Novel biodegradable amphiphilic graft copolymers containing hydrophobic poly(ester-carbonate) backbone and hydrophilic poly(ethylene glycol) (PEG) side chains were synthesized by a combination of ring-opening polymerization and “click” chemistry. First, the ring-opening copolymerization of 5,5-dibromomethyl trimethylene carbonate (DBTC) and ε-caprolactone (CL) was performed in the presence of stannous octanoate [Sn(Oct)₂] as catalyst, resulting in poly(DBTC-co-CL) with pendant bromo groups. Then the pendant bromo groups were completely converted into azide form, which permitted “click” reaction with alkyne-terminated PEG by Huisgen 1,3-dipolar cycloadditions to give amphiphilic biodegradable graft copolymers. The graft copolymers were characterized by proton nuclear magnetic resonance (¹H NMR), Fourier transform infrared spectra and gel permeation chromatography measurements, which confirmed the well-defined graft architecture. These copolymers could self-assemble into micelles in aqueous solution. The size and morphologies of the copolymer micelles were measured by transmission electron microscopy and dynamic light scattering, which are influenced by the length of PEG and grafting density. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.

Amphiphilic hyperbranched poly(amino ester)s with hydrophilic multi-ethoxylated triacrylate backbone and hydrophobic long alkyl side chain were firstly synthesized via one pot Michael addition polymerization. The poly-(amino ester) could dissolve in cold water and self-assemble into loose micelle. Under 50–1000 ms bubble, the dynamic surface tension (DST) of the poly(amino ester) aqueous solution (0.5 wt%) still maintained in the range of 32–28 mN/m. The aqueous solutions of poly(amino ester)s with different molecular weights showed the lower critical solution temperature (LCST) in the range of 8–50°C, which could also be tuned by its pH. Capped with hydrophobic groups on the terminal units and partially neutralized with acid, the poly(amino ester)s still kept their stable dynamic surfactant behaviors, indicating promising application.

Polymerization of n-octylallene was successfully carried out using a conventional binary rare earth catalytic system composed of rare earth tris(2-ethylhexylphosphonate) (Ln(P₂₀₄)₃) and tri-isobutyl aluminum (Al(i-Bu)₃) for the first time. The effects of catalyst, solvent, reaction time and temperature on the polymerization of n-octylallene were studied. The resulting poly(n-octylallene) has weight-average molecular weight of 11000, molecular weight distribution of 1.4 and 96% yield under the moderate reaction conditions: [Al]/[Y] =50 (molar ratio), [n-octylallene]/[Y] =100 (molar ratio), polymerized at 80°C for 20 h in bulk. The poly(n-octylallene) obtained consisted of 1,2- and 2,3-polymerized units, and was characterized by FT-IR, ¹H NMR and GPC. Further investigation shows that the polymerization of n-octylallene has some living polymerization characteristics, preparing the polymer with controlled molecular weight and narrower molecular weight distribution.

Novel calix[4]arene-poly(ethylene glycol) crosslinked polymer (CCP) has been synthesized by the polycondensation reaction between a p-tert-butylcalix[4]arene derivative and dihydroxyl capped poly(ethylene glycol) (DHPEG, M_n = 1000) catalyzed by neodymium tosylate. The hydrogel, consisted of 66.9% water and 33.1% CCP, can selectively extract aromatic organic molecules from aqueous solution according to the diameter of the guest molecules, which infers that the diameter of the calix[4]arene cavity is about 5.4 Å and the conformation of calix[4]arene units altered from cone conformation to 1,3-alternate conformation during the polycondensation reaction. Furthermore, CCP can also adsorb naphthalene from gas phase, showing much higher capacity than active carbon does, which may have some potential applications in the field of separation and environment protection. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Summary: The applications of calixarenes in polymer synthesis have been reviewed. Calixarenes have been used as ligands to prepare rare earth calixarene complexes. A series of rare earth calixarene complexes have been synthesized and employed as efficient catalysts for the polymerization of ethylene, styrene, butadiene, propylene oxide, styrene oxide, trimethylene carbonate, and 5,5-dimethyl trimethylene carbonate. On the other hand, the synthesis and characterization of star-shaped polymers with calixarene as core molecules are also described.