Polysiloxane polyols

The very low glass transition temperature (Tg) of polysiloxane chains (Tg = -123 °C) is a very attractive property for using these kinds of polymeric chains to build an oligo-polyol structure with terminal hydroxyl groups [1]. The resulting structure called a polysiloxane polyol gives, after reaction with diisocyanates, polyurethane (PU) elastomers which conserve their high elasticity at very low temperatures [1]. 

The synthesis of some experimental siloxane polyols is based on several reactions developed in two steps  

Step I synthesis of a polysiloxane chain of molecular weight (MW) of 1000-3000 daltons, having terminal -Si-H bonds, by using classic reactions (reactions 11.1 and 11.2) [2-6]. These kinds of polysiloxanes with terminal -Si-H bonds are available commercially. 

Step II The addition of the -SiH group to a compound having a double bond and a hydroxyl group (allyl alcohol or allyl alcohol based polyethers). The reaction is catalysed 

Reaction 11.4 is used to decrease the unsaturation of polyether polyols simultaneously with the functionality increase. Thus, by introducing a polyether polyol with high unsaturation (0.07-0.09 mequiv/g), a low molecular weight polysiloxane compound, having 2-3 Si-H groups/mol, together with a platinum catalyst, the polyether monol present in the polyether (in fact allyl ether based polyethers) is added to the polysiloxane compound and the monol is transformed into a diol or into a triol (reaction 11.5). 

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A second method for the synthesis of polysiloxane polyols is the equilibration of cyclic polydimethyl siloxanes with a compound of the following structure (11.7) [6, 7] ... 

In Chapter 3, the chemistry and technology of the most important oligo-polyols used for elastic polyurethanes fabrication, in fact high MW oligomers (2000-12000 daltons) with terminal hydroxyl groups and low functionality (2-4 hydroxyl groups/mol) were discussed. Polyalkylene oxide polyols (homopolymers of PO or copolymers PO - EO, random or block copolymers), polytetrahydrofuran polyols, filled polyols (graft poly ether polyols, poly Harnstoff dispersion - polyurea dispersions (PHD) and polyisocyanate poly addition (PIPA) polyols), polybutadiene polyols and polysiloxane polyols were all discussed. The elastic polyurethanes represent around 72% of the total polyurethanes produced worldwide. 

Polyether-polyester polyol hybrids, 25 472 Polyetherimide-polysiloxane block copolymers, 24 698, 704, 708... 

Polyetherimide-polysiloxane multiblock copolymers, 24 716 Polyetherimides (PEI), 10 217—218 Polyether impression materials, 8 332-333 Poly(ether ketones) (PEK), 10 197-199 Polyether polyols, 25 455-456,464,468t, 470 propylene oxide polymerization to, 20 793-794, 812 Poly ethers, 12 663... 

Polymerization Solvent. Sulfolane can be used alone or in combination with a cosolvent as a polymerization solvent for polyureas, polysulfones, polysiloxanes, polyether polyols, polybenzimidazoles, polyphenylene ethers, poly(l,4-benzamide) (poly(imino-l,4-phenylenecarbonyl)), silylated poly(amides), poly(arylene ether ketones), polythioamides, and poly(vinylnaphthalene/fumaronitrile) initiated by laser (134—144). Advantages of using sulfolane as a polymerization solvent include increased polymerization rate, ease of polymer purification, better solubilizing characteristics, and improved thermal stability. The increased polymerization rate has been attributed not only to an increase in the reaction temperature because of the higher boiling point of sulfolane, but also to a decrease in the activation energy of polymerization as a result of the contribution from the sulfonic group of the solvent. 

Ho et al (1996) examined polyol or polysiloxane thermoplastic polyurethanes (TPUs) as modifiers in cresol-formaldehye novolac epoxy resins cured with phenolic novolac resin for computer-chip encapsulation. A stable sea-island dispersion of TPU particles was achieved by the epoxy ring-opening with isocyanate groups of the urethane prepolymer to form an oxazolidone. The flexural modulus was reduced by addition of TPU and also the Tg was increased due to the rigid oxazolidone structure. Mayadunne et al (1999) extended this work to a series of phenol- and naphthol-based aralkyl epoxy resins. 

