Densely crosslinked polycarbosiloxanes. II: Thermal and mechanical properties

The thermal and mechanical properties of two densely crosslinked polycarbosiloxane systems were investigated in relation to the molecular structure. The networks were prepared from functional branched prepolymers and crosslinked via a hydrosilylation curing reaction. The prepolymers having only vinyl functionalities (poly[phenylmethylvinyl]siloxanes) were crosslinked by using crosslinking agents with reactive silicon–hydrogen groups. In prepolymers having both silicon–vinyl and silicon–hydrogen groups (poly[phenylmethylvinylhydro)]siloxanes crosslinking took place intermolecularly. The thermal and mechanical properties of the polymer networks were found to be dependent on the phenyl  Si O_3/2 (branches) content in the prepolymer, the number of elastically effective crosslinks, the elastically effective network chain density and molecular weight between crosslinks, length of the chain segments introduced by the hydrosilylation crosslinking reaction, and the number of dangling ends. As a consequence of the dense crosslinking, the mechanical properties were also strongly dependent on the glass transition temperature. A tough–brittle transition was observed around the glass transition temperature of the polymer networks. The properties of the poly(phenylmethylvinylhydro)siloxane networks were found to be superior to those of the poly(phenylmethylvinyl)siloxane networks. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 1311–1331, 1997     

Poly(phenylhydrosilane): Base-developable polysilane resist

Poly(phenylhydrosilane) becomes soluble in a 2.38% tetramethylammoniumhydroxide aqueous solution after exposure to UV light. This is the first report that the polysilanes not bearing acidic groups can be developed with dilute basic aqueous solutions. Addition of 3,3′,4,4′-tetra(t-butylperoxycarbonyl)benzophenone increases the resist sensitivity. The reaction mechanism is as follows: PS1 photodecomposes to form silyl compounds having SiOH groups, which become soluble in an aqueous base solution, because these silane compounds bearing SiOHs are acidic. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2355–2364, 1997     

Permeation and separation of benzene/cyclohexane mixtures through liquid-crystalline polymer membranes

The side-chain liquid-crystalline polymer (LCP) was synthesized by the addition of the mesogenic monomer to poly(methylsiloxane) with Pt catalyst. When the benzene/cyclohexane mixtures were permeated through the LCP membranes by pervaporation at various temperatures, the permeation rate increased with increasing benzene concentration in the feed solution and permeation temperature. Though the LCP membranes exhibited a benzene permselectivity, a mechanism of the permeation and separation for the benzene/cyclohexane mixtures was different in the glassy, liquid-crystalline and isotropic state of the LCP membranes. These results suggested that the permselectivity was fairly influenced by the change of the LCP membrane structure, that is, a state transformation. It was found that a balance of the orientation of mesogenic groups and flexibility of siloxane chains is very important for the permeability and selectivity. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys, 35: 699–707, 1997     

Synthesis and characterization by MALDI-TOF MS of polycyclic siloxanes derived from p-substituted novolac resins by MALDI-TOF MS

Novel polycyclic siloxane resins were prepared from phenol-formaldehyde novolac type resins by reacting them with dialkyl or diaryl dichlorosilanes under anhydrous and high dilution conditions. The formation of polycyclic species was confirmed by the detection of absolute masses by MALDI-TOF mass spectrometry. ¹H- and ²⁹Si-NMR confirmed the substitutions of phenolic hydroxy groups by siloxane bonds. Curing studies were conducted on the polycyclic siloxane resins as well as on the polycyclic siloxane resins incorporated into two types of polysiloxane gums. A trace amount of potassium hydroxide was used as a catalyst for the crosslinking of these systems. The blend of polysiloxane with 30 wt % polycyclic siloxane was found to be stable at the curing temperature. Differential scanning calorimetry and thermogravimetric analysis techniques were used to study the thermal profiles of these systems. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2429–2437, 1998     

Synthesis of photocrosslinkable fluorinated polydimethylsiloxanes: Direct introduction of acrylic pendant groups via hydrosilylation

