PS-h-PAA

Block copolymer vesicles, or polymersomes, are of continued interest for their ability to encapsulate aqueous compartments within relatively robust polymer bilayer shells (Fig. 7) [66, 67]. Eisenberg and coworkers were the first to report the formation of block copolymer vesicles from the self-assembly of polystyrene-h-poly(acrylic acid) (PS-h-PAA) block copolymers. They also have described the formation of a wide range of vesicle architectures in solution from the self-assembly of five different block copolymers PS-h-PAA. PS-h-PMMA, PB-h-PAA, polystyrene-h-poly(4-vinyIpyridinium methyl iodide), and polystyrene-h-(4-vinylpyridinium decyl iodide) [68]. Small uniform vesicles, large polydisperse vesicles, entrapped vesicles, hollow concentric vesicles, onions, and vesicles with hollow tubes in the walls have been observed and the formation mechanism discussed. Since vesicles could be prepared with low glass transition polymers such as PB [69, 70] and PPO [71], it has been established than these structures are thermodynamically stable and not trapped by the glassy nature of the hydrophobic part. 

Block copolymers in solution can be self-assembled into a variety of architectures. Micelles are common self-assembled stmctures formed by block copolymers when dissolved in a selective solvent , which is a good solvent for one of the polymer blocks but a poor solvent for the blocks of the other polymer. Binding one of the copolymer blocks with inorganic moieties leads to the formation of nucelles. The inorganic moieties are localized within the core of the micelles and coated with a thin shell of the other copolymer blocks. For example, Taton s group prepared a unidirectional structure of hybrid nucelles based on amphiphilic polystyrene-Wock-poly(acrylic acid) (PS-h-PAA) and gold nanoparticles (AuNPs) (Fig. 1) [25]. 

A method for preparation of a composite based on the three-dimensional nanosized copolymer template has been discussed [118]. The IPEC of the metallo-containing PEI-Ag polycation with the ionic amphiphilic diblock copolymer PS-h-PAA was obtained for further synthesis of encapsulated metal NPs. The silver NPs with diameter 20-40 nm were successfully synthesized in coronas of micelles (Fig. 24). In this case, PEI was used as both reducing and stabdizing agent. The cryo-TEM images suggest that the Ag content determines the size and spatial distribution of silver NPs. 

Fig. 24 Synthesis of silver NPs in the triple metallo-containing macromolecular co-assembly PS-h-PAA-Ag -PEI. (a) Procedure for preparation of Ag/PS-h-PAA composite, (b, c) Typical TEM images of Ag/PS-b-PAA composites with different Ag content (b) 0.012% (wt) PS-b-PAA, 0.02 molA- AgNOs and (c) 0.012.% (wt) PS-b-PAA, 0.05 mol/L AgNOa. Reprinted from [118] Copyright 2008 with permission from Elsevier...

Figure 14.19 Schematic illustrations of morphology evolution in (a) PS-h-PAA/PS-fc-PEO/PANI and (b) PMMA- -PAA/PAN1 complex aggregates in aqueous solution, [(a) Reprinted with permission from Palanisamy, A. and Q. Guo, J Phys Chem B (2014), 118, 12796-12803. Copyright (2014) American Chemical Society.] Palanisamy and Guo [94]. Reproduced with permission of The Royal Society of Chemistry.

Fig. 18 H-NMR spectra of an amphiphilic core-shell polymer brush with PS-b-PAA side chains ([S23 - b- AAi86]310) in (a) CD30D, and (b) CD30D/CDC13 (v/v = 1/1) [30], Reprinted by permission of ACS...

Spherical micelles formed from complexation ofPS-h-PAA and PMMA-h-PEO showed time-dependant evolution into hyperbranched structures. The interplay between segregation in PMMA/PS corona and complexation of PEO/PAA core as a function of molar ratio of PEO to PAA determines the structural evolution [72]. Gao et al. [73] studied hydrogen-bonding... 

Figure 14.17 TEM images showing collapsed PS domains on the corona of PS-f>-P2VP-f>-PEO/P(PEO-MA)-h-PAA-h-P(PEO-MA) micelles. Gohy et al. [66]. Reproduced with permission of John Wiley and Sons.