Weighed amounts of bio-polyols, catalyst (Stannous 2-ethyl hexanoate), surfaetant (polyether-modified polysiloxane), and blowing reagent (distilled water) were mixed well in a paper cup. A prescribed amoimt of MDI was added to the mixture, which was then stirred with a high-speed stirrer (5,000 rpm) for 15 s. After stirring, the mixture was poured immediately into another paper cup, and the foam was allowed to rise and set at ambient conditions (22 °C). Finally, the foam samples were cured at room temperature for 24 h before any analysis can be conducted. The formulations of the prepared foams are shown in Table 2. 

Chem. Descrip. Mixf. of special polyols, emulsifiers, and polysiloxane Uses Air release agenf and defoamer for general purpose high-solids and industrial coatings (all ds, epoxies, acrylics, waterborne architectural), printing inks, adhesives, latex applies. 

Chem. Descrip. Mixt. ot specially modified polyols and polysiloxane adduct... 

Use Level 1-2% (on polyol component, added to hardener component) Storage Store in a cool, dry place 2 yr max. shelf life when kept in the original, unopened container EFKA -3883 [EFKAAdditives BVj Chem. Descrip. Polysiloxane-based... 

The best separations of polyols have been achieved on mixed phase packings, which combine the high resolving capacity of the polar phase with the stability of the nonpolar phase. Reported stationary phases are 2-10% EGSS-X (ethylene glycol succinate copolymerized with dimethyl polysiloxane) or ECNSS-M (ethylene glycol succinate copolymerized with cyano-ethyl methyl polysiloxane) on uncoated adsorbent from diatomite, acid washed, and dimethylchlorosi-lane-treated or uncoated adsorbent from diatomite acid-washed and silanized, 3% XE-60 (poly(methyl cyanopropyl siloxane)) on uncoated adsorbent from diatomite acid-washed and silanized, GP 3% SP-2340 (poly(dicyanopropyl siloxane)) on diatomite support and many other combinations. 

Cemeton Pluracol Polyol Poly (Dimethylsiloxane) Polypropylene Glycol Dimethyl Polysiloxane... 

Hydroxyl-containing silicon material with the hydroxyl groups attached directly to a silicon atom are combined together to react to form silanol-functionalised urethane prepolymers that can cure at ambient temperatures in the presence of moisture to form polysiloxane polyurethanes. For instance, physical blends of a polypropyleneoxide polyol intermediates and an organic-silicone block copolymer-based polyol intermediates have been prepared to improve elongation and reduced... 

Chem. Descrip. Polysiloxane-polyether block copolymer Uses Foam stabilizer and emulsifier for rigid PU and polyisocyanurate foams with max. demand on flow properties esp. for refrigeration and pipe insulation Properties Cl, vise, liq, sol. in common rigid foam polyols and resin preblends dens. 1,055 0,01 g/cc vise. 750 170 mPa-s solid, pt. < -8 C hyd. no. 100 10 cloud pt. 70 3 C (4% aq.) pH 6.5 1.5 (4% aq.)... 

In this research, a novel semi-interpenetrating networks electrolyte has been developed by a solvent-free reactive process. A flexible amorphous polyether modified polysiloxane is incorporated in polyurethane and form semi-interpenetrating network (IPN) structure by in-situ polymerization of polyurethane with the presence of PEMPS and salts. The monomer of polyurethane, polyol, functions as the common solvent to dissolve the salts so no additional volatile solvent is needed in this reactive process. The addition of PEMPS is expected to improve the ionic conductivity of polyurethane due to its high ionic conductivity and the decrease in crystalinity of soft segment of polyurethane as well as the generation of the high conductive interface. 

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