Characterization of Polydimethylsiloxane-block-polystyrene (PDMS-b-PS) Copolymers by Liquid Chromatography at Critical Conditions (original) (raw)
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Polymer International, 2010
and poly(DMS-block-TMSHEMA) copolymers thus obtained were characterized using Fourier transform infrared and 1 H NMR spectroscopy and differential scanning calorimetry. After the deprotection of trimethylsilyl groups, poly(DMS-block-HEMA) and poly(DMS-block-EMA) copolymer film surfaces were analysed using scanning electron microscopy and X-ray photoelectron spectroscopy. The effects of the PDMS concentration in the copolymers on both air and glass sides of films were examined. The PDMS segments oriented and moved to the glass side in poly(DMS-block-EMA) copolymer film while orientation to the air side became evident with increasing DMS content in poly(DMS-block-HEMA) copolymer film. The block copolymerization technique described here is a versatile and economic method and is also applicable to a wide range of monomers. The copolymers obtained have phase-separated morphologies and the effects of DMS segments on copolymer film surfaces are different at the glass and air sides. Figure 4. 1 H NMR spectra of (a) PDMS, (b) PDMS-MAI, (c) poly(DMS-b-TMSHEMA) and (d) poly(DMS-b-HEMA).
European Polymer Journal, 2013
The structure of thin microphase-separated polystyrene-block-polydimethylsiloxane (PS-PDMS) films has been studied using state-of-the-art top-down and cross-sectional electron microscopy. This is the first time that the profile of PS-PDMS films has been measured in situ and these measurements allowed us to image the shape of the PDMS domains within the film as well as examine the wetting behavior of the block copolymer film on a variety of substrates. It was found that for each polymer, substrate chemistry and annealing method combination examined, there was a small range of film thicknesses whereby the films exhibited the optimal characteristics of high levels of ordering without dewetting or multilayering. Specifically, the optimum thickness for films treated by thermal annealing was greater than that for the equivalent solvent annealed film; a change that was correlated with morphology variations related to solvent swelling of the solvent annealed films. The surface chemistry also induced changes in the optimum film thickness. Selective surfaces were shown to control whether a PDMS wetting layer was formed or not, leading to either thicker or thinner wetting optimum film thicknesses; while undulating morphologies were observed for less selective surfaces. Concomitant changes in the periodicity were then hypothesized to occur as a result of confinement effects and the selectivity of the surface.
Journal of Polymer Science Part A: Polymer Chemistry, 2011
High molecular weight poly(dimethylsiloxane)/semicrystalline cycloaliphatic polyester segmented copolymers based on dimethyl-1,4-cyclohexane dicarboxylate were prepared and characterized. The copolymers were synthesized using a high trans content isomer that afforded semicrystalline morphologies. Aminopropyl-terminated poly(dimethylsiloxane) (PDMS) oligomers of controlled molecular weight were synthesized, end capped with excess diester to form a diester-terminated oligomer, and incorporated via melt transesterification step reaction copolymerization. The molecular weight of the polysiloxane and chemical composition of the copolymer were systematically varied. The polysiloxane segment was efficiently incorporated into the copolymers via an amide link and its structure was unaffected by low concentrations of titanate transesterification catalyst, as shown by control melt experiments. The homopolymer and copolymers were characterized by solution, thermal, mechanical, and surface techniques. The segmented copolymers were microphase separated as determined by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and by transmission electron microscopy (TEM). It was demonstrated that relatively short poly(dimethylsiloxane) segment lengths and compositions were required to maintain single phase melt polymerization conditions. This was, in fact, the key to the successful preparation of these materials. The copolymers derived from short poly(dimethylsiloxane) segments demonstrated good mechanical properties, melt viscosities representative of single phase polymer melts, and were easily compression molded into films. ᭧ 1997
Synthesis and thermal properties of diphenylsiloxane block copolymers
Polymer, 2001
Three series of polydiphenylsiloxane (PDPS)-containing diblock copolymers were synthesized with controlled molecular weight and composition by sequential addition of the corresponding comonomers through a living anionic polymerization. These copolymers included poly(diphenylsiloxane-b-dimethylsiloxane) (PDPS/PDMS), poly(diphenylsiloxane-b-methylphenylsiloxane) (PDPS/PMPS), and poly(diphenylsiloxane-b-methyltri¯uoropropylsiloxane) (PDPS/PMFPS). The structural effect of the soft segment of these PDPS-containing diblock coploymers on the mesophase transition behaviors was examined. The observations with differential scanning calorimetry (DSC) and polarized optical microscopy (POM) were combined to determine the actual thermal transition behaviors. Critical compositions for the appearance of these thermal transitions were determined for each series of the diblock copolymers. The thermal transition properties, such as temperature and peak shape were also correlated to the structures of the copolymers.
