Methyl Hydrosiloxane Research Articles

Study of Hydrophobic Nature of Fullerene-Based Poly (Methyl Hydro Siloxane) and Polyacrylonitrile Interpenetrating Polymer Network

Study of Hydrophobic Nature of Fullerene-Based Poly (Methyl Hydro Siloxane) and Polyacrylonitrile Interpenetrating Polymer Network

Hydrophobic and Oleophilic Filter Paper for Oil/Water Separation

The separation of oil from water is significance for environmental de-pollution application. To obtain selectivity of liquid, filter papers were coated to bear highly hydrophobic and oleophilic functionality that can allow only oils to pass through them. The coating solutions were prepared by mixing poly(methylhydro siloxane, PMHS) and fumed silica at various proportions. To determine an optimum coating condition, properties of the treated filter papers were investigated by measuring water contact angle and surface free energy, examining surface morphology and testing for selective removal of diesel oil from water. The optimum coating solution was at the PMHS:fumed silica weight ratio of 1.25:1.00. The treated filter paper exhibited high hydrophobicity with water contact angle of 142.80 ± 0.36 degrees and surface free energy of 0.78 mJ/m2. In addition, it exhibited high selective removal of diesel oil from water with oil absorption capacity of 2.3 g/g.

Fabrication of localised aluminium foam by a novel polymeric blowing agent

Closed cell aluminium foams are highly pursued, due to their unique combination of properties. However, the current applicability of the aluminium foams is limited due to issues like high costs, density-gradient and brittleness of the cell walls, which are either related to use of metallic hydride as blowing agent or liquid-state processing. To address these issues, this study presents a first attempt to use polymer as a blowing agent to foam an aluminium alloy. A polymer is Poly (methyl hydro siloxane) was dispersed into an Al2024 sheet of 6 mm by Friction Stir Processing, in a localised region. This processed sample was pyrolysed at temperatures between solidus and liquidus (500–640 °C) of the alloy and at various durations (5–60 min) to foam the localised precursor. The density of resulting foams was measured by the Archemidies method and the resulting pore structures were characterised by Scanning Electron Microscopy (SEM) and micro X-ray Computed Tomography (CT). The results show that by as pyrolysis temperature increases relative density reaches a minimum of 0.65 at 560 °C. Beyond 590 °C, relative density increased from the optimum due to escape of foaming gasses. With increasing pyrolysis temperature, the pore size increased from few microns to several hundred microns. Further, quasi-static compression test was done on as processed, solutionized and aged foams. Due to increased strain hardening in aged samples energy absorbed during compression increased by 80% in the plateau region. Hence, polymeric a blowing agent can be used to synthesize heat-treatable foams with controllable absorption energy.

Experimental Study of Miscible Thickened Natural Gas Injection for Enhanced Oil Recovery

Hydrocarbon-miscible gas flooding typically involves injection of an associated gas (AG) mixture containing mainly methane (CH4) enriched with light hydrocarbon fractions and possibly acid gases. The AG mixture has been recognized as an excellent candidate for miscible gas injection (MGI). However, in general, the viscosity of the AG at reservoir conditions is significantly lower than that of crude oil leading to an unfavorable mobility ratio and low volumetric sweep efficiency during flooding. This study assesses the suitability of a library of commercially available polymers to thicken AG as a means of mobility control. The focus of the study is on the Field A located in the Harweel cluster in southern Oman. First, soluble polymeric thickeners for an AG mixture (CH4 60%, C2H6 9%, C3H8 6%, and CO2 25%) were identified using a parallel gravimetric extraction technique combined with cloud point measurements. Then, the viscosity of the identified soluble polymeric candidates in AG mixture was measured in a capillary viscometer at reservoir conditions. Three polymers were found to be completely or partially soluble in the AG mixture at 377 K and 55 MPa including poly(1-decene) (P-1-D), poly(methyl hydro siloxane) (PMHS), and poly(dimethylsiloxane) (PDMS). P-1-D found to be an effective thickener in AG mixture under conditions relevant to Field A, i.e., high temperatures and pressures. The polymer is soluble in the concentration range of 1.5–9 wt%. The viscosity of the P-1-D- thickened AG mixture increased by 2.2–7.4 times greater than AG mixture viscosity at 358–377 K. Furthermore, reservoir condition core flooding experiments were performed to examine the effectiveness of P-1-D-thickened AG gas mixture flooding to enhance oil recovery. The thickened-AG mixture flooding resulted in delayed gas breakthrough and subsequently 10–12% additional oil recovery.