Fig. 8 (a) SEC curves of the PS macromonomer (PS-MA curve 1), the crude (curve 2) and the purified (curve 3) poly( ter t-butyl acrylate-gra/f-styrene) (PTBA-g-PS), and the esterified polymethylacrylate (PMA curve 4) backbone, (b) H NMR spectra of the macromonomer PSMA, the graft copolymer PTBA-g-PS and the final purified reaction product poly(acrylic acid-gra/f-styrene) (PAA-g-PS)... 

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. 

The polymerization of vinyl monomers in liquid and supercritical CO2 has been studied extensively. Patents were issued in 1968 to the Sumitomo Chemical Company [81] and in 1970 to Fukui et al. [82] for the preparation of homopolymers of polystyrene, poly(vinyl chloride), poly(acrylonitrile) (PAN), poly-(acrylic acid) (PAA), and poly(vinyl acetate) (PVAc), as well as the random copolymers PS-co-PMMA and PVC-co-PVAc. Additionally, a patent was issued in 1995 to Bayer AG [83] for the preparation of styrene/acrylonitrile copolymers in SCCO2. In 1986, the BASF Corporation was issued a Canadian patent for the precipitation polymerization of 2-hydroxyethylacrylate and various N-vinylcarboxamides in compressed carbon dioxide [84]. In 1988, Terry et al. attempted to homopolymerize ethylene, 1-octene, and 1-decene in SCCO2 for the purpose of increasing the viscosity of CO2 for enhanced oil recovery [85]. These reactions utilized free-radical initiation with benzoyl peroxide and r-butylperoctoate at 71 °C and 100-130 bar for 24-48 h. Although the resulting polymers were not well characterized, they were found to be relatively... 

Field emission scanning electron microscopy (FESEM) images of directed assembly of polystyrene (PS)/polyacrylic acid (PAA) blends using alternative MUAM/octadecanethiol (ODT) patterns with various periodicities (a-d) 1333, (e-h) 1000, (i-1) 667, and (m-p) 333 nm. The spin speeds were changed (a,e,i,m) 3000, (b,f,j,n) 5000, (c,gJ<,o) 7000, and (d,h,l,p) 9000 rpm fflc stands for the critical spin speed for each pattern periodicity. (Reprinted with permission from ACS.)... 

Fig. 5.23 AFM height images of PAA-h-PS/PS blends upon annealing to water vapor (during 3 days at 95 °C) obtained in aqueous media at two different pH values (/) pH 3.0 and (ii) pH 7.0. Right images above are 1 x 1 pm below images are 0.35 x 0.35 pm, and the height scale is 0-10 nm. As depicted in the cartoons, depending on the environmental pH values, the PAA either protonated or dissociated collapse or stretch respectively resulting in the formation of nanometer sized holes or grains. Reproduced with permission from ref. [130]...

N-vinylpyrrolidone) (PNVP) and amphiphilic PVA-h-PAN [33, 48). Hydrolysis of both the esters and the nitrile groups of the PVAc-h-PAN copolymers paved the way to a well-defined, pH-sensitive PAA-h-PVA compound [48, 50). Despite the low polyolefin content of the final material, 1-octene was used successfully as the comonomers of VAc in the block, and statistical radical polymerization processes were carried out in the presence of cobalt complexes [51]. Moreover, the resumption of styrene polymerization from a PVAc-Co(acac)2 macroinitiator was also considered, which led to the expected PVAc-b-polystyrene (PS) copolymer unfortunately, however, a poor control of the styrene block was observed in this case [52]. 

Hales K, Chen Z, Wooley KI, Pochan D J (2008) Nanoparticles with tunable internal structure from triblock copolymers of PAA-h-PMA-h-PS. Nano Lett 8 2023-2026... 

To study the solution property of novel amphiphilic hyperbranched graft copolymer chains, we further prepared amphiphilic hyperbranched poly(acrylic acid) grafted with short polystyrene copolymer (HB-PAA- -PS) with a large hydro-phihc hyperbranched PAA core and short hydrophobic PS grafted chains. The copolymer chains with different branching degrees of PAA core were carefully prepared and well confirmed by SEC, H NMR, and FT-IR. As well, the... 

Figure 6.20 (a) Schematic of polymersome formation of poiy(styrene)-biock-poly(acrylic acid) and intermittent contact mode AFM height imageof (b) PS,5-f>-PAA,5 vesicles and (c) PEG,4-fr-PLA, vesicles deposited on glass snbsirate. Conrtesy D. Wesner, S. Handschuh-Wang, H. Schonherr, unpublished data. 

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