In organosilicon and organic polymer modification, side-chain hydride silicone oils scatter Si–H along the backbone; platinum-catalyzed hydrosilylation causes multi-point grafting and unpredictable crosslinking, making end-reactive linear products hard to control. Common dimethyl silicone oil has no reactive site and only serves as inert diluent. Low-hydrogen water-repellent fluids focus on filming rather than stoichiometric end reactivity, thus cannot tune addition-cure rubber chain length or heat-cure crosslink precisely. Polymer resin modification with improper active siloxane segments often suffers poor compatibility, over-crosslinking or hardness rebound. For specifications demanding "terminal high activity, graded molecular weight, calculable Si–H equivalence, optional hydrophobing", a strictly controlled hydride-terminated polydimethylsiloxane places reaction-site control and product-structure customization at one intermediate node. Addressing this, Anhui IOTA Silicone Oil Co., Ltd. launches Hydride-Terminated Silicone Oil IOTA-616. Characterized by "odorless transparent liquid; chemical name hydride-terminated silicone oil; alias hydrogen-terminated polydimethylsiloxane; CAS 70900-21-9; colorless transparent; main content ≥99%; five grades—viscosity 25℃ 2-3mPa·s, MW 500-600, H%0.5, density 0.9, RI 1.395; 100mPa·s, MW6000, H0.04%, density0.97, RI1.403; 500mPa·s, MW17200, H0.01%, density0.97, RI1.403; 1000mPa·s, MW28000, H0.007%, density0.97, RI1.403; 10000mPa·s, MW62700, H0.003%, density0.97, RI1.403; terminal active Si–H higher activity than side-hydride oils, key reactive intermediate; uses: hydrosilylation to end-reactive linear modified silicones, block copolymerization intermediate, chain extender for addition LSR and crosslinker for addition HCR improving elongation/toughness/lower hardness, starter for plastic/resin modification, hydrophobing/moisture resistance similar to related hydride silicone categories; 200L plastic/iron drum 190KG net; storage no open flame, ventilated dry, no acid/base, -45℃ to 45℃, transport rain/sun protected, hazardous storage/transport; brand IOTA", backed by "bis-terminal Si–H + five MW grades + high-purity stoichiometric", it serves as a bis-terminal reactive intermediate. System Positioning: End-Hydride Oil Among Hydride Siloxane Intermediates Within hydride siloxane families, IOTA-616 is bis-terminal hydride PDMS, distinct from side-chain hydride oils (Si–H scattered, good for waterproof filming and dense crosslink but poor end-pointing), end-side mixed hydride oils (multiple site types, hard structure prediction), dimethyl silicone oil (no Si–H, inert), and vinyl silicone oil (reacts with hydride but provides no hydrogen). IOTA-616 offers only two terminal hydrides per molecule with five MW grades to tune total hydrogen equivalent, positioning as a directional intermediate for "hydrosilylation modification, block copolymerization, LSR chain extension/HCR crosslink, resin modification, hydrophobing", rather than a pure water repellent or mono-end capper. Molecular Architecture: Bis H–SiMe₂O + Dimethylsiloxane Backbone + Five Chain Lengths + Decreasing Equivalent IOTA-616 structure H–[Si(CH₃)₂O]ₙ–H places one Si–H on each terminal silicon with low steric hindrance; terminal hydrides contact platinum centers more readily than backbone hydrides, giving high selectivity. Low-viscosity 2-3mPa·s/MW500-600/H0.5% gives maximum terminal density for end-grafting polyether, epoxy or alpha-olefin; 100mPa·s/MW6000/H0.04% suits block copolymerization and moderate chain extension; 500/1000/10000mPa·s grades with H 0.01% to 0.003% and MW 17200-62700 introduce long flexible siloxane blocks with low hydrogen equivalent for toughening; density rises from 0.90 to 0.97 and RI from 1.395 to 1.403, with high-viscosity grades at 1.403 for consistent optical/batch appearance; main content ≥99% reduces impurities interfering with platinum catalysis. Performance Leap: From "Side-Chain Random Crosslink, Hard Equivalence" to "Bis-Terminal Fixed Sites, Graded Controllable" With IOTA-616, synthesis and vulcanization improve jointly: directed addition—two terminal Si–H sites react with terminal vinyl/allyl polymers near 1:1 Si–H/alkene equivalence, avoiding random multi-point crosslink; linear modification—low/MW100 grades yield bis-end polyether/epoxy/alkyl silicones for softening, foam stabilization and surfactancy; block copolymerization—bifunctional bridge joins polyether/polyester/polyolefin with balanced weather flexibility; silicone rubber—low-MW grade extends chains and widens crosslink spacing in addition LSR to raise elongation and toughness while lowering hardness; mid/high-MW grades supplement addition HCR crosslink network without marked hardening; hydrophobing—terminal hydride can further crosslink or, like related hydride categories, form hydrophobic moisture-resistant layers for end-use protection. Application Penetration: From Modified Silicone to LSR, Blocks and Resin Protection IOTA-616 covers five core scenarios. End-reactive linear silicone synthesis: low-visc/100 grades hydrosilylate with polyether, epoxy, alpha-olefin to bis-functional oils; trial by target functionality. Block copolymerization: bis-hydride with diene monomers builds organic-silicone blocks—emphasizing flexibility/weather balance; trial by block MW. Addition LSR chain extension: low-MW grade improves elongation/toughness/lower hardness; trial by base vinyl content. Addition HCR crosslinking: mid/high-visc grades tune network and fracture mechanics; trial by curing system. Plastic resin modification and hydrophobing: starter for polymer modification, or substrate moisture resistance similar to hydride silicone categories. ⚠️ Taboo: no open flame, no acid/base, ventilated dry, -45℃ to 45℃; transport rain/sun protected, hazardous storage/transport; in hydrosilylation avoid water, alcohols, strong acid/base and sulfur/phosphorus/nitrogen/heavy-metal impurities that may inhibit platinum. IOTA Technical Guide: Select by MW, Dose by Si-H Equivalent, Hazardous Storage IOTA-616 is a colorless transparent liquid in 200L plastic/iron drums, 190KG net. For hydrosilylation, calculate Si–H equivalents from the selected grade H%, feed near-equivalent terminal alkene/allyl, and react under suitable platinum catalysis; for chain extension/crosslink, choose grade by LSR or HCR vinyl content and target hardness/elongation with trial. Storage: no open flame, ventilated dry, no acid/base, -45℃ to 45℃; transport rain/sun protected, hazardous storage and transport. Industry Insight: End-hydride intermediate selection is not the higher hydrogen the better, but using terminal sites for selectivity, MW grades for chain length and total hydrogen equivalent, main purity for platinum stability, and downstream target for chain-extender or crosslinker role. For modified-silicone, silicone-rubber and resin engineers, IOTA-616 uses one CAS 70900-21-9, ≥99% hydride-terminated PDMS with five grades 2-10000mPa·s across linear modification, block copolymerization, liquid/solid silicone rubber and moisture protection, taking bis-terminal activity, calculable equivalence and graded toughening as batch-checkable anchors, securing designable routes and reproducible performance.