Polymer networks are prepared by heat-curing of prepolymers containing cyclic ammonium cations with carboxylate-containing reagents as counter anion.A first part describes the cross-linking of copolymers of N-cyclohexyl-3-azetidinyl methacrylate (CHAM) and methyl methacrylate with hydrogen chloride or mono- or poly-carboxylic acids. Curing temperatures were between 90 and 140 degrees C and curing times between 3 and 20 min, depending on the CHAM-content and the type of acid used.In a second part, pyrrolidinium ion containing (co)polymers were reacted with carboxylate ion containing (co)polymers to form the corresponding inter polymer complexes (IPCs) which were subsequently heat-cured. The first was an IPC obtained by mixing the water-soluble (co)polymer of N,N-diallylpyrrolidinium chloride (DAPC) with sodium acrylate (co)polymer. Heating of the dry IPC film or powder resulted in ring-opening of the pyrrolidinium ions by the carboxylate ions leading to covalent networks. A second type of IPC was obtained by mixing copolymers of N-(vinyl benzyl)pyrrolidine (VBP) with acrylic acid copolymers. The thus obtained IPCs are transformed into covalent polymer networks by curing at 130 degrees C. Also IPCs with different structural units (for ex. VBP-Styrene copolymer with acrylic acid-butyl acrylate copolymer) could be formed and cured leading to polymer-co-networks. (C) 2012 Elsevier Ltd. All rights reserved.

A straightforward strategy for the synthesis and functionalization of polyurethanes (PUs) via the use of alkyne-functionalized polytetrahydrofuran (PTHF) diols is described. The alkyne groups have been introduced into the PTHF chains by the cationic ring-opening copolymerization of tetrahydrofuran and glycidyl propargyl ether. These PTHF prepolymers were combined with 1,4-butanediol and hexamethylene diisocyanate for the synthesis of linear PUs with latent functionalization sites. The polyether segments of the PUs have then been coupled with several types of functionalized azides by the copper-catalyzed azide-alkyne "click'' chemistry, for example with phosphonium containing azides for their antibacterial properties. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 1597-1604, 2011

Polytetrahydrofuran (PTHF)/clay nanocomposites were prepared by two routes: in situ cationic ring opening polymerization (CROP) and a method involving "click" chemistry. In the first method, PTHF chains were grown from the surface of the organo-modified montmorillonite clay by CROP of tetrahydrofuran (THF) through the hydroxyl functions of the clay by using trifluoromethanesulfonic anhydride, in the presence of 2,6-di-tert-butylpyridine as proton trap and dichloromethane as solvent. The polymerizations were affected by the clay content ratios. The living characteristics of the polymerization were demonstrated by the semilogarithmic first order kinetic plot. In the second method, CROP of THF has been performed independently to produce alkyne-functionalized PTHF and the obtained polymers were subsequently anchored to azide-modified clay layers by a "click" reaction. The exfoliated polymer/clay nanocomposites obtained by both methods were characterized and compared by X-ray diffraction spectroscopy, thermogravimetric analysis, and transmission electron microscopy. Compared to the virgin polymer, the nanocomposites exhibited improved thermal stabilities regardless of the preparation method. However, the nanocomposites prepared by the "click" chemistry approach appeared to be thermally more stable than those prepared by in situ polymerization. Moreover, the "click" chemistry method also provided better exfoliation.

In this review, a brief history of the studies on carbocationic polymerizations leading, first, to a better understanding of the mechanisms involved and then more and more to controlled polymerizations, is given and it is discussed why most of the “conventional” polymerization procedures could not be applied to achieve living/controlled polymerizations. Then, the different living systems developed in the 1980–2000 period are described. The application of these new mechanisms for the synthesis of well-defined polymer architectures are reported for the most important types of monomers that can be polymerized by these mechanisms: vinyl ethers, di-substituted olefins and styrenics.

In this paper, the combination of atom transfer radical polymerization (ATRP) of 1-ethoxyethyl acrylate (EEA) and the copper(I) catalyzed “click” 1,3-dipolar cycloaddition reaction of azides and terminal alkynes was evaluated as a method to synthesize diverse amphiphilic copolymer structures. Using the 1-ethoxyethyl protecting group strategy, the application field was broadened with the synthesis of complex polymer structures containing poly(acrylic acid) (PAA) segments. A modular approach has been used: polymers with alkyne functionalities as well as azide functionalities have been synthesized. These polymers were subsequently “clicked” together to yield block copolymers. Furthermore, graft copolymers were synthesized by grafting alkyne-containing polymers onto a polymer backbone with multiple azide functions using the combination of ATRP and “click” reactions.

Glycolysis of nylon-6, in the presence of phosphoric acid at 250 degrees C, leads to a mixture of low molecular weight compounds, HPLC analysis combined with H-1-NMR and mass spectroscopy showed that the main degradation products were ethylene glycol derivatives of caprolactam and linear oligomers. No cyclic oligomers were found. Two types of linear oligomers were found i.e. with free carboxylic acid endgroups and with the carboxylic acid endgroups esterified with ethylene glycol.

