Polystyrene-block-poly

Figure 9.17 Plot of log [i ]M versus retention volume for various polymers, showing how different systems are represented by a single calibration curve when data are represented in this manner. The polymers used include linear and branched polystyrene, poly(methyl methacrylate), poly(vinyl chloride), poly(phenyl siloxane), polybutadiene, and branched, block, and graft copolymers of styrene and methyl methacrylate. [From Z. Grubisec, P. Rempp, and H. Benoit, Polym. Lett. 5 753 (1967), used with permission of Wiley.]...

Fig. 7. Data of Parsonage et al. [77] on the adsorption of a series of block copolymers of polystyrene-poly-2-vinylpyridine. The ordinate is the measured surface density ( d 2) reduced by the density required for the nonadsorbing chains to overlap the abscissa is the solvent-enhanced size asymmetry of the block copolymer defined under Eq. 26. The form of this plot is that suggested by Eq. 28...

Polystyrene-PDMS block copolymers4l2), and poly(n-butyl methacrylate-acrylic acid)-PDMS graft copolymers 308) have been used as pressure sensitive adhesives. Hot melt adhesives based on polycarbonate-PDMS segmented copolymers 413) showed very good adhesion to substrates with low surface energies without the need for surface preparation, such as etching. 

Gong, Y., Huang, H., Hu, Z., Chen, Y, Chen, D Wang, Z. and He, X. (2006) Inverted to normal phase transition in solution-cast polystyrene-poly(methyl methacrylate) block copolymer thin films. Macromolecules, 39, 3369-3376. 

A polystyrene-poly(ethylene,l-butene)-polystyrene triblock copolymer is produced by the selective hydrogenation of the corresponding triblock copolymer in which the center block consists of random placements of 1,2-poly(1,3-butadiene) and 1,4-poly (1,3-butadiene) units. 

Much work on the preparation of nonaqueous polymer dispersions has involved the radical polymerization of acrylic monomers in the presence of copolymers having the A block the same as the acrylic polymer in the particle core 2). The preparation of polymer dispersions other than polystyrene in the presence of a PS-PDMS diblock copolymer is of interest because effective anchoring of the copolymer may be influenced by the degree of compatibility between the PS anchor block and the polymer molecules in the particle core. The present paper describes the interpretation of experimental studies performed with the aim of determining the mode of anchoring of PS blocks to polystyrene, poly(methyl methacrylate), and poly(vinyl acetate) (PVA) particles. 

Partial hydrogenation of acetylenic compounds bearing a functional group such as a double bond has also been studied in relation to the preparation of important vitamins and fragrances. For example, selective hydrogenation of the triple bond of acetylenic alcohols and the double bond of olefin alcohols (linalol, isophytol) was performed with Pd colloids, as well as with bimetallic nanoparticles Pd/Au, Pd/Pt or Pd/Zn stabilized by a block copolymer (polystyrene-poly-4-vinylpyridine) (Scheme 9.8). The best activity (TOF 49.2 s 1) and selectivity (>99.5%) were obtained in toluene with Pd/Pt bimetallic catalyst due to the influence of the modifying metal [87, 88]. 

Scheme 9.8 Semihydrogenation of olefin alcohols with Pd colloids stabilized by a block copolymer polystyrene-poly-4-vinyl pyridine.

For the hydrogenation ofpolystyrene-fo-polybutadiene-fo-polystyrene (SBS) block co-polymer with Ru-TPPTS complex as catalyst, Jang et al. [92] applied a poly-ether-modified ammonium salt ionic liquid/organic biphasic system (Fig. 41.3). 

A six-armed star polymer consisting of ethane substituted with polystyrene [poly(l-phenyl-ethane-1,2-diyl)] blocks ... 

E4 polystyrene-Z)/ocA -[l,4-polybutadiene-grq/Z -poly(styrene-co-acrylonitrile)] (copolymer from styrene and acrylonitrile grafted to a 1,4-polybutadiene-polystyrene two-block copolymer at unspecified sites of some of the but-2-ene-... 