Morphologies of strongly segregated polystyrene-poly(dimethylsiloxane) diblock copolymers
Polymer, 1995
Five polystyrene-poly(dimethylsiloxane) (PS/PDMS) diblocks were synthesized by sequential anionic polymerization, and their morphologies characterized by small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). All materials are microphase-separated in toluene-cast films, and estimates of the interaction parameter x indicate that these materials are all strongly segregated. The experimentally determined phase diagram is strongly skewed towards low styrene volume fractions, even more than the styrene-isoprene (SI) diblock phase diagram, even though little conformational asymmetry should exist in the PS/PDMS system. The PS/PDMS diblocks form substantially larger microdomain structures than the analogous SI diblocks, reflecting the stronger segregation strength.
Synthesis and Characterization of Block Copolymers Using Polysiloxane Based Macroazoinitiator
Turkish Journal of Chemistry, 2004
Poly(dimethylsiloxane-b-styrene) (PDMS-b-PSt) and poly(dimethylsiloxane-b-methyl methacrylate) (PDMS-b-PMMA) block copolymers containing siloxane segments were studied by the radical polymerizations of vinyl monomers such as styrene (St) and methyl methacrylate (MMA) using polydimethylsiloxane based macroazoinitiator (PDM-MAI) in solution. PDM-MAI was synthesized by reacting hydroxyterminated polydimethylsiloxane (PDMS) and 4,4′-azobis(4-cyanopentanoyl chloride) (ACPC) having a thermodegradable azo-linkage. The polycondensation reaction between PDMS and ACPC (2:1, molar ratio) was carried out at room temperature. The polymerizations of St and MMA initiated by PDM-MAI were investigated using different PDM-MAI concentrations (1, 5, 10, and 15 wt.%) for various reaction times with a methyl ethyl ketone (MEK) / dichloromethane (DCM) solvent mixture (3:1, molar ratio) as the reaction medium at 65 ◦C. The decomposition temperature of MAI azo groups was determined to be 125 ◦C by thermogra...
Journal of Polymer Science Part A: Polymer Chemistry, 2008
The synthesis and spectroscopic characterization of a new family of amphiphilic multiblock and triblock copolymers is described. The synthetic methodology rests on the preparation of telechelic multifunctional and difunctional chain transfer agents easily available in two synthetic steps from commercially available polydimethylsiloxane-containing starting materials. Telechelic polymers thus synthesized are used as macromolecular chain transfer agents in the reversible addition fragmentation chain transfer (RAFT) polymerization of N,N-dimethylacrylamide (DMA) enabling the synthesis of (AB) n-type multiblock and ABA-type triblock copolymers of varying compositions possessing monomodal molecular weight distribution. (AB) n multiblock copolymers [(PDMA-b-PDMS) n ] were prepared with between 52 and 95 wt % poly(dimethylacrylamide) with number average molecular weights (M n) between 14,000 and 86,000 (polydispersities of 1.20-2.30). On the other hand, ABA block copolymers with DMA led to amphiphilic block copolymers (PDMA-b-PDMS-b-PDMA) with M n values between 9000 and 44,000 (polydispersities of 1.24-1.62).
Journal of Polymer Science Part A-polymer Chemistry, 1993
New polydimethylsiloxane (PDMS)-polyimide block copolymers were synthesized by the solution polycondensation of aminopropyl-terminated polydimethylsiloxane, 1,1-bis(4-aminophenyl)-2,2-diphenylethylene, and 3,3′,4,4′-benzophenonetetracarboxylic dithioanhydride in pyridine. New 1,3-bis(3-aminopropyl)tetramethyldisiloxane (BADS)-based random copolyimides were also prepared. The inherent viscosities of all the random and block copolyimides were in the range of 0.13–0.90 dL/g in N-methyl-2-pyrrolidone. These copolymers were soluble in N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and m-cresol. All the BADS-based random copolymers and PDMS-containing copolymers with PDMS content above 42 wt % were soluble in tetrahydrofuran and chloroform. Transparent or somewhat cpaque films were prepared by casting from the reaction solutions. The BADS-based random copolyimides had one glass transition temperature (Tg) in the whole composition ranges, which showed single phase nature of the copolymers. On the other hand, the PDMS-polyimide block copolymers had double TgS, indicating phase-separated morphology. The block copolymers containing PDMS content above 73 wt % behaved like a high temperature elastomer. © 1993 John Wiley & Sons, Inc.