Synthesis and applications of silicone oil–soluble fluoroalkyl end‐capped cooligomers

Fluoroalkyl end‐capped cooligomers containing polydimethylsiloxane and polyoxyethylene segments were prepared under very mild conditions by the cooligomerizations of fluoroalkanoyl peroxides with methacrylate monomers containing the corresponding segments and comonomers such as dimethylacrylamide and acryloylmorpholine. These obtained fluorinated cooligomers exhibited amphipathic characteristics and became soluble in water and common organic solvents. In particular interest, fluoroalkyl end‐capped cooligomers containing polyoxyethylene units were soluble not only in poly(methylphenylsiloxane) (silicone oil) but also in water, including common organic solvents except for hexane. Additionally, these fluorinated cooligomers were able to reduce the surface tension of water and m‐xylene quite effectively, to around 15 and 20 mN/m levels, respectively. In these fluorinated cooligomers, fluoroalkyl end‐capped acryloylmorpholine cooligomers containing polyoxyethylene segments were applicable as a novel emulsifying agent against water and silicone oil. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1467–1476, 2005     

Synthesis and properties of ultraviolet/moisture dual‐curable polysiloxane acrylates

Ultraviolet (UV)/moisture dual‐curable polysiloxane acrylates (PSAs) were prepared from N,N‐bis[3‐(triethoxysilyl)propyl]amine (G402) and ethoxylated trimethylolpropane triacrylate (EB160) through Michael addition. The obtained prepolymers were characterized by ¹H‐NMR and FTIR. The rheological behavior of the prepolymers exhibited the properties of a Bingham fluid and the apparent viscosity was directly correlated with molecular weight. The photocuring kinetics of PSA were studied using photo‐DSC and all the polymerization conversions were high. With increasing content of tertiary amine in the prepolymer, the photocuring rate in air increased as well. The moisture‐curing kinetics of the prepolymers was studied using FTIR. It was found that the curing mechanism may be described as the transforming of Si O C into Si O Si structure, which was consistent with the theoretical expectation. DSC and TGA were used to characterize the glass‐transition temperatures and the thermomechanical stability of the prepolymers. Measurements of physical properties showed excellent gloss, impact strength, and high electric resistance for both UV‐ and moisture‐cured films, but poor adhesion for UV‐cured films and lower hardness for moisture‐cured films. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 846–853, 2005     

Evaluation of the efficiency of silicone polyether additives as antifoams in crude oil

It is common for crude oil from wells to be accompanied by gas and water because of the presence of natural surfactants in the oil that stabilize the associated water. This causes foaming during processing in gas/oil separators because of the constant agitation and shear forces, which reduce the efficiency of the process and require chemical control by the addition of defoaming additives, or antifoams. In this work, we evaluated the chemical and physicochemical properties of commercial antifoam products based on silicone polyethers along with their efficiency in inhibiting foaming and water/oil (W/O) phase separation. The commercial surfactants were characterized by NMR spectroscopy, size exclusion chromatography, determination of solubility in different solvents, and measurement of the surface and interfacial tensions. A method to test the formation of foam in oil was used to mimic the operating conditions in gas/oil separators. Finally, tests were performed with the addition of aliquots of the additive solutions (30% p/v) in oil to evaluate their efficiency in breaking up the foam under different conditions. The results show that the most polar additive (SL2) was the most efficient in breaking up the foam. Additive SP1, which formed a heterogeneous phase in the oil, was also an efficient foam inhibitor and helped to separate these phases. The antifoam tests showed that these additives did not stabilize W/O emulsions, so they could be used in gravitational separation tanks in the field. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

氨基硅油的合成和表征及应用

介绍了氨基硅油的各种合成方法（如本体聚合法、乳液聚合法和硅氢化加成法等）以及它们各自的特点;并概述了氨基硅油的表征方法;重点介绍了氨基硅油在纤维（如织物、纸张和皮革）的整理、树脂（如聚氨酯、环氧树脂和丙烯酸树脂）改性、脱模剂、个人洗护用品（如洗发香波、牙膏）和抛光剂等方面的应用;最后展望了氨基硅油的应用前景。     

Synthesis and characterization of high‐performance epoxy resin based on disiloxane and 4,4′‐oxybis(benzoic acid) ester

Epoxy‐terminated siloxane‐contained resin (BCDS/OBBA‐ETS) with high tensile strength and lap shear strength as well as good thermal stability was synthesized and characterized by ¹H‐NMR and Fourier transform infrared spectroscopy. Carboxy‐capped disiloxane‐4,4′‐oxybis (benzoic acid) ester oligomer (BCDS/OBBA) was firstly prepared from the reaction between 1,3‐bis(chloromethyl)‐1,1,3,3‐tetramethyl‐disiloxane and 4,4′‐oxybis(benzoic acid) (OBBA) in N,N‐dimethylformamide in the presence of triethylamine. Then, the BCDS/OBBA oligomer was reacted with epichlorohydrin to obtain the title BCDS/OBBA‐ETS resin. Cured with liquid polyamide L‐651, or diethylenetriamine, the mechanical and thermal properties as well as the lap shear strength of the BCDS/OBBA‐ETS resin were evaluated. The results indicated that the BCDS/OBBA‐ETS resin exhibited good thermal stability below 200°C, and the glass transition temperature (T_g) was about 64°C after cured with L‐651. The tensile strength of same cured BCDS/OBBA‐ETS resin was 27.46 MPa with a stain at break of 42.11%, and the lap shear strength for bonding stainless steel was 18.59 MPa. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Impressive Rate Raise of the Hydrosilation Reaction Through UV‐Activation: Energy and Time Saving

