Polydimethylsiloxane-b-polystyrene

Block polymers containing polydimethylsiloxane soft blocks have been the subject of considerable recent synthetic activity. In particular, polydimethylsiloxane-b-polystyrene polymers have received considerable attention as thermoplastic elastomers. For the most part, anionic polymerization methods have provided the most successful routes to the preparation of these block polymers. Among the most notable papers in this field are those of Dean, Saam et al, Juliano, and Bajaj and coworkers. Recently Chaumont and his coworkers have prepared polydimethylsiloxane-b-polystyrene polymers by the platinum catalyzed condensation polymerization of a,o)-vinyl terminated polystyrene oligomers with a,o)-hydrogen terminated polydimethyl-siloxanes. 

Polydimethylsiloxane-b-polystyrene polymers prepared by the new free radical synthesis display other characteristics typical of block polymers which distinguish them from physical blends of the two homopolymers. For example, solutions of the polymers show intense iridescence due to diffraction phenomena ascribed to the presence of two discrete uniformly dispersed microphases. These polymers are soluble in solvents such as nitropropane,... 

Table 2. Composition of Polydimethylsiloxane-b-Polystyrene Block Polymers... 

The most promising approach for preparing block copolymers of polystyrene (A) and polydimethylsiloxane (B) involves polymerization of cyclosiloxane monomers with living a,polystyrene anions (6). The original approach, however, gives materials contaminated with the... 

Malik, M. 1. Sinha, P. Bayley, G.M. Mallon, P. E. Pasch, H., Characterization of Polydimethylsiloxane-Block-Polystyrene (PDMS-B-Ps) Copolymers by Liquid Chromatography at Critical Conditions. Macromol. Chem. Phys. 2011, 212,1221-1228. 

Figure 15.2 Examples of 2D layers fabricated by convective assembly, [a] Examples of a crystal monolayer obtained from 1.1 jam PS latex particles. The crystalline order leadingto bright diffraction is revealed when illuminated with a white light from behind. [b) SEM images of a 100 nm gold nanoparticles monolayer assembled on a silicon surface (unpublished results], a monolayer (c], and a bilayer (d] obtained with 500 nm PS particles. The structures were first assembled on a flat PDMS substrate and then transferred onto a silicon wafer by printing. Abbreviations SEM, scanning electron microscopy PDMS, polydimethylsiloxane PS, polystyrene.

Figure 8.14 Ds of (a) polystyrenes in CCI4 and CeDe (measurements and symbols same as Figure 8.2), (b) polystyrene benzene and polystyrene cyclohexane (measurements and symbols same as Figure 8.3), (c) toluene solutions of (O) 15, ( ) 530, and ( ) 730 kDa polydimethylsiloxanes with single-Af (sohd line) and all-M (dashed line) fits, using PFGNMR measurements of Giebel, et al.(24) and Skirda, et al. 25), and (d) polyethylene oxide water (measurements and symbols same as Figure 8.1). Lines represent fits, one for each polymer solvent, to a joint stretched exponential in c and M.

In principle, A can be any polymer normally regarded as a hard thermoplastic, eg, polystyrene, poly(methyl methacrylate), or polypropylene, and B can be any polymer normally regarded as elastomeric, eg, polyisoprene, polybutadiene, polyisobutylene, or polydimethylsiloxane (Table 2). 

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... 

PCP = polychloroprene, PDMS = polydimethylsiloxane, PE = polyethylene, B-PE = branched polyethylene, L-PE = linear polyethylene, PEO = poly(ethylene oxide), PE VAc = poly(ethylene-co-vinyl acetate), PIB = polyisobutylene, PMMA = poly(methyl methacrylate), PnBMA = poly(n-butyl methacrylate), PiBMA = poly(isobutyl methacrylate), PtBMA = poly(t-butyl methacrylate), PP = polypropylene, PS = polystyrene, PTMO = poly(tetramethylene oxide) or polytetrahydrofuran, PVAc = poly(vinyl acetate). 

Ye, C.H., Singh, G., Wadley, M.L., Karim, A., Cavicchi, K.A., Vogt, B.D. Anisotropic mechanical properties of aligned polystyrene-block-polydimethylsiloxane thin films. Macromolecules 46, 21 (2013)... 

Note also work of Aven and Cohen [146] on Dp of polystyrenes in polydimethylsiloxane tetrahydrofuran. B. Chu, et al. [147,148] report on the diffusion of dilute polymethacrylate... 

Satti, A. J. Ciolino, A. E. Villar, M. A. Schmidt, V. Giacomelli, C., Micelles Formed by Highly Asymmetric Polystyrene-i-Polydimethylsiloxane and Poly-styrene-b-poly[5-(N,N-diethylamino)isoprene] Diblock Copolymers. Langmuir 2010, 26,14494-14501. 

Gall, B. T. Thomann, R. Mulhaupt, R., Synthesis and Characterization of Semicrystalline Triblockcopolymers of Isotactic Polystyrene and Polydimethylsiloxane. J. Polym. Sci., Part A Polym. Chem. 2011, 49, 2339-2345. 

Systematic smdies on the microdomain morphology of linear ABC Mblock terpolymers (hereafter called linear ABC) are limited to several systems. Linear ABC samples were predominantly synthesized by sequential living anionic polymerizations, which limit the kinds of monomers. Thus, polystyrene (PS) and polyisoprene (PI) or polybutadiene (PB) as well as their hydrogenated polymers such as poly(ethylene-a/t-propylene) (PEP) or poly(ethylene-aft-butylene) (PEB) were used as the A and B blocks, while poly(2-vinylpyridine) (P2VP), poly(4-vinylpyridine) (P4VP), poly(methyl methacrylate) (PMMA), poly(tert-buthyl methacrylate) (PtBMA), poly(ethylene oxide) (PEO) or polydimethylsiloxane (PDMS) was used as... 

Figure 5 (a) RBS spectrum at 2.4 MeV for a 10% blended film of polystyrene-block-polydimethylsiloxane (PS-b-PDMS) copolymer in polystyrene. Data for the annealed sample have been shifted for clarity. The Si atoms are the most massive in the copolymer, and PDMS has a lower surface energy than that of PS hence the high energy recoils are due to Si near the film surface. Annealing induces the formation of two distinct Si-rich layers, which are separated by an Si-sparse interstitial layer of about 20 nm. (b) Concentration profile corresponding to the fit to the data for annealed sample. 

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