In reactive modification of polyurethane, polyester, and epoxy resins, plus hydrophilic lubrication and mold release, how to permanently embed polydimethylsiloxane (PDMS) low-surface-energy, flexible, weatherable segments into the organic backbone—rather than physically blending oil that bleeds and migrates—is the core proposition of reactive organosilicone modification. Traditional hydroxyl-terminated silicone with Si-OH often reacts through Si-O-C routes with isocyanate, carboxyl, anhydride, or epoxy groups; under humidity/heat the linkage may retro-hydrolyze, causing silicone bleeding, hand-feel decay, and coating haze. Ordinary polyether modifiers cannot simultaneously deliver PDMS slip and wide-temperature flexibility. With waterborne PU, electronic epoxy encapsulation, and high-end leather/coatings demanding "chemical embedding, hydrolysis resistance, low migration", finding a "bis carbon-hydroxyl, Si-C connected, low-viscosity, easily copolymerizable" reactive silicone oil has become a key formulation issue. Addressing this, Anhui IOTA Silicone Oil Co., Ltd. officially launches Carbon Hydroxy Silicone Oil IOTA 28300 (carbinol-terminated PDMS, α,ω-Bis(3-(2-hydroxyethoxy)propyl)polydimethylsiloxane). Characterized by "appearance: colorless transparent oily liquid; density (25℃) 0.972–0.982 g/cm³; OH value 1.60–2.00 mmol/g; viscosity (25℃) 30–50 mm²/s; volatiles ≤2.00%; typical properties not as quality specification", backed by "bis C-OH + Si-C non-hydrolyzable anchor + PDMS flexible chain + low-viscosity dispersibility", it serves as the "embedding choice" for resin reactive modification and hydrophilic interfaces, achieving the leap from "physically blended silicone bleeds" to "carbon-hydroxyl Si-C copolymer new embed". System Positioning: Carbinol-Terminated PDMS vs. Silanol-Terminated PDMS/Ordinary Polyether Modifier IOTA 28300 belongs to bis(hydroxyalkyl)-terminated PDMS, distinct from silanol-terminated hydroxyl silicone and non-functional PDMS base oil. Silanol terminators (Si-OH) reacting with -NCO or organic groups tend to form Si-O-C and may self-condense, giving a narrow gel-free window in scale-up; IOTA 28300 anchors hydroxyls at the end of propyl-oxyethyl carbon chains (C-OH) through Si-C to the siloxane backbone, reacting with isocyanate, carboxyl, anhydride, and epoxy to introduce PDMS via Si-C, avoiding silanol self-polymerization and reducing retro-hydrolysis. Versus pure polyether soft segments, it adds PDMS low surface energy, flexibility, and temperature breadth; versus simple oil blending, it is reactive embedding rather than migratory externals. Molecular Architecture: PDMS Backbone + Bis Hydroxyethoxypropyl Primary Alcohol + Si-C Fixing The core design of IOTA 28300 comes from α,ω-bis(3-(2-hydroxyethoxy)propyl)polydimethylsiloxane:

• Bis Primary Alcohol C-OH: Each end carries hydroxyethoxypropyl with primary -CH₂OH, highly reactive toward isocyanate (-NCO), carboxyl/anhydride (-COOH/-CO-O-CO-), and epoxy, functioning as a macrodiol in polycondensation/addition.
• Si-C Non-Hydrolyzable Anchor: Active ends connect to the siloxane via propyl Si-C bonds rather than Si-O-C; once welded into the organic polymer, the siloxane segment resists humid-heat cleavage and bleeding, giving better hydrolysis stability than silanol routes.
• PDMS Flexible Low-Energy Chain: The central PDMS provides low surface energy, flexibility, weatherability, and wide-temperature performance; 30–50 mm²/s low viscosity enables direct dispersion into prepolymers, epoxy components, or waterborne systems with less high-shear local gelation.
• OH Value Defines Chain Length: OH 1.60–2.00 mmol/g corresponds to a controlled average segment, usable as PU chain-extending/copolymer diol and for stoichiometric polyester/epoxy ring-opening without excessive MW drift.
• Clear Physicochemical Baseline: Density 0.972–0.982 and volatiles ≤2.00% support dosing and process purification; typical values are for selection only, not shipment硬specification.