The synthesis of photocrosslinkable fluorinated polydimethylsiloxanes was achieved through direct hydrosilylation with copoly(dimethyl)(methyl‐hydrogen) siloxane. First, the hydrosilylation of a fluorinated olefin allowed the introduction of a fluorinated group onto the polysiloxane. Then, a second hydrosilylation of allyl methyl methacrylate led to the polysiloxane bearing both fluorinated and photocrosslinkable groups. This method, compared with a previous method of copolycondensation, is shown to be easier and more efficient. All the new products synthesized were characterized by IR, ¹H NMR, ¹⁹F NMR, and ²⁹Si NMR. A formulation containing the fluorosilicone was crosslinked after being coated on a mesoporous membrane and was evaluated as a vapor permeation membrane. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3722–3728, 2000     

Amphiphilic block and statistical siloxane copolymers with antimicrobial activity

Statistical and block all‐siloxane copolymers containing quaternary ammonium salt (QAS) groups with biocidal activity as lateral substituents were synthesized as models for the study of the effect of the arrangement of the QAS groups in the copolymer chain on their antimicrobial activity. The bioactive siloxane unit was [3‐n‐octyldimethylammoniopropyl]methylsiloxane, and the neutral unit was dimethylsiloxane. The copolymers also contained siloxane units with unreacted precursor 3‐chloropropyl or 3‐bromopropyl groups. A small number of units containing highly hydrophilic 3‐(3‐hydroxypropyl‐dimethylammonio)propyl groups were introduced to increase the solubility of the copolymers in water. The bioactive and bioneutral units were arranged in the polymer chain either in blocks or in statistical order. The block copolymers differed in the number and length of segments. The copolymers were obtained by the quaternization of tertiary amines by chloropropyl or bromopropyl groups attached to polysiloxane chains. The arrangement of the bioactive groups was controlled by the arrangement of the halogenopropyl groups in the bioactive copolymer precursor. All model siloxane copolymers showed high bactericidal activity in a water solution toward the gram‐negative bacteria Escherichia coli and the gram‐positive bacteria Staphylococcus aureus. However, no essential differences in the activities of the copolymers with block and statistical arrangements of units were detected. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2939–2948, 2003     

Ionic organic/inorganic materials. I. Novel cationic siloxane copolymers containing quaternary ammonium salt groups in the backbone

The synthesis and characterization of some novel cationic siloxanes copolymers containing quaternary ammonium salt (QAS) groups in the backbone is reported in this article. One cationic oligomer having QAS in the backbone and reactive groups like 2,3‐epoxypropyl and 2‐hydroxy‐3‐chloropropyl (RCO) as well as 1,3‐bis(3‐aminopropyl)tetramethyldisiloxane or α,ω‐bis(3‐aminopropyl)oligodimethylsiloxane (AP) were used as precursors for this goal. Elemental analysis, IR and ¹H NMR spectroscopy, thermogravimetric analysis, and X‐ray photoelectron spectroscopy were used to characterize the obtained copolymers. The thermal stability of the cationic siloxane copolymer increased when the siloxane oligomer having a high number of siloxane units in the chain (AP) was used as a precursor. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3570–3578, 2002     

Synthesis and characterization of polyimide containing PEG/PDMS amphiphilic conetworks by hydrosilylation: Correlation between structure and properties

Soluble poly(imide‐siloxane)s were obtained by carefully designing the synthesis and introducing poly(ethylene glycol) (PEG) units, thereby making the system amphiphilic in nature. The solubility of the synthesized PEG containing poly(mide‐siloxane)s (PPIS) in various solvents was tested and their thermal properties were investigated. Polymeric siloxane networks were prepared by combining imide groups and hydrophilic PEG components with sufficient variability in their composition to analyze their physicochemical details. The amine groups of the imides were varied in their rigidity and bulkiness, and their effect on the mechanical and thermal properties was studied. Here we have also examined the surface property of the networks through contact angle measurements, morphology through SEM, existence of amorphous nature by WAXD, and their structure–property relationships were correlated. The thermal analysis revealed the phase separation of the three components poly(dimethyl siloxane) (PDMS), PEG, and imide, showing a tricomponent amphiphilic conetworks. The mechanical properties were found to be improved by the phase separated PPIS containing more rigid imide groups. The overall properties of the amphiphilic conetwork has the features of differing hydrophilicity, mobility, and morphology distributed across a matrix, which has a microphase separated design suitable for gas separation and biomedical applications. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1707–1726, 2007     