Marie P, Herrenschmidt YL, Gallot Y. Study of the emulsifying power of the block copolymers polystyrene/poly(2-vinylpyridinium chloride) and polyisoprene/poly(2-vinylpyridinium chloride). Makromol Chem 1976 77 2773-2780. 

Platonova et al. reported a preparation method of Co nanoparticles having good dispersibility using block copolymer (polystyrene poly-4-vinyl piridine) mi-cells where Co was generated by the reduction of micells loaded with CoCl2 and by thermal decomposition of Co2(CO)s in micellar solutions of the block copolymers... 

Deters (14) vibromilled a blend of cellulose and cellulose triacetate. The acetic acid content of cellulose acetate decreased with grinding time (40 h) while that of the cellulose increased, suggesting the formation of a block or graft copolymer or of an esterification reaction by acetic acid developed by mechanical reaction. Baramboim (/5) dissolved separately in CO polystyrene, poly(methyl methacrylate), and poly(vinyl acetate). After mixing equal volumes of solutions of equivalent polymer concentration, the solvent was evaporated at 50° C under vacuum and the resultant product ball-milled. The examination of the ball-milled products showed the formation of free radicals which copolymerized. 

Poly(styrene)-poly(lsoprene) and polystyrene-poly(butadiene) block copolymers... 

Antonietti, M., S. Heinz, M. Schmidt, and C. Rosenauer. 1994. Determination of the micelle architecture of polystyrene/poly(4-vinylpyridine) block copolymers in dilute solutiMHcromolecule 7 3276-3281. 

The carbanion pump method has been successfully applied for the preparation of different block copolymers including poly(ethylene oxide)-block-polystyrene, poly(ethylene oxide)-block-polystyrene-block-poly(ethylene oxide), poly(ethylene oxide)-block-poly(methyl methacrylate), poly(ethylene oxide)-block-poly(methylmethacry-late)-block-poly(ethylene oxide) (shown in Scheme 14), and poly(ferrocenyldimethylsilane)-block-(methyl methacrylate) <2004MI856, 2004MM1720, 2006MI(928)292>. 

The structures formed by polystyrene-poly(propylene imine) dendrimers have also been analyzed. Block copolymers with 8, 16, and 32 end-standing amines are soluble in water. They have a critical micelle concentration of the order of 10"7 mol/1. At 3x10 4 mol/l they form different types of micelles. The den-drimer with eight amine groups (80% PS) form bilayers. The dendrimer with 16 amine groups (65% PS) forms cylinders and the dendrimer with 32 amine groups (50% PS) forms spherical micelles [38,130,131]. These are the classical lamellar, cylindrical, and spherical phases of block copolymers. However, the boundary between the phases occurs at very different volume fractions, due to the very different packing requirements of the linear polymer and spherical dendrimer at the interphase. 

Block copolymers of butadiene and vinyl-2-naphtalene (BVN) have been synthetized and studied by the same techniques as polybutadiene-poly(a-methyl styrene) and polystyrene-polybutadiene block copolymers86,87. They exhibit the same structures, namely lamellar and cylindrical as SB and BMS block copolymers86,87. ... 

On the contrary, copolymers polystyrene-poly(ethylene oxide) (SEO), poly-butadiene-poly(ethylene oxide) (BEO), poly(ethyl methacrylate)-poly(ethylene oxide) (EMAEO) and polystyrene-poly(e-coprolactone)(SCL) exhibit well organized periodic structures. Copolymers SEO261-266), BEO267-270) and SCL27 ) have been studied in the dry state and in a preferential solvent for each type of block, while copolymers EMAEO have only been studied in the dry state272-274). 