Star-shaped poly(tetrahydrofuran) (PTHF) with up to six allyl end groups was prepared by living cationic ring-opening polymerization. A functional initiation system, using allyl alcohol and trifluoromethanesulfonic anhydride, was used, followed by end-capping of the living polymer chains with the multifunctional termination agent tris(2-aminoethyl)amine. In this way, star-shaped PTHF with allyl end groups could be synthesized, with varying molecular weight (6000-20000 g(.)mol(-1)) and number of arms (three to six). Subsequently, the terminal allyl functions were quantitatively transformed into hydroxy groups using a hydroboration procedure. Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) analysis, NMR, and size exclusion chromatography confirmed the controlled synthesis of these reactive star-shaped structures. MALDI-TOF was successfully used to determine the absolute molecular weight and purity of star-shaped polymers. They were further characterized by viscosimetry measurements, and their proper-ties were compared to their linear analogues. For the same molecular weight, the stars had a strong reduced viscosity in solution.

The synthesis of star block co-polymers with polytetrahydrofuran (PTHF) core and poly(tert-butyl acrylate) (PtBA) shell was performed using a dual initiator, 4-hydroxy butyl bromoisobutyrate, by combination of cationic ring-opening polymerization (CROP) and atom transfer radical polymerization (ATRP). The in situ reaction of the hydroxyl groups originating from the dual initiator with trifluoromethane sulfonic anhydride provides a triflate ester initiating group for the CROP of THF PTHF star polymers having three arms with tertiary bromide end groups (PTHF)(3) have been prepared by reaction of living PTHF chains with tris(2-aminoethyl)amine (TAEA) in the presence of 2,2,6,6-tetramethylpiperidine (TMP) as a proton trap. Subsequently, the star polymers were used as macroinitiators for the ATRP of tBA using the CuBr/N,N,N',N",N"-pentamethyldiethylenetriamine (PMDETA) catalyst system to obtain the tri-armed star block copolymers (PTHF-b-PtBA)(3). The polymers were characterized with gel-permeation chromatography (GPC) and H-1-NMR. Both techniques demonstrated the formation of tri-armed star block copolymers.

The colloidal stability of the aqueous dispersions of hydrophobic organic pigments, CuPc and carbon black, stabilized by a wide range of polymer structures based on alkyl vinyl ethers was studied. It was shown that, unlike the homopolymers and the random copolymers, the amphiphilic AB, ABA and BAB block copolymers of MVE with IBVE or ODVE show stabilizing activities that depend on their hydrophilic/hydrophobic balance and polymer architecture. After optimization, the colloidal stabilization is competitive with commercial PEO-PPO block copolymers (Pluronic(R)). It was found that the sedimentation of the dispersions was much faster at a higher temperature, above the LCST of the PMVE-blocks. The loss of the stabilizing activity of the block copolymers correlates with an increase of the hydrophobicity of the treated pigment surface. These properties enable the creation of colloidal dispersions with stabilities that can be tuned as a function of temperature.

The end groups of ABA-triblock copolymers HO-PEO-PPO-PEO-OH, (PEO-poly(ethylene oxide), PPO-poly(propylene oxide)), have been modified with ammonia, ethylene diamine and linear polyethylenimine (LPEI) by substitution of the alpha,omega-ditosyl ester of the triblock copolymer (TsO-PEO-PPO-PEO-OTs) with amines, or by the hydrolysis of the corresponding poly(2-methyl-2-oxazoline) (PMeOx) containing ABCBA block copolymers. The latter block copolymer structures have been obtained by the polymerization of MeOx using TsO-PEO-PPO-PEO-OTs as a macro-initiator. Adding poly(acrylic acid) (PAA) to these (poly)amine terminated blockcopolymers leads to the formation of networks through a combination of PAA-PEO hydrogen bonding and PAA-(poly)amine acid-base reaction. Depending on the number of amino groups at both chain ends of the block copolymer, the corresponding complexes behave as liquids, gels or precipitates. Introduction of as little as 1-5 wt.-% block copolymers H2N-PEO-PPO-PEO-NH2 or H2NCH2CH2NH-PEO-PPO-PEO-NHCH(3)CH(2)NH2 to the system of HO-PEO-PPO-PEO-OH/PAA leads to viscous liquids with strong shear-thickening behavior.

Copolymers with both pH- and thermo-responsiveness were synthesized by free radical copolymerization of N-vinylcaprolactam with small amounts of acrylic acid. The copolymers have been prepared in various solvents and characterized by gel permeation chromatography, Fourier-transform infrared (FTIR) spectroscopy and titration. The phase separation behaviour of these copolymers was studied in water and buffered solutions at a variety of pH values and temperatures by means of attenuated total reflectance FTIR and cloud-point measurements. The aqueous solutions of the copolymers showed a temperature, pH and molecular weight dependent phase-separation behaviour. (C) 2003 Society of Chemical Industry.