Thermally and oxidatively stable thermosets derived from preceramic monomers

Monomers 1,3-bis(4-phenylethynylphenyl)tetramethyldisiloxane and 1,7-bis(4-phenylethynylphenyltetramethyldisiloxyl)-m-carborane were synthesized and compared with bis(4-phenylethynylphenyl)dimethylsilane as potential preceramic precursors. These monomers were heated to free flowing liquids above 100°C and thermally polymerized above 300°C to form heat-resistant thermosets or ceramic residues. The ceramic yields for the silane (13%) and siloxane (30%) were much lower than that for the carborane (64%) monomer. The thermoset and ceramic made from the carborane monomer were the best thermally and oxidatively stable materials. After curing, the thermoset had a weight loss of only 6% and after pyrolysis, the ceramic residue had no additional weight loss up to 1000°C in air. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1033–1038, 1997     

Coupling polymerization of monofunctional allene derivatives with malonates bearing aryl halides moieties via π-allylpalladium complex

A novel polymerization method of allene derivatives with nucleophiles bearing aryl halide moieties (A-B type) is described. By the polymerization of hexylallene with malonates bearing an aryl iodide part, polymers consisting both of internal and exomethylene (exo) double bonds were obtained by mean of the coupling reaction of three different components in high yields. On the other hand, a polymer obtained from phenylallene was selectively composed of internal double bonds (E and Z). By the reaction of hexylallene with a malonate bearing two aryl halide moieties (A-B₂ type), a multibranched polymer was also obtained. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 2097–2103, 1997     

Ionic organic/inorganic materials. II. New linear and crosslinked poly(ethylene oxide)‐based ionomers by quaternization with chloroalkyl‐functionalized siloxanes

Siloxane‐modified cationic polyelectrolytes were synthesized through the quaternization reaction of a poly(ethylene glycol)‐based polymer containing tertiary amine groups in the chain with chloroalkyl‐functionalized siloxanes. Linear or crosslinked structures were obtained, depending on the functionality of the siloxane: a chloroalkyl‐monofunctionalized or ‐polyfunctionalized siloxane was used. The reaction occurred in solution with n‐propanol as a solvent and NaI as a catalyst. All products were characterized with elemental analysis and IR and ¹H NMR spectrometry. Viscometric measurements of the linear polymer in dilute aqueous solutions revealed typical polyelectrolyte behavior. The swelling capacities in various solvents of the crosslinked structures were determined. The thermal stability of the crosslinked cationic structures obtained with a polyfunctional siloxane as a quaternization agent was much higher than that of the parent polymer. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3720–3728, 2004     

Three-component coupling polymerization of bisallene,aryl dihalides,and nucleophiles via π-allylpalladium complex. II. Effect of nucleophiles on polymerization

A novel palladium-catalyzed three-component polycondensation of 1,2,10,11-dodecatetraene, 4,4′-diiodobiphenyl, and nucleophiles was carried out using various carbanions and amines as a nucleophilic part. The polymerization with various sodium diethyl malonates produced polymers in high yields. Particularly, no exo-double bond was detected in the polymers prepared from sodium diethyl malonates bearing substituents directly on the carbanion center. The ratios of E- and Z- isomeric units in the polymers were dependent on the structure of the nucleophiles used. Other carbanions with appropriate electron-withdrawing groups such as sulphones and ketones can be also used as a nucleophile for the present polycondensation. Within heteronucleophiles examined, cyclic amines were suitable to produce polymers in high yields. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1211–1218, 1997     

