Synthesis and characterization of macrocyclic vinyl aromatic polymers

The synthesis and characterization by size exclusion chromatography, liquid chromatography, NMR, matrix‐assisted laser desorption/ionization, thermal analysis, and other techniques of well‐defined and narrow molecular weight distribution macrocyclic polystyrene (PS), poly(2‐vinylpyridine), poly(α‐methylstyrene), poly (2‐vinyl‐naphthalene) (P2VN), and poly(9,9‐dimethyl‐2‐vinylfluorene) (PDMVF) containing a single 1,4‐benzylidene, methylidene, or 9,10‐anthracenylidene unit are reviewed. The absorption and emission spectroscopy of PS, P2VN, and PDMVF is also discussed. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2139–2155, 2006     

A Study of Monodispersed Polydimethylsiloxanes

A series of monodispersed polydimenthylsiloxanes (PDMS) with molecular weights from 3K to 156K were synthesized. The intrinsic viscosity and absolute molecular weight of each monodispersed PDMS was measured and the Mark-Houwink equation for the PDMS series in toluene at 25°C was derived: [eta;]=2.88 × 10^?4 M^0.613. It was proven that the accurate molecular weight determination of polysiloxanes is not possible using polystyrene (PS) standards. It can be achieved either by using a gel permeation chromatographic method with PDMS standards or by a calculation from the Mark-Houwink equation using experimental values of intrinsic viscosity.     

Syntheses and characterizations of poly[2‐(dimethylamino)ethyl methacrylate]–poly(propylene oxide)–poly[2‐(dimethylamino)ethyl methacrylate] ABA triblock copolymers

A novel, near‐monodisperse, well‐defined ABA triblock copolymer, poly[2‐(dimethylamino)ethyl methacrylate]‐b‐poly(propylene oxide)‐b‐poly[2‐(dimethylamino)ethyl methacrylate], was synthesized via oxyanion‐initiated polymerization. The initiator was a telechelic‐type potassium alcoholate prepared from poly(propylene glycol) and KH in dry tetrahydrofuran. The copolymers produced were characterized by Fourier transform infrared, ¹H NMR, and gel permeation chromatography (GPC). GPC and ¹H NMR analyses showed that the products obtained were the desired copolymers, with narrow molecular weight distributions (ca. 1.09–1.11) very close to that of the original poly(propylene glycol). ¹H NMR, surface tension measurements, and dynamic light scattering all indicated that the triblock copolymer led to interesting aqueous solution behaviors, including temperature‐induced micellization and very high surface activity. © 2002 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 624–631, 2002; DOI 10.1002/pola.10144     

Living anionic polymerization of (E)‐1,3‐pentadiene and (Z)‐1,3‐pentadiene isomers

The anionic polymerization of (E)‐1,3‐pentadiene (EP) and (Z)‐1,3‐pentadiene (ZP) together with mixture of the E/Z isomers are investigated, respectively. The kinetic analysis shows that the activation energy for EP (86.17 kJ/mol) is much higher than that for ZP (59.03 kJ/mol). GPC shows that it is the EP rather than the ZP isomer that undergoes anionic living polymerization affording quantitative products of the polymers with well‐controlled molecular weights and narrow molecular weight distributions (1.05 ≤? ≤ 1.09). In addition, THF as polar additive has proved its validity to reduce the molecular weight distribution of poly(ZP) from 1.38 to as low as 1.19. The microstructure and sequence distributions of polypentadiene are characterized by ¹H NMR and quantitative ¹³C NMR. Finally, the distinctive reaction activity of two isomers can be elucidated by two different mechanisms which involve the presence of four forms of zwitterions for EP and the typical [1,5]‐sigmatropic hydrogen‐shift phenomenon for ZP. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2291–2301     

Homo‐ and diblock copolymers of poly(furfuryl glycidyl ether) by living anionic polymerization: Toward reversibly core‐crosslinked micelles

We report the synthesis and characterization of well‐defined homo‐ and diblock copolymers containing poly(furfuryl glycidyl ether) (PFGE) via living anionic ring‐opening polymerization using different initiators. The obtained materials were characterized by SEC, MALDI‐TOF MS, and ¹H NMR spectroscopy and molar masses of up to 9400 g/mol were obtained for PFGE homopolymers. If the amphiphilic diblock copolymer PEG‐block‐PFGE was dissolved in water, micelles with a PFGE core and a PEG corona were formed. Hereby, the hydrophobic PFGE core domains were used for the incorporation of a suitable bismaleimide and heating to 60 °C induced the crosslinking of the micellar core via Diels‐Alder chemistry. This process was further shown to be reversible. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis of end‐functionalized polyethers by phosphazene base‐catalyzed ring‐opening polymerization of 1,2‐butylene oxide and glycidyl ether