Mechanochemical modification of kaolin surfaces for immobilization and delivery of pesticides in alginate-chitosan composite beads

The surface modification with poly(methyl hydrosiloxane) (PMHS) using a grinding method as a pesticide carrier had been successfully achieved. The characteristics of the modified kaolin were represented by Fourier transform infrared, X-Ray diffraction, BET specific surface area measurements, laser particle size analysis, transmission electron microscopy and contact angle measurement. Subsequently, immobilization of acetamiprid onto clay’s surface was carried out by means of freeze-drying technology. And the drug-loaded clays were encapsulated in alginate-chitosan composite beads by extrusion into calcium chloride solution. The composite beads showed regularly spherical shapes and uniform sizes with diameters of 1.44 ± 0.24–1.75 ± 0.19 mm. The immobilization and release of acetamiprid were carried out to examine the effect of the modified kaolin on the properties of the composite bead. The results showed that the intensive force of superfine pulverization during the grinding process was effective to increase the specific surface areas of the modified kaolin with particle size reduction. The modified kaolins as promising carrier materials had improved the drug loading rate and encapsulation efficiency from 4.15 and 42.01 % for alginate-chitosan composite beads to 6.02 and 82.95 %, which were higher than 4.33 and 54.29 % for SA-CS-kaolin composite beads, respectively. The controlled-release formulation containing the modified kaolin had shown slow and sustained release properties to promote the efficient use of organic pesticide to reduce pollution effect on the environment.

Collision‐induced dissociation of synthetic polymers containing hydride groups: the case of poly(methylhydrosiloxane) homopolymers and poly(methylhydrosiloxane)‐co‐(dimethylsiloxane) copolymers

When substituting one methyl moiety by a hydrogen atom in each end-group of a trimethylsilyl-terminated poly(dimethylsiloxane) (PDMS), dissociation reactions of oligomers adducted with ammonium were observed to proceed at a much higher rate, evidencing the high reactivity of hydride groups. Polymeric molecules containing methylhydrosiloxane (MHS) units could thus be expected to exhibit a different tandem mass spectrometric (MS/MS) behavior from PDMS. Trimethylsilyl-terminated PMHS and trimethylsilyl-terminated poly(MHS)-co-(DMS) were electrosprayed in the gas phase either as ammonium adducts or lithium adducts. Product ions generated upon collision-induced dissociation (CID) were accurately mass measured in an orthogonal acceleration time-of-flight mass analyzer. In contrast to PDMS adducted with lithium, useful structural features could be obtained from product ions generated upon CID of lithium adducts of PMHS. The presence of multiple hydride groups in PMHS induced numerous rearrangements when activating ammonium adducts of these oligomers. MS/MS reactions observed for cationic adducts of MHS-DMS co-oligomers were clearly a combination of major dissociation routes established for the corresponding homopolymers. However, the concerted loss of H(2) and ammonia typically observed from ammonium adducts of PMHS was always shown to generate a quite abundant product ion even from co-oligomers enriched with DMS units. The high reactivity of hydride moieties, previously evidenced when these groups were at the end of PDMS chains, is also at work in PMHS, where each monomer contains a Si-H function. The presence of these hydride groups would increase the nucleophilic character of the oxygen atoms, favoring a tight bonding of lithium, and hence allowing in-chain cleavages to occur. In PMHS ammonium adducts, the particular reactivity of hydride moieties was illustrated by multiple hydride transfers but also by a dehydrogenation reaction systematically observed to proceed, together with the loss of ammonia, from all precursor ions. This latter reaction remained a very competitive process even from MHS/DMS co-oligomers with a low relative number of MHS units.