Silicone materials are widely used in many fields such as electrical or food industries and their consumption is constantly growing. They are generally cured by vulcanization reaction for long time at high temperatures which requires high energy consumption. The possibility to achieve the polymerization of silicone rubbers by UV‐activation promotes the reduction of both time and temperature leading to an impressive energy saving. Indeed, this process is more than 30 times faster than the thermal one. Moreover, the properties of the two resulting materials are comparable, indicating that the low time of UV‐activated hydrosilation reaction is suitable for the formation of crosslinked silicone polymers.

     

Silicone elastomers for electronic applications. I. Analyses of the noncrosslinked fractions

In a study about silicone contamination on surfaces, crosslinked polydimethylsiloxanes have been examined focusing on the curing process and the noncrosslinked part in the bulk of the material. Curing was studied by following the development of gel as a function of curing time and temperature using Soxhlet extraction and differential scanning calorimetry (DSC) measurements. Gas chromatography–mass spectroscopy (GC‐MS), size exclusion chromatography (SEC), and thermogravimetric analysis (TGA) analyses gave information about the composition and size of the noncrosslinked fraction. The experiments demonstrate that the curing kinetics are of Arrhenius type with a strong temperature dependence. Interestingly, we find that 5–20% of the material does not undergo crosslinking reactions, although only 0–1% of the total sample mass is volatile at ambient temperature and pressure. It is likely that the volatile components mainly give rise to problems when they are confined to closed compartments or when they are in direct contact with a cold surface so that condensation on the surface occurs. Most likely, surface contamination originates from the nonvolatile fraction of the noncrosslinked portion of the material. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2073–2081, 2003     

Investigation of interactions between silicones and stratum corneum lipids

Ingredients of topically applied skin care formulations have not only positive effects on the appearance of human skin but can also disturb the Stratum corneum (SC) lipid barrier. In the present study, the influence of silicones (PDMS), as often used cosmetic ingredients, on the microstructure of SC lipids was investigated. For this purpose the interactions of four different PDMS with excised human SC were examined first using differential scanning calorimetry (DSC) and wide angle X-ray diffraction for physical characterization. Because the physical properties of human stratum corneum strongly depend on the lipid composition, showing inter-and intra-individual differences, the interactions with an in vitro model lipid system containing SC fatty acids were also studied, using polarized light microscopy, transmission electron microscopy, small angle X-ray diffraction and DSC. The results revealed that the investigated PDMS do not change either the microstructure of excised human SC or the biphasic lamellar/inverse hexagonal structure of the in vitro model. We concluded that PDMS will not cause any side-effects when topically applied and that our simplified in vitro model could be helpful for estimating interactions between cosmetic ingredients and other topically applied substances and the skin barrier at an early moment of formulation development.     

膨胀型硅丙乳液防火涂料

本文介绍了以硅丙乳液为成膜物 ,添加成炭剂、阻燃剂、发泡剂制成的膨胀型防火涂料的组成、生产方法、性能及特点     

Vinyl ester resin modified with silicone‐based additives: II. Flammability properties

Silicone‐based additives have been used as fire retardants for thermoplastics, presenting the advantages of improving processing and impact resistance of the polymers. In this work we used three different silicone‐based additives as modifiers of a thermoset based on a vinyl ester resin. The additives are fine powders made up of about 50 wt % ultra high molecular weight polydimethylsiloxane and 50 wt % silica. The differences between them are the functional groups inserted on the additives and the size and size distribution of the particles. The additives were dispersed in resin containing 35 wt % of styrene. For curing the mixture a conventional catalyst and initiator were used and the reaction was carried out in two ways, differing in the curing temperature, the post curing temperature, and the time, and in the addition of dimethylaniline (DMA) as a promoter of the polyaddition reaction. The samples were characterized by thermogravimetric analyses and swelling experiments. The fire retardances of the samples were evaluated by the determination of the flash‐ignition, self‐ignition, and pyrolysis temperatures (ASTM D1919–91a), and of the oxygen index (ASTM D‐2863–91). The results obtained showed that the silicone‐based additives and the methods used in the preparation of the modified resin influence the flash‐ignition, self‐ignition, and pyrolysis temperatures, but not the oxygen index. Samples cured by different methods present different network characteristics, which influence their thermal decomposition. The volatile species produced by thermal decomposition may be a combination of inert and active species. The network structure may influence only the inert fraction of the volatiles, not the combustibles. These volatile inert species (smoke‐black, water vapor, carbon dioxide, etc.) probably dilute the combustibles in the solid and in the gaseous phase, increasing the flash‐ignition temperature of the samples. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 644–649, 2006