Macromonomers, polystyrene synthesis

The second reported synthesis and application of 1,1-diphenylethylene macromonomers provided less ambiguous results and illustrated the potential of these macromonomers in synthesis of well-defined, hetero, three-armed, star-branched polymers [197, 198]. 1,1-Diphenylethylene-functionalized polystyrene macromonomers (74, 76) were prepared by the addition of poly(styr-yl)lithium with either l,3-bis(l-phenylethenyl)benzene (73, MDDPE) [198] or l,4-bis(l-phenylethenyl)benzene (75, PDDPE) [197] as shown in Eqs. (43) and (44) ... 

Fig.3.5 Schematic synthesis of Seesaw-type macromonomer polystyrene homopolymer...

The preparation procedure of narrowly distributed Seesaw-type macromonomer triblock copolymers, poly(tert-butyl acrylate)-polystyrene-poly(terr-butyl acrylate) (PtBA-PS-PtBA), with one alkyne group in the center of the PS block and one azide group at the end of each PtBA block is similar to that of macromonomer polystyrene homopolymers. The schematic synthesis of PtBA-PS-PtBA triblock copolymer is shown in Fig. 3.8. The corresponding DP values were calculated from area ratio of corresponding peaks in NMR spectrum, as shown in Fig. 3.9, and the molecular parameters of our obtained triblock copolymers macromonomer PiBA-PS-PtBA with different St and tBA molar contents and molar masses are summarized in Table 3.2. 

So far, there have been only few reports about the synthesis of amphipolar polymer brushes, i.e. with amphiphilic block copolymer side chains. Gna-nou et al. [115] first reported the ROMP of norbornenoyl-endfunctionalized polystyrene-f -poly(ethylene oxide) macromonomers. Due to the low degree of polymerization, the polymacromonomer adopted a star-like rather than a cylindrical shape. Schmidt et al. [123] synthesized amphipolar cylindrical brushes with poly(2-vinylpyridine)-block-polystyrene side chains via radical polymerization of the corresponding block macromonomer. A similar polymer brush with poly(a-methylstyrene)-Wocfc-poly(2-vinylpyridine) side chains was also synthesized by Ishizu et al. via radical polymerization [124]. Using the grafting from approach, Muller et al. [121, 125] synthesized... 

The reaction scheme for graft copolyelectrolyte synthesis by free radical copolymerization according to the macromonomer technique is shown in Scheme 15. Besides the aspect of how to control the constitution of the graft copolyelectrolyte, suitable characterization techniques for unequivocal proof of the attained copolymer structure will also be elucidated. The synthesis, characterization and properties of the inversely structured poly(acrylic acid)-g-polystyrene graft copolymers it are covered in another article in this volume [178]. 

The synthesis and purification of polystyrene methacryloyl macromonomers (PS-MA) in the molecular weight range Mn= 1000-2000 g mol 1 by living anionic polymerization of styrene (S), termination with ethylene oxide (EO), and subsequent reaction with methacrylic chloride has already been described in detail elsewhere [180] (see also Scheme 16). In this context it has to be emphasized that the hydroxyethyl-terminated PS-MA macromonomer precursor (PS-OH) as obtained after purification of the crude PS-OH by silica column chromatography (cyclohexane/dichloromethane 1/1 v/v) and as charged in the PS-MA synthesis still contains up to about 15 wt-% of non-functionalized polystyrene (PS-H). This PS-H impurity of the PS-MA macromonomer does not interfere with the PS-MA synthesis and the subsequent TBA/PS-MA copolymerization and is easily and conveniently removed from the resulting PTBA-g-PS graft copolymer (see below). 

Scheme 16 Reaction scheme for polystyrene (PS) macromonomer synthesis...

The synthesis of polystyrene-g-polytetrahydrofurane [188] was achieved by ATR copolymerization of methacrylic PTHF macromonomer, MA-PTHF, with styrene (Scheme 105). The PTHF macromonomer was synthesized by cationic ring opening polymerization of THF with acrylate ions, formed by the reaction of methacryloyl chloride and AgC104. The polydispersity indices of the graft copolymers determined by SEC ranged between 1.3-1.4. Kinetic studies revealed that the relative reactivity ratio of the macromonomer to St was independent of the molecular weight of PTHF. 

Scheme 72 Synthesis of alternating branched polystyrene/poly(ethylene oxide) poly-(macromonomers)...

Scheme 76 Synthesis of polystyrene macromonomer with two condensable amine groups...

