=CH-PEG/PPG-R      →         目标产物

Reaction conditions: temperature 80-120°C, nitrogen protection, catalyst dosage 50-200 ppm.

2. Process Optimization

Molecular weight control: Customize the hydrophile-lipophile balance (HLB value range 8-16) by adjusting the EO/PO ratio and degree of polymerization (n/m value).

By-product suppression: Membrane separation technology is used to remove unreacted polyether, with a purity of over 98%.

Ⅳ. Application fields

PMHTS has been widely used in many fields due to its unique performance:

Pesticide field:

Improve the efficacy of pesticides: PMHTS can reduce the surface tension of pesticide solutions, improve their spreadability and permeability on plant leaves, and enable pesticides to better cover and penetrate into the parts of pests and diseases, thereby improving their efficacy.

Reduce the use of pesticides: Since PMHTS can improve the utilization rate of pesticides, it can reduce the use of pesticides and reduce environmental pollution.

Reduce pesticide drift: PMHTS can increase the adhesion of pesticide droplets and reduce their drift, thereby protecting non-target crops and the environment.

Solubilizing agent: Some poorly soluble pesticides require the addition of co-solvents to prepare them into aqueous solutions. PMHTS can be used as a solubilizing agent to help the pesticides dissolve.

1. On-site mixing:

Add 50g HH-212 to every 200kg spray. If you need to promote absorption, further improve the efficacy or reduce the spray volume, you can increase the dosage appropriately. Generally, the dosage in fungicides is 0.01~0.05%, the dosage in herbicides is 0.025~0.1%, and the dosage in insecticides is 0.025~0.1%.

When using, first add 80% water to dissolve the pesticide, then add HH-212 and 20% water and mix evenly.

HH-212 is best used under the following conditions: ① The pH value is controlled within the range of 5-9, ② Use within 24 hours after preparation

2. Preparation of pesticide formulations:

It is recommended to add 0.5~8% of the pesticide stock solution. It is recommended to adjust the PH value of the pesticide formula to 6~8. Users should adjust the amount of HH-212 according to the type and formula of pesticide to achieve the best effect. Compatibility test should be done before use.

Coatings field:

Improve the leveling of coatings: PMHTS can reduce the surface tension of coatings, allowing them to spread better on the surface of the substrate and form a smooth coating film.

Improve the wettability of coatings: PMHTS can improve the wettability of coatings to substrates and enhance the adhesion of coatings.

Prevent paint shrinkage: PMHTS can eliminate the shrinkage phenomenon on the paint surface and improve the quality of the coating.

Dispersant: It can be used as a dispersant for pigments and fillers to improve the stability of coatings.

Cosmetics field:

Improve skin feel: PMHTS can give cosmetics a silky, smooth skin feel, making them easier to apply and absorb.

Improve moisturizing properties: PMHTS can form a protective film on the skin surface, reduce water evaporation and improve skin moisturizing properties.

Emulsifier: It can be used as an emulsifier to prepare lotions and creams.

Dispersant: It can be used as a dispersant for pigments and powders and is used in cosmetic products.

Textile field:

Softener: PMHTS can give fabrics a soft and smooth touch and improve the comfort of fabrics.

Waterproofing agent: PMHTS can improve the waterproof performance of fabrics, making them have a certain water resistance.

Antistatic agent: PMHTS can eliminate static electricity on fabrics and reduce dust absorption.

Wetting agent: It can be used as a wetting agent in the textile printing and dyeing process to increase the coloring rate of the dye on the fabric.

Other areas:

Cleaning agent: PMHTS can reduce the surface tension of the cleaning agent and improve its ability to remove dirt.

Papermaking industry: used as defoaming agent and deaerator to improve paper quality.

Polyurethane foam: acts as a foam stabilizer to improve the structure and properties of foam.

Personal care products: used as a conditioner and emulsifier in shampoo, shower gel and other products.

Oil extraction: It can be used as a viscosity reducer to reduce the viscosity of crude oil and improve extraction efficiency.

V. Development Trend

As people pay more and more attention to environmental protection and sustainable development, the requirements for PMHTS are getting higher and higher. The future development trends are mainly concentrated in the following aspects:

Develop environmentally friendly PMHTS: Use more environmentally friendly raw materials and processes, reduce pollution during the production process, and develop PMHTS with better biodegradability.

Customized PMHTS: Design and synthesize PMHTS with specific properties, such as high temperature resistance, high pH stability, etc., according to different application requirements.

Compound application: PMHTS can be compounded with other types of surfactants or additives to achieve synergistic effects and improve their performance.

Expand new application areas: Explore the application of PMHTS in emerging fields such as new energy, biomedicine, and smart materials.

VI. Conclusion

As a surfactant with excellent performance, polyether-modified heptamethyltrisiloxane (PMHTS) has been widely used in pesticides, coatings, cosmetics, textiles and other fields due to its unique molecular structure and excellent physical and chemical properties. With the continuous development of science and technology, the application field of PMHTS will continue to expand, and it will play a more important role in future industrial production and people's daily life. In-depth understanding of its characteristics and reasonable selection and application according to specific applications will help improve product performance, reduce production costs, and contribute to sustainable development.

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