Poly(siloxane‐urethane) crosslinked structures obtained by sol‐gel technique

Poly(siloxane‐urethane) crosslinked structures were prepared from isophorone diisocyanate, α,ω‐bis(hydroxybutyl)oligodimethylsiloxane and a new hybrid diol containing hydrolysable Si? OC₂H₅ groups besides OH groups. The latest was synthesized by the acid‐catalyzed reaction between 1,3‐bis(3‐glycidoxypropyl)tetramethyldisiloxane and 3‐aminopropyltriethoxysilane. The formations of the urethane groups along the polymer backbone as well as the formation of the silica domains were first confirmed by the presence of the specific bands in Fourier transform infrared spectra. The resulted materials were characterized using differential scanning calorimetry, thermogravimetric analysis and scanning electron microscopy. The results of the dynamic mechanical analysis (DMA) performed at various frequencies revealed shape memory capabilities for some of the obtained structures. The silica formed because of the hydrolysis‐condensation reactions proved to have reinforcing effect upon siloxane‐urethane structure also evidenced by DMA and increasing water vapor sorption capacity as was measured by dynamic vapor sorption. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Syntheses of poly(siloxane)-supported zirconocene catalysts and application to olefin polymerizations

Poly(siloxane)s with bisindenyl, bisfluorenyl, bis(1,2,3,4-tetramethylcyclopentadienyl), bis(2,4,7-trimethylindenyl) and monoindenylmethyl side groups were synthesized by condensation of the corresponding dichlorosilanes and water. For reference, diphenylsilanediol or hydroquinone was also employed in place of water. A series of poly(siloxane)-supported zirconocene catalysts were then prepared from these precursors and applied to ethene and propene polymerizations as well as to the copolymerization of ethene with 1-octene in the presence of methylalumoxane. The polymerization activity of the new supported metallocenes depends drastically upon the substituents in the siloxane backbone. The zirconocene catalysts supported on poly(bisindenylsiloxane) and poly(bisfluorenylsiloxane) give the highest activities for ethene and propene polymerizations, respectively. The weight-average molecular weights of the polymers are also markedly dependent upon the substituents. On the other hand, the molecular mass distributions (MMD) are generally not so sharp, suggesting that the active species formed in these supported catalysts are not uniform. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36 : 421–428, 1998     

Novel siloxane‐carrying dithiol derived from 5‐membered cyclic dithiocarbonate and its curing reactions for coating application

A new efficient and straightforward method to convert amines into siloxane‐thiol hybrid molecules was developed. The method relies on the nucleophilic addition of amines to a cyclic dithiocarbonate having siloxane moiety (DTC‐Si), and the successive ring‐opening reaction of the dithiocarbonate moiety to give the corresponding acyclic thiourethane having a thiol moiety. Based on this method, amine‐terminated poly(propylene glycol) was successfully transformed into the corresponding polyether having thiol‐terminals and siloxane groups. In the presence of moisture, the alkoxysilyl moiety underwent condensation reaction to make the polyether cured into a transparent resin having solvent‐resistance. Addition of bisphenol A diglycidyl ether (Bis A‐DGE) to the curing process resulted in two simultaneous reactions, i.e., (1) condensation of siloxane part and (2) addition reaction of the thiol terminal and the epoxide group. When this curing process was carried out on a glass surface, the siloxane part reacted with silanol group on the surface, forming a coating layer having excellent mechanical toughness graded as maximum 7H by pencil toughness test (JIS‐K5400). © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5119–5126, 2005     

Synthesis and characterization of phosphonate‐containing polysiloxanes

Phosphonate‐functionalized polysiloxanes have been prepared with a new siloxane/phosphonate monomer. The reaction of 3‐chloropropylmethyldimethoxysilane with trimethylphosphite or triethylphosphite produces several new monomers containing pendant phosphonate groups. Copolymerization with dimethyldimethoxysilane has produced polymers soluble in most organic solvents. The acid hydrolysis of the phosphoryl esters has produced hydrophilic siloxane polymers containing phosphonic acid groups. The thermal properties of the polymers and several related small molecules have been compared with thermogravimetric analysis. Both the monomers and the resulting polymers have been characterized with ¹H, ¹³C, ³¹P, and ²⁹Si NMR. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 48–59, 2003     

