PS-h-PDMS

Hu et al. [48] studied the addition of PS-h-PDMS diblock copolymer to the PS/PDMS blend. A maximum interfacial tension reduction of 82% was achieved at a critical concentration of 0.002% diblock added to the PDMS phase. At a fixed PS homopolymer molecular weight, the reduction in interfacial tension increases with increasing the molecular weight of PDMS homopolymer. Moreover, the degree of interfacial tension reduction was found to depend on the homopolymer the diblock is mixed with when the copolymer was mixed into the PS phase, the interfacial tension reduction was much less than that when the copolymer was blended into the PDMS phase. This behavior suggested that the polymer blend interface may act as a kinetic trap that limits the attainment of global equilibrium in these systems. 

Flocculation studies (6) indicated that the mechanism of steric stabilization operates for the PMMA dispersions. The stability of PMMA dispersions was examined further by redispersion of the particles in cyclohexane at 333 K. Above 307 K, cyclohexane is a good solvent for PS and PDMS, and if the PS-PDMS block copolymer was not firmly anchored, desorption of stabilizer by dissolution should occur at 333 K followed by flocculation of the PMMA dispersion. However, little change in dispersion stability was observed over a period of 60 h. Consequently, we may conclude that the PS blocks are firmly anchored within the hard PMMA matrix. However, the indication from neutron scattering of aggregates of PS(D) blocks in PMMA particles may be explained by the observation that two different polymers are often not very compatible on mixing (10) so that the PS(D) blocks are tending to... 

The amount of meso and racemic dyads in PS was 0.43 and 0.57, respectively. The conformational parameters for PDMS were taken from ref. 112.) The strong difference in the half-peak widths q /2 is a clear indication of a higher conformational rigidity for PS, which is also suggested by the characteristic ratios relative to the freely rotating chain = o/ [see Eqn. (3.3.4)], the value of which is 4.4 and 1.9 for PS and PDMS, respectively. 

Fig. 15 Top-. 3D view (measured by AFM) of a typical hole obtained by dewetting a PS film on a PDMS-coated substrate at temperatures close to the glass transition of PS. h x,f) is the profile of the film, ho is the initial height of the film, H t) Is the height of the front, L(t) is the dewetted distance, W(i) is the width of the rim, and v x,t) is the velocity of the film. Bottom typical 3D cross-sections showing the asymmetric shape of the rim at early stages and comparatively low temperatures (left) and the more symmetric shape at late stages or at high temperatures (right)...

L. H. Sperling and H. D. Sarge, III, Joined and Sequential Interpenetrating Polymer Networks Based on Poly(dimethylsiloxane), J. Appl. Polym. Sci. 16(11), 3041 (1972). PDMS/PS and PDMS/PMMA sequential IPNs and ABCPs. 

Samples were either run at atmospheric pressure in quartz cells as a function of temperature (e.g. PS-h in CH-d [4,5] or in AC-d [6]) or were loaded into the pressure cell with the appropriate isotopic ratio to eliminate (x - 0.512 for PDMS in CO2) or minimize (e.g. x = 0.2 for PS-h in CH-d) the contribution of the total scattering term [Eq.(l)]. The maximum area accessible to the neutron beam is 2 cm and the path lengths of the quartz or pressure cells may be adjusted over the range, 0.1 to 2.0 cm. to optimize the transmission. The temperature was controlled by circulating fluids ( 0.1 °K) and pressure was applied and measured using a screw-type pressure generator and a precision digital pressure indicator, respectively. 

There is no single criterion for the best material for soft lithographic stamps. Different applications require different combinations of properties. Table 1 fists the physical properties of six of the most common polymers used in soft lithography PDMS (h-PDMS and soft-PDMS (s-PDMS))," PMMA, PS, and PPPE."" ... 

Fig. 23. Variation of surface layer thickness with molecular weight of the stabilizing polydimethylsiloxane (PDMS) chain. Hydrodynamic thickness <5109) PMMA particles (O), PS particles ( ), micellar dispersions (A) from viscosity data x, thickness h from surface coverage data of PMMA particles assuming a prolate ellipsoid model for the...