For the living ring‐opening polymerization (ROP) of epoxy monomers, the catalytic activity of organic superbases, tert‐butylimino‐tris(dimethylamino)phosphorane, 1‐tert‐butyl‐2,2,4,4,4‐pentakis(dimethylamino)‐2Λ⁵,4Λ⁵‐catenadi(phosphazene), 2,8,9‐triisobutyl‐2,5,8,9‐tetraaza‐1‐phosphabicyclo[3.3.3]undecane, and 1‐tert‐butyl‐4,4,4‐tris(dimethylamino)‐2,2‐bis[tris(dimethylamino)phosphoranylidenamino]‐2Λ⁵,4Λ⁵‐catenadi(phosphazene) (t‐Bu‐P₄), was confirmed. Among these superbases, only t‐Bu‐P₄ showed catalytic activity for the ROP of 1,2‐butylene oxide (BO) to afford poly(1,2‐butylene oxide) (PBO) with predicted molecular weight and narrow molecular weight distribution. The results of the kinetic, post‐polymerization experiments, and MALDI‐TOF MS measurement revealed that the t‐Bu‐P₄‐catalyzed ROP of BO proceeded in a living manner in which the alcohol acted as the initiator. This alcohol/t‐Bu‐P₄ system was applicable to the glycidol derivatives, such as benzyl glycidyl ether (BnGE) and t‐butyl glycidyl ether, to afford well‐defined protected polyglycidols. The α‐functionalized polyethers could be obtained using different functionalized initiators, such as 4‐vinylbenzyl alcohol, 5‐hexen‐1‐ol, and 6‐azide‐1‐hexanol. In addition, the well‐defined cyclic‐PBO and PBnGE were successfully synthesized using the combination of t‐Bu‐P₄‐catalyzed ROP and click cyclization. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis of poly(4‐hydroxystyrene)‐based block copolymers containing acid‐sensitive blocks by living anionic polymerization

Living anionic polymerization of an acetal protected 4‐hydroxystyrene monomer, (4‐(2‐tetrahydropyranyloxy)styrene) (OTHPSt), and the chain extension of the poly(OTHPSt) anion with a variety of monomers including styrene, 4‐tert‐butylstyrene, methacryloyl polyhedral oligomeric silsesquioxane (MAPOSS) and hexamethylcyclotrisiloxane is demonstrated. The P(OTHPSt) homopolymer has a glass transition temperature well above room temperature, which facilitates handling and purification of the protected poly(4‐hydroxystyrene) (PHS). The resulting diblock copolymers have narrow dispersities <1.05. Chemoselective mild deprotection conditions for the P(OTHPSt) block were identified to prevent simultaneous degradation of the MAPOSS or dimethylsiloxane (DMS) block, thus allowing for the first reported synthesis of P(HS‐b‐DMS) and P(HS‐b‐MAPOSS). © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1458–1468     

Diblock copolymers of polystyrene‐b‐poly(1,3‐cyclohexadiene) exhibiting unique three‐phase microdomain morphologies

The synthesis and molecular characterization of a series of conformationally asymmetric polystyrene‐block‐poly(1,3‐cyclohexadiene) (PS‐b‐PCHD) diblock copolymers (PCHD: ～90% 1,4 and ～10% 1,2), by sequential anionic copolymerization high vacuum techniques, is reported. A wide range of volume fractions (0.27 ≤ ?_PS ≤ 0.91) was studied by transmission electron microscopy and small‐angle X‐ray scattering in order to explore in detail the microphase separation behavior of these flexible/semiflexible diblock copolymers. Unusual morphologies, consisting of PCHD core(PCHD‐1,4)–shell(PCHD‐1,2) cylinders in PS matrix and three‐phase (PS, PCHD‐1,4, PCHD‐1,2) four‐layer lamellae, were observed suggesting that the chain stiffness of the PCHD block and the strong dependence of the interaction parameter χ on the PCHD microstructures are important factors for the formation of this unusual microphase separation behavior in PS‐b‐PCHD diblock copolymers. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1564–1572     

Preparation of polymethyl methacrylate with well-controlled stereoregularity by anionic polymerization in an ionic liquid solvent

This study investigates the effect of ionic liquids (ILs) on the anionic polymerization of methyl methacrylate (MMA). Polymethyl methacrylate (PMMA), an isotactic polymer, is prepared by anionic polymerization at a high reaction temperature with an IL that acts as both solvent and additive. The most plausible reaction mechanism is determined using ¹H NMR and Fourier-transform infrared spectroscopy. The electrostatic interaction between MMA and the IL increases the apparent steric hindrance in MMA, resulting in the isotactic PMMA.     

Vesicle formation in aqueous mixture of the cetyltrimetylammonium bromide and an anionic chitosan derivative

The present work aimed at research the physic-chemical properties of the interaction of N-decyl-O-chitosan sulfate (an amphiphilic chitosan derivative, C₁₀-OCHS) with cetyltrimetylammonium bromide (CTAB) by the steady-state fluorescent, static/dynamic surface tension, turbidity and transmission electron microscopy (TEM). The results showed that the complex of C₁₀-OCHS/CTAB had high surface activity and lower critical aggregation concentration. Besides, the C₁₀-OCHS/CTAB could self-assemble into various aggregates like irregular spherical aggregates, vesicles or polydisperse aggregates from lower to higher concentrations of CTAB with a mixed C₁₀-OCHS concentration of 200?mg/L.