The efficient synthesis of co-epoxide-ftmctionalized macromonomers in hydrocarbon solution at room temperature was achieved by optimizing the reaction of polymeric organolithium compounds with epichlorohydrin (eqn [28]). The direct addition of epichlorohydrin to a benzene solution of PSLi (Mn = 2000 g mol" ) formed the co-epoxide-frmctionalized polystyrene in only 9% yield the major products correspond to dimeric species (70%). Addition of THF to the solutions of PSLi and epichlorohydrin decreased the dimer yield to 10%... 

Problem 12,1 Suggest an ef cient route, via ATRP and CuAAC reaction, for the synthesis of a (meth)acry-late terminated polystyrene macromonomer, such as tu-acryloyloxy-polystyrene (DP - 50). 

The combination of ATRP and postpolymerization modi cation by CuAAC click chemistry can be employed to prepare well-de ned tu-(meth)acryloyl macromonomers in an ef cient manner. Thus, polystyrene (PSt) can be prepared by ATRP and subsequently derivatized to contain azide end groups. The azide-terminated polymers can then be reacted with alkyne-containing (meth)acrylate monomers to achieve near-quantitative chain-end functionalization by CuAAC reaction. An ef cient synthesis route is shown in Scheme P12.1.1. 

Suggest a route, via combination of ATRPand CuAAC reaction, foref cient synthesis of polystyrene-fc-poly(w-butyl acrylate)-methacrylate macromonomer, where each block in the copolymer chain has... 

Similar functionalization was described in the synthesis of poly(bisphenol-A carbonate)-gro/i-polystyrene 115 by a macromonomer technique. Pyridine rather than triethylamine was the proton acceptor of choice in the synthesis of the graft copolycarbonate by solution polycondensation [63]. 

NMR spectra were recorded on a Bruker WP-250 spectrometer in CDCI3. IR spectra were recorded on a Bruker IFS-110 spectrophotometer. SEC analyses were carried out using Waters m-Styragel columns with a porosity of 10, lO", 10 and 10 A and Lichrosphere Si 100 (7.5-pm particles) columns. Toluene was used as the eluent. A Waters 410 or RIDK 102 differential refractometer was used as the detector. Molecular masses were determined using polystyrene calibration. Synthesis of initial bs-macromonomer - 1,4-divinylhexamethyloctasilsesquioxane (3) and its non-functional derivative - l,4-bis(2-... 

Stadler and coworkers [213] have described another method for synthesis of 1,1-diphenylethylene-functionalized polystyrene macromonomers (84) as... 

As polymers that contain both hydrophilic and hydrophobic components aroused keen interest from theoretical and practical points of view over the past years, synthesis of amphiphilic branched copolymers by ring-opening metathesis polymerization of miscellaneous macromonomers is an important goal of the actual research. Thus, in order to obtain globular shape macromolecules that would present the same features as those exhibited by certain assemblies of molecules such as the micelles or the latices, with a bulk part different from the external surface, polymerization of norbornyl polystyrene-poly(ethylene oxide) macromonomer has been conducted in the presence of Schrock-type catalyst Mo(NAr)(CH/Bu)(OC(CH3)(CF3)2)2 in toluene at room temperature to produce poly-norbornene-polystyrene-poly(ethylene oxide) block copolymers (120) [88] [Eq. (52)]. 

First, Seesaw-type macromonomer =-S-S-(PS-N3)2 with one disulfide linkage at the chain center was firstly prepared by ATRP and azidation substitution reaction [2]. The Schematic illustration of synthesis of disulfide-functionalized Seesaw-type initiator and linear polystyrene macromonomer =-S-S-(PS-N3)2 is shown in Fig. 3.16. Further interchain clicking coupling... 

Fig. 3.16 Schematic illustration of the synthesis of disulfide-functioneilized seesaw-type initiator and linear polystyrene macromonomer =-S-S-(PS-N3)2...

As shown in Fig. 3.16, disulfide-functional initiator was prepared through a five-step synthesis. Figures 3.17 and 3.18 confirm the high purity of the initiator and the intermediate compounds. As calculated in Fig. 3.17, the integral area ratio of peak (a), peak (i) and peak (d+e) is 1.00/3.10/4.09, in consistency with its theoretical ratio of 1.00/3.00/4.00. Using this functional initiator. Seesaw-type polystyrene macromonomer =-S-S-(PS-Br)2 was successfully prepared by ATRP, and its typical NMR spectrum is shown in Fig. 3.19. 

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