PB PBI PBMA PBO PBT(H) PBTP PC PCHMA PCTFE PDAP PDMS PE PEHD PELD PEMD PEC PEEK PEG PEI PEK PEN PEO PES PET PF PI PIB PMA PMMA PMI PMP POB POM PP PPE PPP PPPE PPQ PPS PPSU PS PSU PTFE PTMT PU PUR Poly(n.butylene) Poly(benzimidazole) Poly(n.butyl methacrylate) Poly(benzoxazole) Poly(benzthiazole) Poly(butylene glycol terephthalate) Polycarbonate Poly(cyclohexyl methacrylate) Poly(chloro-trifluoro ethylene) Poly(diallyl phthalate) Poly(dimethyl siloxane) Polyethylene High density polyethylene Low density polyethylene Medium density polyethylene Chlorinated polyethylene Poly-ether-ether ketone poly(ethylene glycol) Poly-ether-imide Poly-ether ketone Poly(ethylene-2,6-naphthalene dicarboxylate) Poly(ethylene oxide) Poly-ether sulfone Poly(ethylene terephthalate) Phenol formaldehyde resin Polyimide Polyisobutylene Poly(methyl acrylate) Poly(methyl methacrylate) Poly(methacryl imide) Poly(methylpentene) Poly(hydroxy-benzoate) Polyoxymethylene = polyacetal = polyformaldehyde Polypropylene Poly (2,6-dimethyl-l,4-phenylene ether) = Poly(phenylene oxide) Polyp araphenylene Poly(2,6-diphenyl-l,4-phenylene ether) Poly(phenyl quinoxaline) Polyphenylene sulfide, polysulfide Polyphenylene sulfone Polystyrene Polysulfone Poly(tetrafluoroethylene) Poly(tetramethylene terephthalate) Polyurethane Polyurethane rubber... 

Figure 5.1. Molecular structures of the chemical repeat units for common polymers. Shown are (a) polyethylene (PE), (b) poly(vinyl chloride) (PVC), (c) polytetrafluoroethylene (PTFE), (d) polypropylene (PP), (e) polyisobutylene (PIB), (f) polybutadiene (PBD), (g) c/5-polyisoprene (natural rubber), (h) traw5-polychloroprene (Neoprene rubber), (i) polystyrene (PS), (j) poly(vinyl acetate) (PVAc), (k) poly(methyl methacrylate) (PMMA), ( ) polycaprolactam (polyamide - nylon 6), (m) nylon 6,6, (n) poly(ethylene teraphthalate), (o) poly(dimethyl siloxane) (PDMS).

Polymers and copolymers were laboratory-prepared samples. Samples W4 and W7 of the diblock copolymer AB poly(styrene-fo-tetramethylene oxide) (PS—PT) were synthesized by producing a polystyrene prepolymer whose terminal group was transformed to a macroinitiator for the polymerization of THF. Samples B13 and B16 of the diblock copolymer AB poly[styrene-h-(dimethyl siloxane)] (PS-PDMS) were prepared by sequential anionic polymerization. Samples of statistical copolymers of styrene and n-butyl methacrylate (PSBMA) were produced by radical copolymerization. Details of synthetic and characterization methods have been reported elsewhere (15, 17-19). 

A, air H, water W, waste Al, aliphatic amine AA, aromatic amine PAA, polyaromatic amine ABDAC, alkylbenzyldimethylammonium chloride AME, alkylamine ethoxylates T, tertiary amine PE, polyethylene PS/DVB, polystyrene/divinylbenzene PDMS, polydimethylsiloxane PA, polyacrylate PAB, polyacrilonitrilbutadiene. 

Living anionic ROP of strained silicon-bridged [l]ferrocenophanes (Section 3.3.3) provides an excellent route to PFS block copolymers with controlled block lengths and narrow polydispersities (PDI<1.1) [82-84]. Diblock, triblock, and more complex architectures are now known for a wide variety of organic, inorganic, or even other polyferrocene coblocks. The prototypical materials prepared in the mid-1990s were the diblock copolymers polyferrocenylsUane-h-polydimethylsiloxane (PFS-fo-PDMS) 3.52 and polystyrene-b-polyferrocenylsUane (PS-i -PFS) 3.54 83j. As shown in Scheme 3.4, initial anionic polymerization of monomer 3.21... 

Poly sty rene-polydimethylsiloxane block copolymer PS-PDMS (polysimethylsiloxane) blend Four 30 cm 10 pm packings (Polymer Laboratories 10, 105, 1Q4 103 C,H,C1, (tetrachloroethylene) quoted pore size concentration 5 x 10"3 g/cm 3 or less RI, FALLS (dual detector) Compositional heterogeneity correlation with MWD 54... 

The solution viscosity of cyclic polymers is lower than those of their linear analogues. The viscosity of cyclic and linear PS was preferentially studied and compared in cyclohexane, a theta solvent. Quite similar intrinsic viscosity ratios, [>/]c/[>/]i/ were determined by several research groups for this system for instance, values of 0.64-0.70 depending on the molar mass, of 0.67, and of 0.65 are reported. However, at high molar masses (>20 000gmor ), the ratio of intrinsic viscosities was found to approach unity.A similar tendency was reported also for cyclic and linear poly(2-vinylpyridine) and polybutadiene. For cyclic and linear PDMS, the ratio of intrinsic viscosities, [r ]cl[h] i under 0-conditions in bromohex-ane at 18 °C, was found to be equal to 0.66. ... 

Figure 34 (a) Schematic presentation of the model for the (PI)(PS) (PDMS) miktoarm starterpolymer, consisting of dark (PI), gray (PDMS), and white (PS) cylinders with specific shapes, (b) Presentation of the confinement to lines (filled circles). Reprinted from Yamauchi, K. Takahashi, K. Hasegawa, H. etal. Macromolecules 2003, 36,6962. ... 

---