High-Purity Hydroxy/Carboxyl Reactive Siloxane Monomer—Fluorine-Free Waterproofing Solution for Polyurethane Changfu Chemical

In an era of increasingly stringent environmental regulations and rising performance expectations across textile and industrial coatings, the elimination of persistent organic pollutants such as PFOA (perfluorooctanoic acid) and PFOS (perfluorooctane sulfonate) has become a global imperative. These perfluorinated compounds, long used in traditional waterproofing treatments, are now linked to severe environmental persistence, bioaccumulation, and health risks. In response, Changfu Chemical has pioneered a breakthrough fluorine-free waterproofing platform based on high-purity, small-molecule functional siloxane monomers. Specifically designed for waterborne polyurethane (PU) systems, this solution addresses five critical performance bottlenecks: high water repellency, strong wash resistance, ultra stability, soft hand feel, and high hydrostatic pressure. It serves as a universal, high-quality raw material for outdoor fabrics, technical textiles, and premium garment finishing.

Core Advantages:

• Fluorine-free for greater safety: Free from PFOA/PFOS, compliant with stringent international export standards such as REACH and OEKO-TEX.
• Chemical bond anchoring, no migration or oil leaching: Achieved through precise functional group design and deep cross-linking with PU-NCO, offering excellent resistance to washing, abrasion, and soap washing.
• Small molecule strong permeability: Low-molecular-weight structure penetrates deeply into fiber interstices rather than coating the surface, forming a dense, flexible hydrophobic membrane. Significantly boosts hydrostatic pressure resistance while preserving the fabric’s inherent breathability and air permeability, avoiding stuffiness and ensuring all-day comfort.
• Silky and soft to the touch: Eliminates the stiff, rough hand feel typical of traditional waterproof finishes. Maintains the fabric’s natural fluffy, supple texture and drape; ideal for down jackets, windbreakers, outdoor sportswear, and lightweight textiles where comfort and softness are critical.
• Batch stability and easy compatibility: Product purity exceeds 95%, with consistent quality across batches. Demonstrates excellent compatibility with water-based PU systems, acrylics, and common textile auxiliaries, low gelation tendency and good process adaptability for padding, dipping, or coating. Ensures trouble-free mass production, reliable reproducibility, and long-term storage stability.

Four major types of small molecule polysiloxane monomers, precisely matching the PU-NCO cross-linking system:

1.   Monofunctional Hydroxy Polysiloxane

• Characteristics: The monofunctional hydroxy group covalently anchors to the PU framework, with the siloxane chain extending outward, creating a low surface energy interface. Small molecules with high permeability, balancing a silky, fluffy feel with breathability, no silicone migration, and no oil blooming.
• Application scenarios: High-demand scenarios where water repellency and tactile feel are equally important, such as in jackets and down fabric.
• Representative product: Changfu^® PO24 {3-(2-hydroxyethoxy) propylbis(trimethylsiloxy)methylsilane; CAS: 23785-50-4}

2.    Di-end Hydroxy Polysiloxane

• Characteristics: One end is anchored to the PU backbone via hydroxyl chemical bonds, while the other end features an inert silicon chain stretching outward; small molecules can easily penetrate fiber gaps, resulting in excellent low surface energy on the fabric surface, prominent lotus-leaf water-repellent effect, silky smoothness, bulkiness, and breathability without stuffiness; stable curing anchorage prevents silicon migration and shifting, balancing water repellency, hand feel, and fabric permeability.
• Application scenarios: Workwear, home textiles, woven fabrics, and other high durability requirement scenarios.
• Representative product: Changfu^® BPO12 {1,3-Bis(3-(2-hydroxyethoxy) propyl)-1,1,3,3-tetramethyldisiloxane; CAS: 441307-02-4}

3.    Monofunctional Di-hydroxy Polysiloxane

• Characteristics: Highly active design with single-ended bifunctional groups, doubling the NCO reaction efficiency; stronger anchoring force, higher crosslinking density, and more uniform penetration of small molecules; enhancing the toughness of PU films, bending resistance, crack resistance, washing resistance and durability, while retaining the silky smooth hand feel of silicone-based materials; excellent emulsion compatibility, wide curing window, curable at low temperatures, solving the problem of excessively hard PU film formation.
• Application scenario: Systems that require a balance of toughness, tactile feel, and low-temperature processing adaptability.
• Representative product: Changfu^® BPO24 {[3,3-Bis(hydroxymethyl)butoxy] propylbis(trimethylsiloxy)methylsilane; CAS: 4262-92-4}

4.    Monofunctional Carboxyl-terminated Polysiloxane

• Characteristics: The carboxyl group reacts controllably with -NCO to form a stable amide bond, exhibiting resistance to hydrolysis and sweat stains, with wash fastness superior to hydroxyl systems. The emulsion has good stability, is resistant to gelling, and has a long shelf life. The fabric surface is fine, dry, and has low yellowing, meeting European and GRS environmental standards.
• Application scenario: High-end fluorine-free waterproof system, particularly suitable for scenarios that require both environmental protection and high durability.
• Representative product: Changfu^® CA24 {Carboxylbis(trimethylsiloxy)methylsilane}

Changfu Chemical's series of small molecule polysiloxane products, with their stable quality, excellent performance, and good process compatibility, has become the ideal choice for fluorine-free waterproof systems in water-based PU. Moving forward, guided by technological innovation and green chemistry principles, Changfu Chemical will continue to develop more efficient, eco‑friendly, and cost‑competitive new material solutions, empowering customers to achieve high performance and sustainability in a wide range of applications. (Note: The specific application effects need to be determined based on actual usage conditions. We welcome you to contact our technical team for more product information and technical support)

If you need to learn more or obtain additional product information and related application details, please contact:

Mobile: (+86)181-6277-0058

Email: sales@cfsilanes.com

Key words: Siloxane monomer; Waterborne polyurethane; Hydroxy/Carboxyl; Changfu chemical.