Phase transition behavior of silicone based liquid crystalline polymers

AbstractPhase transition behavior of silicone based liquid crystalline (LC) polymers with variable isotropic transition temperatures (Ti), synthesized from poly(methyl hydrosiloxane), 10-undecenoic acid based crosslinking agent and cholesterol based side chain mesogen, was studied by differential scanning calorimetry (DSC), polarizing optical microscopy (POM), and X-ray diffraction (XRD) measurements. The chemical structure of the mesogenic monomer and the LC polymers were confirmed by Fourier transform infra-red (FT-IR) spectroscopy and 1HNMR spectroscopy. DSC studies showed that the glass transition temperatures (Tg) and Ti of the LC polymers decreased with increasing proportion of mesogenic crosslinking agent at its low proportion and at its higher proportion Ti disappeared completely indicating that the polymeric chains had less chance to orient in the network structure. The results were consistent with the XRD and POM studies.

A Systematic Approach To Decipher the Microstructure of Methyl Hydrosiloxane Copolymers and Its Impact on Their Reactivity Trends

A thorough comprehensive microstructure analysis of poly(dimethylsiloxane-co-hydromethylsiloxane) copolymers (PDMS-co-PHMS) was achieved using high resolution two-dimensional NMR (29Si/1H) techniques viz. heteronuclear multiple bond coherence (HMBC) and total correlation spectroscopy (TOCSY) in conjunction with 1D 29Si and 1H NMR spectroscopy. A rigorous analysis of the splitting patterns along 29Si NMR axes of hydromethylsiloxane, [−OSi(H)Me−]/“DH” units and dimethylsiloxane, [−OSi(Me)2−]/“D”units in PDMS-co-PHMS revealed sensitivity of their chemical shifts to variation in copolymer composition. Interestingly, 1H NMR signals of hydromethylsiloxane, [−OSi(H)Me−] units showed an additional sensitivity to tacticity (meso, racemic) effects. With aid of 2D HMBC (29Si//1H) NMR spectra, we could resolve unambiguously the highly complex and overlapped −Si–CH3 region in 1H NMR spectrum into the respective compositionally and configurationally sensitive D/DH triads. Further, the reactivity trend of Si–H groups was studied by hydrosilylation reaction of these copolymers (PDMS-co-PHMS) with model molecules like α-methylstyrene and 1-octene. An intriguing trend toward preference for racemic (r) orientation of Si–H on PDMS-co-PHMS backbone during hydrosilylation reactions resulting in syndiotactically enriched products was observed. This observation signifies a crucial fact of possible scientific interest that the Si–H dyads with the racemic configurations were more available for complexation with Pt catalyst during hydrosilylation than the meso dyads. The authors attribute these not-so-obvious experimental observations to the role of conformation of the polymeric chains. The interpretation of these peculiar findings and the reactivity patterns observed has been documented in this article.

Analytical application of poly{methyl[3-(2-hydroxy-3,4-difluoro)phenyl]propyl siloxane} as a QCM coating for DMMP detection

A new material—poly{methyl[3-(2-hydroxy-3,4-difluoro)phenyl]propyl siloxane}(PMDFPS) sensitive to toxic organophosphate vapor was synthesized with 2,3-difluorophenol, allyl bromide and poly (methyl hydrosiloxane) as raw materials, via O-alkylation, Claisen rearrange reaction and hydrosilylation reaction. This novel material was then coated on a quartz crystal microbalance (QCM) to investigate its gas sensitive properties to the nerve agent simulant dimethyl methylphosphonate (DMMP) vapor, as well as known interfering vapors. When tested with competing vapors, the sensor was more than 10 times sensitive to DMMP than to other interfering vapors. Thus, high selectivity of poly{methyl[3-(2-hydroxy-3,4-difluoro)phenyl]propyl siloxane} to DMMP was demonstrated. The poly{methyl[3-(2-hydroxy-3,4-difluoro)phenyl]propyl siloxane}-QCM sensor responded linearly to DMMP vapor with a slope of 14 Hz/ppm in the 1–50 ppm range with a detection limit of 0.21 ppm (S/N = 3).