Performance Leap: From "External Oil Migration" to "Chemical Embedding Without Bleed" Introducing IOTA 28300 brings the following improvements:

• Polyurethane Modification: As bis-terminal diol in soft segments, it gives synthetic leather and waterborne PU coatings silky feel, low friction, anti-block, and humid-heat stability without external oil migration.
• Polyester/Epoxy Modification: Copolymerizes via carboxyl, anhydride, or epoxy ring-opening to lower surface tension, improve leveling and wetting, and enhance water resistance, weatherability, and flexibility for electronic encapsulation, protective coatings, and composite matrices.
• Hydrolysis-Stable Embedding: Introducing PDMS via Si-C offers better stability in moist/high-humidity-high-temperature service than Si-OH→Si-O-C, reducing silicone bleed, tack return, and coating haze.
• Hydrophilic Lubrication/Release: Terminal hydroxyethoxy imparts partial hydrophilicity and washability; suitable as hydrophilic lubricant for metal cold working/plastic molding/rubber processing and as low-residue mold release.
• Low-Viscosity Mixing: 30–50 mm²/s room-temperature flow supports pumping, prepolymer dropping, and lab-to-scale transfer.

Application Penetration: From Waterborne PU to Epoxy Encapsulation IOTA 28300 covers reactive modification scenarios:

• Waterborne/2K Polyurethane: Synthetic leather, wood coatings, industrial anticorrosion, automotive OEM/refinish, plastic/electronic coatings for slip and mar resistance plus low-surface-energy leveling.
• Polyester Systems: Polyester resin, fiber, and film modification for flexibility, antistatic hand-feel, and surface slip.
• Epoxy Resins: Electronic encapsulation, wind-blade/high-end composite matrix modification for moisture resistance, flexibility, and low internal stress.
• Hydrophilic Lubrication: Metal cold working, plastic injection, rubber product low-friction interfaces.
• Mold Release: Plastic molding, rubber vulcanization, precision parts with low residue.

IOTA Technical Guide: Stoichiometric Embedding, Room-Temperature Seal

• Application: Dose by active-group equivalents of target resin. In PU, replace part of polyether/polyester diol as silicone soft segment; in polyester/epoxy, add bis C-OH by carboxyl/anhydride or epoxy ring-opening equivalents. Recommend 0.5–5% of total resin mass for preliminary trials on hand-feel, compatibility, and storage stability before scale-up.
• Compatibility: Reactive with isocyanate, carboxylic acid, anhydride, epoxy resins; avoid prolonged strong acid/strong base that may degrade the siloxane backbone; separate from strong oxidants.
• ⚠️ Taboo: Store sealed at room temperature; reseal after use to prevent moisture pickup and volatilization. Read MSDS and label before use, wear proper PPE. Control water in isocyanate systems to avoid CO₂ bubbles. Run clarity tests—some acrylic/high-transparency systems may turn hazy due to silicone phase separation.
• Storage: 25L or 200L inner-coated steel drum, net 20kg or 195kg; sealed at room temperature, shelf life 12 months from production. Unlike IOTA 5560 (epoxysilane, 5/10/200kg plastic, 1yr) and IOTA 1524 (ureidosilane, multi-size, 6 months), IOTA 28300 is low-volatile oil in inner-coated steel drums, 12-month shelf life.

Industry Insight: The core value of carbinol-terminated silicone oil lies in "bis C-OH for organic copolymerization, Si-C for hydrolysis-stable non-bleeding, PDMS for low-energy flexibility". IOTA 28300, with "colorless oily, density 0.972–0.982, OH 1.60–2.00 mmol/g, viscosity 30–50 mm²/s, volatiles ≤2.00%, PU/polyester/epoxy modification + hydrophilic lubrication/release, 25L/200L inner-coated steel 20/195kg, 12 months" hard parameters, fills the Si-C embedding link of domestic reactive carbinol silicone in resin modification. For resin manufacturers, it upgrades along the path of "physical silicone blend → silanol-terminated copolymer → carbon-hydroxyl Si-C embedding", reducing humid-heat bleeding and gel risk while raising slip, water resistance, and long-term hand-feel premium.