Copolymers with a hydrophobic polyvinyl block and a hydrophilic polypeptide block like polybutadiene-poly(L-lysine) (BK), polystyrene-poly(L-lysine) (SK),poly-butadiene-poly(L-glutamic acid) (BE), and polystyrene-poly(L-glutamic acid) (SE) are obtained by action of HC1 and HBr on copolymers BCK, SCK, BG, and SG, respectively23. ... 

So far we have discovered very few polymerization techniques for making macromolecules with narrow molar mass distributions and for preparing di-and triblock copolymers. These types of polymers are usually made by anionic or cationic techniques, which require special equipment, ultrapure reagents, and low temperatures. In contrast, most of the commodity polymers in the world such as LDPE, poly(methyl methacrylate), polystyrene, poly(vinyl chloride), vinyl latexes, and so on are prepared by free radical chain polymerization. Free radical polymerizations are relatively safe and easy to perform, even on very large scales, tolerate a wide variety of solvents, including water, and are suitable for a large number of monomers. However, most free radical polymerizations are unsuitable for preparing block copolymers or polymers with narrow molar mass distributions. 

Few examples of the homogeneous diblock-incompatible homo-polymer behavior have been reported. One that has received considerable attention is the system polystyrene-poly-a-methylstyrene (2). Block copolymers of styrene and a-methylstyrene exhibit a single loss peak in dynamic experiments (2,3) and have been shown to be thermorheologi-cally simple (4) hence they are considered to be homogeneous. Mechanical properties data on these copolymers also has been used to validate interesting extensions of the molecular theories of polymer viscoelasticity (2,3,4). 

In this system using a polystyrene containing block copolymer, the polystyrene segment should readily partition into the lipophilic polystyrene particle core while the poly(FOA) or PDMS block is solubilized in the CO2 continuous phase to provide steric stabilization and prevent coagulation. In comparison of the polystyrene-b-poly(FOA) diblock copolymers to the polystyrene-b-PDMS diblock copolymers, it was found that the use of a polystyrene-b-PDMS stabilizer gives much more monodisperse particles. This most likely arises from the synthetic technique employed in the surfactant synthesis. The blocks in the polystyrene-b-PDMS block copolymers have a much narrower polydispersity than the blocks in the polystyrene-b-poly(FOA) block copolymers. It was noted that the particles obtained in... 

Gervais M, Gallot B (1973) Phase diagram and structural study of polystyrene - poly(ethylene oxide) block copolymers. 1. Systems polystyrene/poly(ethylene oxide)/diethyl phthalate. Makromol Chem 171 157-178... 

Chen and Gardella used this surface engineering strategy to create siloxane-rich surfaces [40]. Their approach involved the blending of a homopolymer (A) with a block copolymer composed of a block with the same chemical identity as the homopolymer (A) and a block of PDMS. For all homopolymer types studied (polystyrene, poly(cc methyl.styrene) and Bisphenol A polycarbonate), XPS analysis of Si C ratios revealed a significant enrichment of the PDMS... 

For a general review on supramolecular chemistry with dendrimers, the reader is referred to an excellent paper of Zimmerman et al. [18]. Because of our acquaintance with the polylpropylene imine) dendrimers, we will restrict ourselves in this Chapter to some examples of supramolecular behaviour of these systems as investigated in our laboratory. Three systems will be discussed (Figure 1) the dendritic box, which can encapsulate guest molecules, the polystyrene-poly(propy-lene imine) block copolymer superamphiphiles, and alkyl-decorated dendrimers, which function as unimolecular micelles, and show surprising aggregation behaviour. However, first the synthesis and properties of the poly(propylene imine) dendrimers will be discussed to demonstrate some typical dendrimer features. 

To obtain polystyrene-poly(propylene imine) block copolymers, the divergent dendrimer synthesis as described in 2.1 was performed onto the PS-CH2-O-CH2-CH2-CH2-NH2 core molecule, with M = 3.2kgmor (based on GPC of PS-CH2-OH). 

Figure 13 The polystyrene-poly(propylene imine) block copolymer...

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