Preparation of PMMA macromers by o-vinylbenzylmagnesium chloride and their polymerization

Summary Polymerization of MMA with o-vinylbenzylmagnesium chloride was examined in toluene and in tetrahydrofuran (THF) at various temperatures. The polymer formed in toluene at –78°C was highly isotactic (mm=94%) and containing one vinylbenzyl group at the -end of the chain, although the methanol-soluble fraction concomitantly formed in an appreciable amount was less isotactic. The PMMAs formed in THF at –78 and –98°C were mostly methanol-soluble and highly syndiotactic (rr=88% at –78°C and 96% at –98°C), and also contained one vinylbenzyl group. The methanol-soluble, isotactic and syndiotactic PMMA macromers were polymerized or copolymerized with styrene by AIBN in toluene at 60°C. The isotactic macromer exhibited slightly higher reactivity than the syndiotactic one.     

Stereoregular polymerization of polysiobutylene macromonomer having methacryloyl function

Summary The polysiobutylene (PIB) macromonomer having methacryloyl function was prepared from a hydroxy-terminated PIB, -phenyl--(2-hydroxy-1-methylethyl)-poly(1,1-dimethylethylene) and methacryloyl chloride in the presence of triethylamine. The macromonomer was polymerized by various anionic initiators to form stereoregular polymacromonomers. The polymerization of the macromonomer with t-C₄H₉MgBr and n-C₄H₉Li in toluene gave isotactic polymacromonomers. On the other hand, syndiotactic-rich polymacromonomers were obtained in the polymerizations with 1,1-diphenylhexyllithium in tetrahydrofuran and with t-C₄H₉Li/(C₂H₅)₃Al in toluene.     

PMMA-block-polyisobutylene-block-PMMA prepared with α,ω-dilithiated polyisobutylene and its characterization

Summary A triblock copolymer of PMMA and polyisobutylene(PIB), PMMA-block-PIB-block-PMMA, was prepared by anionic polymerization of methyl methacrylate initiated with , -dilithiated poly(isobutylene) diisobutylate in tetrahydrofuran at -60°C. The molecular weight distribution of the block copolymer was close to that of the starting PIB. The stereoregularity of PMMA block was predominantly syndiotactic. Proton spin-lattice relaxation time and solution viscosity of the block copolymer in acetone, which is non-solvent for PIB, indicate that the block copolymer forms rigid spherical particles. Stereocomplex formation with isotactic PMMA was also studied.     

Highly sensitive self-developing soft X-ray resists of silicon-containing aldehyde copolymers and sensitive novolac-based composite resists containing aldehyde copolymer

Copolymers of aliphatic aldehydes containing a trimethylsilyl group were prepared at ?78°C in toluene using diethylaluminum diphenylamide as an initiator. The copolymer depolymerized into monomeric aldehydes on exposure to soft X-rays. When the copolymer was used as a soft X-ray resist, almost complete development was accomplished by exposure alone. No development step was required. The soft X-ray sensitivity of poly(3-trimethylsilylpropanal-co-propanal) was 50 mJ/cm² at the film thickness of 1.0 μm. A composite resist system consisting of a novolac resin and an aldehyde copolymer containing trimethylsilyl groups has also been developed and used as an alkaline-developable positive electron-beam and soft X-ray resist.     

Asymmetric polymerization of diphenyl-2-pyridylmethyl methacrylate leading to optically active polymer with high one-handed helicity

Summary Diphenyl-2-pyridylmethyl methacrylate (D2PyMA) was polymerized with organolithium complexes of four novel chiral ligands (1–4) which were prepared from (+)-tartaric acid. The complexes of 3 and 4 gave the optically active poly (D2PyMA) with a highly one-handed helical structure. The fractionation of the polymer afforded the poly (D2PyMA) with almost pure one-handed helicity ([] ₃₆₅ ²⁵ -1400^°) in good yield.These chiral lithium complexes were not effective for the asymmetric polymerization of triphenylmethyl methacrylate.     

