Styrene-isobutyl methacrylate block

Novel sulfonated and carboxylated ionomers having "blocky" structures were synthesized via two completely different methods. Sulfonated ionomers were prepared by a fairly complex emulsion copolymerization of n-butyl acrylate and sulfonated styrene (Na or K salt) using a water soluble initiator system. Carboxylated ionomers were obtained by the hydrolysis of styrene-isobutyl-methacrylate block copolymers which have been produced by carefully controlled living anionic polymerization. Characterization of these materials showed the formation of novel ionomeric structures with dramatic improvements in the modulus-temperature behavior and also, in some cases, the stress-strain properties. However no change was observed in the glass transition temperature (DSC) of the ionomers when compared with their non-ionic counterparts, which is a strong indication of the formation of blocky structures. 

SMMA Styrene-methyl methacrylate block copolymer sPS Syndiotactic polystyrene S-S Simha and Somcynsky cell-hole theory SSE Single-screw extmder SSSE Solid-state shear extrusion TD Transverse direction TEM Transmission electron microscopy Tg Glass transition temperature THE Tetrahydrofuran TIBA fr -Isobutyl aluminum (°C) Melting temperature TMA fr -Methyl aluminum TMS Trimethylsilyl... 

The physical properties of the acid- and ion-containing polymers are quite interesting. The storage moduli vs. temperature behavior (Figure 8) was determined by dynamic mechanical thermal analysis (DMTA) for the PS-PIBMA diblock precursor, the polystyrene diblock ionomer and the poly(styrene)-b-poly(isobutyl methacrylate-co-methacrylic acid) diblock. The last two samples were obtained by the KC>2 hydrolysis approach. It is important to note that these three curves are offset for clarity, i.e. the modulus of the precursor is not necessarily higher than the ionomer. In particular, one should note the same Tg of the polystyrene block before and after ionomer formation, and the extension of the rubbery plateau past 200°C. In contrast, flow occurred in... 

The novel reaction scheme which we had proposed for "blocky" ionomers through emulsion polymerization prompted us to prepare very well defined ion containing block copolymers through anionic polymerization. The initial system chosen for synthesis, modification, and characterization was the poly-styrene-poly(isobutyl methacrylate) diblock (PS-PIBM DB) copolymer. This particular system was chosen for the following reasons ... 

New macroradicals have been obtained by proper solvent selection for the homopolymerization of styrene, methyl methacrylate, ethyl acrylate, acrylonitrile, and vinyl acetate, and by the copolymerization of maleic anhydride with vinyl acetate, vinyl isobutyl ether, or methyl methacrylate. These macroradicals and those prepared by the addition to them of other monomers were stable provided they were insoluble in the solvent. Since it does not add to maleic anhydride chain ends, acrylonitrile formed a block copolymer with only half of the styrene-maleic anhydride macroradicals. However, this monomer gave excellent yields of block polymer when it was added to a macroradical obtained by the addition of limited quantities of styrene to the original macroradical. Because of poor diffusion, styrene did not add to acrylonitrile macroradicals, but block copolymers formed when an equimolar mixture of styrene and maleic anhydride was added. 

Poly(isobutylene-Woc/c- -caprolactone) copolymer Poly(isobutylene-Woc/c-styrene) copolymer Poly(isobutylene-Woc/c-isobutyl vinyl ether) copolymer Poly(isobutylene-Woc/c-a-methylstyrene) copolymer Poly(isobutylene-block-methyl vinyl ether) copolymer Poly(isobutylene-b/oc/c-methyl methacrylate) copolymer... 

---