Hung Anh Nguyen

Cationic polymerization of isobutylene initiated by diol/boron trichloride systems

Cationic polymerizations of isobutylene initiated by 2,5-dimethyl-2,5-hexane diol (HMD) and bis-para-2-hydroxy-2-propylbenzene (BPP)/BCl3 were carried out in CH2Cl2 solution at −30 °C, in presence or in absence of 2,6-ditert-butylpyridine (DtBP).IR, 1H NMR and C13 NMR analysis of the resulting polyisobutylenes (PIB) show the insertion of the diol skeleton in the polymers. GPC chromatograms show that the presence of DtPB prevents protonic initiation. The synthesis of PIB with phenolic end groups was carried out by alkylation of α, ω unsaturated oligoisobutylene in CH2Cl2 at −30 °C initiated by SnCl4. Previously,the alkylation was carried out on a model:2,2,4-trimethyl pentene (TMP). Spectroscopic analyses show that the alkylation takes place mainly on para-position. UV titration of phenyl ring and chemical titration of chlorine show that the functionality of PIB is 2.

A possible “direct initiation” of cationic polymerization of isobutylene by boron trichloride in methylene chloride

SummaryInitiation of the cationic polymerization of isobutylene by BCl3 requires a cocatalyst in most cases. However, we found conditions (θ=-30°C, CH2Cl2 as solvent, BCl3 ⩾ 0.0l m) where a direct initiation by BCl3 (i.e. with no cocatalyst) is possible. We showed that in such conditions HCl is not a cocatalyst and that H2O content is too low to explain the results (high vacuum and highly purified reactants and solvent).The conversion increases linearly with tine increasing concentration of BCl3.A mechanism is proposed.

Analysis of functionalized polyisobutylenes by capillary SFC, SEC, HPLC, and CGC-MS after fraction collection

SummaryAn analytical strategy has been developed for analysis of polyisobutylenes partially functionalized with isothiocyanate groups (

Syntheses of diblock copolymers: poly(2-methylpropene)-b-poly(α-amino acid)

\bar M_n< 2000g mol^{ - 1}

Synthesis of Polymers Containing Pseudohalide Groups by Cationic Polymerization. 14.†Functionalizing “Living” Polymerization of 2-Methylpropene Initiated by the System 1,4-Bis(1-azido-1-methylethyl)benzene/Diethylaluminum Chloride

) by capillary supercritical-fluid chromatography (CSFC), size- exclusion chromatography (SEC), and reversed-phase liquid chromatography (RPLC). Fractions collected from semi-preparative RPLC and SEC were further characterized by capillary GC-MS (gas chromatography coupled with mass spectrometry). Complete characterization of the polymer was achieved by comparing the results obtained from the different techniques. The degree of polymerization and the relative quantity of the different series of macromolecular chains of polyisobutylene were estimated.

Polymerization of 1,3-Pentadiene Initiated by Aluminium Trichloride in Nonpolar Solvent: Pseudo-Control is Explained by Continuous Grafting

The synthesis of end-functionalized oligomers by cationic polymerization is examined. Special attention is devoted to the problem of achieving this synthesis in a one-batch process, starting from the monomer and an additive which is properly functionalized. The functions of interest are chosen among the pseudohalide functions, azide and isothiocyanate. The functionalizing cationic polymerization of 2-methylpropene was the main system discussed in this context. A brief mention about the behavior of 1,3-pentadiene, isobutylvinylether, and 2-methyl-2-oxazoline is presented. It is shown that depending upon the strength of the Lewis acid and the experimental conditions, the specificity of the functionalization and the possibility of a controlled polymerization can be obtained. The experimental observations can be rationalized by assuming an equilibrium between the active species and the dormant chain ends containing a halide or a pseudohalide. This assumption allows to explain the synthesis of polymers containing two different types of chain termini but corresponding to a narrow molecular weight distribution.

Cationic polymerization of dienes. VII. New electron donors in the polymerization of 1,3-pentadiene initiated by aluminum trichloride in non-polar solvent

SummaryDiblock copolymer poly (2-methylpropene)-b-poly (α-amino acid) was obtained by polymerization of the corresponding N-caboxy anhydride initiated by a poly (2-methylpropene) bearing a terminal amine in dioxane/CH2Cl2 mixture. Copolymers were analyzed by FT IR, 1H and 13C NMR.