Ionic conductivity and morphology of semi‐interpenetrating‐type polymer electrolyte entrapping poly(siloxane‐g‐allyl cyanide)

AbstractWe prepared a semi‐IPN (interpenetrating network)‐type solid polymer electrolyte (SPE) using poly (ethylene glycol)dimethacrylate (PEGDMA) as a polymer matrix containing a monocomb‐type poly(siloxane‐g‐allyl cyanide) and poly(ethylene glycol)dimethylether (PEGDME) for the lithium secondary battery. The poly(siloxane‐g‐allyl cyanide)s were prepared by a hydrosilation reaction of poly (methyl hydrosiloxane) with allyl cyanide and characterized by 1H NMR and FTIR. The semi‐IPN‐type electrolyte was prepared by thermal curing, and conductivities of samples were measured by impedance spectroscopy using an indium tin oxide (ITO) electrode. The ionic conductivity of the semi‐IPN‐polymer electrolyte was about 1.05 × 10−5 S cm−1 with 60 wt % of the poly(siloxane‐g‐allyl cyanide) and 6.96 × 10−4 S cm−1 with 50 wt % of the PEGDME and 10 wt % of the poly(siloxane‐g‐allyl cyanide) at 30°C. The SEM morphology of the cross section of the semi‐IPN‐polymer electrolyte film was changed from discontinuous network to continuous network as increasing the PEGDME content and decreasing the poly(siloxane‐g‐allyl cyanide) content. The mechanical stability was also enhanced when increasing the PEGDME content. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Two new siloxanic proton-conducting membranes: Part I. Synthesis and structural characterization

The development of stable polymer electrolytes having good proton conductivity, low cost and operating at medium temperatures represent a crucial step in the evolution of polymer electrolyte fuel cells. We describe two new siloxanic proton-conducting membranes that were synthesized through a two-stage protocol. In the first stage, a poly(methyl hydrosiloxane) precursor ( P) bearing siloxane side chains with sulfonic acid groups was prepared. In the second step, the hydrolysis of pristine precursor or its derivative obtained by grafting siloxane chains on P yielded two types of membranes with the formulas {Si(CH 3) 3O[Si(CH 3)HO] 21.26 [Si(CH 3)((CH 2) 3SO 3H)O] 1.8 [Si(CH 3)((CH 2) 3Si(CH 3) 2O ) O] 14 Si(CH 3) 3} n ( A) and {Si(CH 3) 3O[Si(CH 3)HO] 21.26 [Si(CH 3)((CH 2) 3SO 3H)O] 1.8 [Si(CH 3)((CH 2) 3(Si(CH 3) 2O ) w ) O] v [Si(CH 3)((CH 2) 3Si(CH 3) 2O–) O] 14 − v Si(CH 3) 3} n ( B), with w = 20.31. Polymer membranes of A and B were prepared by means of a hot-pressing process at 80 °C and 10 t/cm 2. Scanning electron microscopy showed that A and B are rubbery materials with rough and transparent surfaces. Thermogravimetric investigations performed under air atmosphere disclosed that A and B are thermally stable up to at least 198 °C. DSC measurements yielded T g(s) of −44 and −60 °C for A and B, respectively. The polymers exhibit ionic exchange capacities of 0.33 ( A) and 0.15 meq/g ( B). FT-IR and FT-Raman investigations revealed that the polymers consist of reticulated siloxane networks with pendant silicone chains having sulfonic acid groups.