Noncovalent linkage of telechelic oligo(dimethylsiloxanes) via end group attachment of host‐cyclodextrins and guest‐adamantanes or guest‐ferrocenes

In this article, we report the noncovalent linkage of terminal substituted oligo(dimethylsiloxanes) bearing cyclodextrins (CD) as host endgroups and adamantan or ferrocene, respectively, as guest endgroups. Structural characterization was performed by ¹H NMR‐, IR‐, and mass spectroscopy. Electron microscopy studies show significant differences in the surface structure of the individual derivatives. In addition, the ferrocene‐terminated di‐and poly(dimethylsiloxanes) are distinguished by a red‐ox activity and reversibility, which also makes the complexes between the ferrocene‐ and CD functionalized siloxanes switchable via electrochemical stimuli. The evidence for a successful complexation of the end groups, and thus the successful supramolecular formation of the siloxane strands, was even performed by shift of the protons in the ¹H NMR spectra. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2472–2482     

Simplified synthesis of carbohydrate‐functional siloxanes via transacetalation. I. Glucose‐functional siloxanes

Carbohydrate‐functional siloxanes (CHFSs) that exhibit high intermolecular interactions and good environmental friendliness have successfully been synthesized by acid‐catalyzed transacetalation between an acetal‐functional siloxane and glucose in dimethylformamide/dioxane mixed solvents. Activated clay has proven to be a good catalyst because of its high activity and its easy removal from the product. Acetal‐functional siloxanes as starting materials can be easily synthesized in good yields by hydrosilylation between Si? H‐functional siloxanes and acrolein diethyl acetal. This method has the following advantages: (1) the inexpensive materials used, (2) the simplified process employed, and (3) the high yield achieved. Because the carbohydrate moieties in these materials have the nature of strong intermolecular interactions and are highly hydrophilic, CHFSs exhibit very high bulk viscosities in comparison with the corresponding acetal‐functional siloxanes and good solubilities in polar solvents such as dimethylformamide and dimethyl sulfoxide. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3336–3345, 2003     

Polycondensation of trialkoxysilane monomers accelerated by neighboring group participation of urea moiety

(Phenylaminomethyl)trimethoxysilane (= α‐amino‐siloxane) was treated with various isocyanates to obtain a series of siloxanes having urea moieties (= α‐urea‐siloxanes). Their hydrolysis‐condensation reactions were monitored with ²⁹Si NMR, to reveal that they exhibited much higher reactivity than a urea‐siloxane derived from [3‐(phenylamino)propyl]trimethoxysilane (= γ‐amino‐siloxane). When compared with the derivation of the γ‐amino‐siloxane into the corresponding γ‐urea‐siloxane, those of the α‐amino‐siloxane into the corresponding α‐urea‐siloxanes were accompanied by much larger shifts of the ²⁹Si NMR signal toward a higher magnetic field. These results suggested that the location of the urea moiety in the α‐urea‐siloxanes was favorable to its intramolecular coordination to the silicon atom to exhibit its “neighboring group participation” that promoted transformation of the tetravalent silicon center into the pentavalent one, which is more electrophilic to make the siloxanes more susceptive to undergo the hydrolysis and condensation reactions. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6654–6659, 2008     

Synthesis and crosslinking reaction of poly(thiourethane)s having a siloxane moiety in the side chain

Poly(thiourethane)s having a siloxane moiety in the side chain were synthesized with a 5‐membered cyclic dithiocarbonate (DTC) having a siloxane group as a building block. The synthetic pathway consisted of (1) an addition reaction of the DTC with diamines and (2) polyaddition reactions of the resulting dithiols with diisocyanates. The siloxane moiety in the polymer side chain underwent a self‐condensation reaction upon exposure to moisture, and this led to a successful crosslinking reaction of the poly(thiourethane). The crosslinking on a silicate surface was accompanied by condensation between the siloxane side chain of the polymer and the silanol group on the surface, giving the corresponding surface that was permanently coated with the crosslinked polymer. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6492–6502, 2005