Stereocomplex formation between isotactic PMMA and syndiotactic polymethacrylates in bulk and in solution

Summary Blend of isotactic PMMA and syndiotactic poly(benzyl methacrylate) was found to form stereocomplex when annealed at 80°C. The blend showed endotherm in DSC thermogram due to the melting of the complex. The complex was also formed in toluene, which was evidenced by¹H NMR spectroscopy and thermal analysis. Several syndiotactic polymers of substituted benzyl methacrylates and aliphatic methacrylates having primary alkyl ester group with branching at -position, such as methallyl and cyclopropylmethyl methacrylates, were also found to form stereocomplexes with isotactic PMMA in bulk by annealing.     

Preparation of highly isotactic and syndiotactic poly(methyl methacrylate) macromonomers having the same chemical structure and their polymerization

Summary Highly isotactic living poly(methyl methacrylate) (PMMA) anion prepared with t-C₄H₉MgBr in toluene at –78°C reacted quantitatively with p-bromomethylstyrene (p-BMST) in the presence of hexamethylphosphoramide or 1,8-diazabicyclo[5.4.0]-undec-7-ene to give the PMMA macromonomer with narrow molecular weight distribution. Highly syndiotactic PMMA macromonomer was also prepared by the reaction of p-BMST and the living PMMA anion formed by t-C₄H₉Li-(n-C₄H₉),Al (Al/Li=3) initiation in the presence of tetramethylethylenediamine. Radical polymerization and copolymerization of these macromonomers were studied in some detail. The results showed the higher reactivity of the isotactic PMMA macromonomer than the syndiotactic one.     

In vitro synthesis of high molecular weight rubber by Hevea small rubber particles

Hevea brasiliensis is one of few higher plants producing the commercial natural rubber used in many significant applications. The biosynthesis of high molecular weight rubber molecules by the higher plants has not been clarified yet. Here, the in vitro rubber biosynthesis was performed by using enzymatically active small rubber particles (SRP) from Hevea. The mechanism of the in vitro rubber synthesis was investigated by the molecular weight distribution (MWD). The highly purified SRP prepared by gel filtration and centrifugation in the presence of Triton^® X-100 showed the low isopentenyl diphosphate (IPP) incorporation for the chain extension mechanism of pre-existing rubber. The MWD of in vitro rubber elongated from the pre-existing rubber chains in SRP was analyzed for the first time in the case of H. brasiliensis by incubating without the addition of any initiator. The rubber transferase activity of 70% incorporation of the added IPP (w/w) was obtained when farnesyl diphosphate was present as the allylic diphosphate initiator. The in vitro synthesized rubber showed a typical bimodal MWD of high and low molecular weight fractions in GPC analysis, which was similar to that of the in vivo rubber with peaks at around 10⁶ and 10⁵ Da or lower. The reaction time independence and dependence of molecular weight of high and low molecular weight fractions, respectively, indicated that the high molecular weight rubber was synthesized from the chain extension of pre-existing rubber molecules whereas the lower one was from the chain elongation of rubber molecules newly synthesized from the added allylic substrates.     

Effect of macrophage colony-stimulating factor (M-CSF) on mouse immune responses in vivo

We examined the effects of recombinant human M-CSF (rhM-CSF) on mouse macrophages and immune responses in vivo. Intraperitoneal administration of rhM-CSF (20-500 microgram/ml) increased Mac-1+ cell numbers in the peritoneal cavity. The tumoricidal activities of the macrophages from vehicle-administered (V-M phi) and from rhM-CSF-administered (M-M phi) mice were the same as those observed in vitro. However, when activated by lipopolysaccharide (LPS), the tumoricidal activity of M-M phi was stronger than that of V-M phi. Intravenous administration of rhM-CSF (500 micrograms/gk) increased the number of spleen cells. Flow cytometric analysis showed that administration of rhM-CSF increased Mac-1+, B220+ and NK 1.1+ cell counts in the spleen. However, CD4+ and CD8+ cell numbers did not change. Concomitant increases were observed in levels of IL-4 and IL-10 in mouse serum following rhM-CSF administration, but no significant changes were observed in the serum level of IFN-gamma. In experiments involving mouse immune responses, the administration of rhM-CSF reduced the contact sensitivity (CS) reaction against picryl chloride (PC) and augmented IgE production in response to 2,4-dinitrophenyl (DNP), but did not affect the production of either IgM or IgC1. These results suggest that administration of rhM-CSF not only activates murine macrophages, but modulates antigen-specific immune responses in vivo.