Synthesis and characterization of ultraviolet‐curable fluorinated polydimethylsiloxanes as ultraviolet‐transparent coatings for optical fiber gratings

AbstractSynthesis of photocrosslinkable fluorinated polydimethylsiloxane (PDMS) was carried out through the direct hydrosilylation of allyl 2‐(perfluorohexyl)ethyl ether with copoly(dimethyl methyl hydro siloxane). The hydrosilylation of the fluorinated allyl ether allowed the introduction of fluorinated groups onto the polysiloxane backbone. Then, a second hydrosilylation of allyl methacrylate led to PDMS bearing both fluorinated and photocrosslinkable groups. The ratio between fluorinated groups and allyl methacrylate groups allowed us to tune the refractive index of the resin without changing thermal properties. Formulations containing fluorinated PDMS were ultraviolet‐cured, and their ultraviolet transparency and Yttrium Aluminium Garnet (YAG) laser resistance were investigated. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2021–2026, 2003

Compatibilization of side‐chain, thermotropic, liquid‐crystalline ionomers to blends of polyamide‐1010 and polypropylene

AbstractA novel side‐chain, liquid‐crystalline ionomer (SLCI) with a poly(methyl hydrosiloxane) main chain and side chains containing sulfonic acid groups was used in blends of polyamide‐1010 (PA1010) and polypropylene (PP) as a compatibilizer. The morphological structure, thermal behavior, and liquid‐crystalline properties of the blends were investigated by Fourier transform infrared, differential scanning calorimetry, thermogravimetric analysis, and scanning electron microscopy. The morphological structure of the interface of the blends containing SLCI was improved with respect to the blend without SLCI. The compatibilization effect of greater than 8 wt % SLCI for the two phases, PA1010 and PP, was better than the effects of other SLCI contents in the blends. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2749–2754, 2002; DOI 10.1002/app.10179

Copper diffusion in organic polymer resists and inter-level dielectrics

In future generation microelectronic devices, it is anticipated that back end of the line processing may incorporate interconnects composed of Cu metal, and inter-level dielectrics composed of organic polymers. In this study, we examined a number of commercially available and new NRL synthesized organic polymer systems towards Cu metal incorporation in the film during application. All the polyimides examined transported Cu, in large part due to the ability of the solvent, 1-methyl-2-pyrrolidinone (NMP), to dissolve Cu. We report examples where the solvent is largely responsible for Cu incorporation into the polymer film, and examples where the polymer and not the solvent is responsible for Cu transport into the film polymethyl methacrylate. Three preparations examined in this study, polystyrene, Teflon AF, and 1,3,5-tris (2-allyloxy-hexafluoro-2-propyl) benzene/poly methyl hydrosiloxane, were found to resist Cu diffusion.

Synthesis, Characterization, and Mesomorphic Behavior of Terminally Carboxyl Oligo(ethylene oxide) Monomethyl Ethers-Substituted Side Chain Liquid Crystalline Copolysiloxane Polymers

Smectic copolysiloxane polymers can be obtained by co-grafting two smectic monomers onto poly(methyl hydrosiloxane). The ratio of the monomers in the copolymers is characterized by 1H NMR. The mesomorphic properties of copolysiloxane polymers are studied by optical microscopy, DSC, and X-ray diffraction. The effects of the monomer ratio on the liquid crystalline texture, isotropization temperature, enthalpy changes of liquid crystal/isotropic transltion, and layer spacing (d1) of these polymers are discussed.

Hydrosilylation of Mesogens Having Carbon-Carbon Double Bonds with Poly(methyl hydrosiloxane)s

Abstract Liquid-crystalline compounds having carbon—carbon double bonds were synthesized and subjected to hydrosilylation using poly(hydrosiloxane)s as silylating agents and hexachloroplatinic acid as a catalyst. Even though the silylating agents were polymeric and the mesogenic compounds carried bulky groups as their side chains, the presence of a spacer (polymethylene chain) diminished the steric hindrance and the reaction was possible. Among the mesogens 1-(4′-allyloxybenzoyloxy)-4-(4″-methoxybenzoyloxy)phenylene is a new compound, and its synthesis is described in detail. The final products were side-chain-type liquid-crystalline polymers, that is, mesogenic group-grafted poly(siloxane)s, and a few of their liquid-crystalline properties are also elucidated.