Silane-Terminated Polyether (MSTP, commonly abbreviated as MS Polymer or STPE) is a class of functional polymers with a polyether backbone and terminal or side-chain silane groups. Below is a systematic overview of its key information:

1. Structure and Synthesis

Structural Features: The backbone consists of polyether (e.g., EO/PO copolymer), with terminal or side-chain hydrolysable silane groups (e.g., methoxysilane) chemically grafted.

Synthesis Methods:

End-Capping Modification: The terminal hydroxyl groups of polyether react with isocyanate silanes (e.g., isocyanatopropyltrimethoxysilane) to form urethane-linked silane-terminated structures.

Direct Grafting: Silane coupling agents (e.g., epoxy silanes) react with active groups on the polyether chain.

2. Curing Mechanism

Moisture Curing: Silane groups (e.g., -Si(OCH₃)₃) hydrolyze upon exposure to moisture, forming silanols (-Si(OH)₃), which subsequently condense into a 3D Si-O-Si network.

Catalyst-Free: Typically relies on ambient humidity, but organotin or eco-friendly catalysts (e.g., titanates) can accelerate curing.

3. Performance Characteristics

Advantages:

Eco-Friendliness: Solvent-free, low VOC, compliant with RoHS and other regulations.

Weather Resistance: UV-resistant, thermally stable (-40°C to 150°C), and hydrolysis-resistant.

Adhesion: Strong bonding to metals, glass, concrete, plastics, and other substrates.

Flexibility: High elongation (>500%), suitable for dynamic displacement applications.

Limitations:

Higher cost compared to conventional polyurethanes.

Requires moisture-proof storage (silane groups may pre-cure).

4. Applications

Construction Sealants: Curtain wall joints, window/door sealing (replacing silicone sealants without pollution).

Automotive Industry: Windshield bonding, interior component fixation.

Electronic Encapsulation: Waterproof potting compounds (resistant to humid environments).

Coatings & Waterproofing: Elastic coatings, roof waterproofing.

5. Development Trends

High-modulus formulations (for structural bonding).

Fast-curing variants.

6. Research Hotspots

Nanocomposites: Incorporation of nano-SiO₂ or carbon nanotubes to enhance mechanical/thermal properties.

Dynamic Bond Design: Introduction of reversible siloxane bonds for self-healing functionality.

Biodegradability: Exploration of degradable polyether segments (e.g., PCL-modified).

Summary

Silane-terminated polyethers have emerged as a critical material in sealants and adhesives due to their eco-friendliness, balanced performance, and broad applicability, particularly in high-end construction and new energy vehicles. Future advancements will focus on high-performance formulations, functionalization, and sustainability improvements.