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The behavior of a poly(N,N-dimethylacrylamide) hydrophobically modified by incorporating 0.33 mol % of a pyrenyl derivative, [4-(1-pyrenyl)butyl]amine hydrochloride (PY) and 3.56 mol % of dodecylamine (DO) has been studied at the air/water interface. Surface pressure−area isotherm measurements show that the film is initially anchored by the hydrophobic groups at the air−water interface with a pancake-like structure and, with increasing surface pressure, evolves to a quasi mushroom structure, finally reaching a brush configuration at high pressures. Monolayers of this polymer were transferred to silica substrates using the Langmuir−Blodgett (LB) technique at 5, 15, and 25 mN·m^-1. The properties of the LB films were studied by steady-state and time-resolved fluorescence as well as by atomic force microscopy. The results show that the aggregates formed at low pressures are disrupted by pressure increase, while the water-soluble poly(N,N-dimethylacrylamide) becomes dissolved in the water subphase.

A matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI−TOF MS) study of N-acryloylmorpholine (NAM) homopolymers, as obtained by reversible addition−fragmentation chain transfer (RAFT) polymerization technique, is reported. Polymerization of NAM was performed in dioxane using azobis(isobutyronitrile) (AIBN) as initiator and tert-butyl dithiobenzoate as RAFT chain transfer agent. Polymer samples of low molecular weights (<10 000 g mol^-1) and low polydispersity indices (PDI < 1.1) were obtained, which are essential requirements for such MALDI−TOF MS analysis. First, analysis of poly(NAM) samples in linear mode led to %@mt;sys@%%@ob@%%@ital@%M%@rsf@%%@sb@%n%@sbx@%%@obx@%%@mx@% values very close to both size exclusion chromatography/light scattering (SEC/LS) and ¹H NMR values as well as to the theoretical ones. Then, an accurate examination of chain end groups was performed using the reflectron mode. Two main chain populations were identified:  (i) dormant chains (i.e., initiated by a tert-butyl and terminated by a dithiobenzoate group) together with sulfine and thioester-ended chains probably resulting from oxidation of dithiobenzoate chain ends during storage; (ii) proton-terminated chains mainly produced by fragmentation of the former chains in the spectrometer. In addition, some chains which could correspond to termination reactions onto the intermediate radicals involved in the RAFT equilibrium were suspected. Finally, comparison of polymer samples before and after aminolysis indicated that dithioester-ended chains constituted the majority of chains initially present in these samples. This study confirms that it is indeed possible to use MALDI−TOF MS to investigate the structure of polymer chains synthesized by the RAFT technique.

Free-radical solution copolymerization of acrylamide (AAm) and of a disubstituted acrylamide derivative, N-acryloylmorpholine (NAM), with N-acryloxysuccinimide (NAS) was investigated with the aim to obtain a copolymer of at least 100,000 g mol⁻¹. Different polymerization conditions likely to increase the molecular weight were studied such as monomer and initiator concentrations, temperature, and nature of the solvent. The molecular weights were determined by SEC using a light-scattering detector. The grafting of end-functionalized polysaccharide chains onto such high molecular weight poly(NAM-co-NAS) was performed and a graft copolymer bearing a high number of saccharidic branches was obtained. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1808–1816, 2003

Controlled radical polymerization of the bisubstituted acrylamide derivative N-acryloylmorpholine (NAM) has the potential to yield telechelic polymers, one end of which can subsequently be grafted to latex particles. Once grafted, the other chain end of the polymer can be used as an immobilization site for species with applications in molecular biology and biomedicine. The controlled polymerization of NAM using reversible addition−fragmentation chain transfer (RAFT) is performed using two new chain transfer agents S&dbd;C(Z)−SR bearing the same functional propanoic acid group (R) and two different Z groups, benzyl (CTA 1) and phenyl (CTA 2). RAFT polymerization of NAM mediated by CTA 1 is very fast (>80% conversion in less than half an hour at 65 °C). The linear evolution of &Mmacr;n and the low polydispersity indices (&Mmacr;w/&Mmacr;n < 1.2) are in accord with the expected characteristics of a living polymerization. CTA 2 leads to broader &Mmacr;w/&Mmacr;n's (<1.4). The resulting CTA-capped polymers were further used to yield an amphiphilic polyNAM-block-polystyrene. These α,ω-functionalized polyNAM chains were characterized by ¹H NMR and MALDI-ToF mass spectrometry.

The “living” cationic polymerization of a new saccharidic monomer, namely 1,2:3,4-di-O-isopropylidene-6-O-(2-vinyloxyethyl)-d-galactopyranose (GVE) has been investigated using acetaldehyde diethyl acetal/trimethylsilyl iodide as the initiating system in the presence of ZnCl2 as co-initiator. To determine if the process is living, the conversion was followed by dilatometry or by regularly withdrawing samples and analyzing them by ¹H NMR. Fast polymerization occurred together with a nonlinear ln([M]0/[M] t) = f (t) plot indicating an apparent loss of active centers. Nevertheless, the ¹H NMR- and SEC-determined molecular weights proved the absence of termination and transfer reactions during the polymerization process. MALDI−TOF mass spectrometry confirmed the absence of such side reactions and indicated a parallel initiation consecutive to the presence of water traces in the trimethylsilyl iodide solution. The nonlinear ln([M]0/[M] t) = f (t) plot was attributed to specific interactions between the saccharidic rings and ZnCl2 and/or the growing carbocations.

Homopolymers of N-acryloylmorpholine (NAM), a water-soluble bisubstituted acrylamide derivative, have been synthesized by reversible addition-fragmentation chain transfer polymerization (RAFT). Several dithioesters were used as chain transfer agents:  carboxymethyl dithiobenzoate (CMDB), tert-butyl dithiobenzoate (tBDB), menthonyl dithiobenzoate (MDB), and a bifunctional dithiobenzoate, 1,3-bis(2-(thiobenzoylthio)prop-2-yl)benzene (TPB). Whereas CMDB is a commercial reagent, tBDB and MDB were synthesized by a novel biphasic process based on a thioacylation reaction and leading to very high yields. The performances of the four dithiobenzoates were compared in term of kinetics and molecular weight distribution control. Very good control of NAM polymerization was obtained with tBDB and MDB, with a linear increase of Mn vs conversion over the whole conversion range and with polydispersity indices (PDI) below 1.1, as determined by aqueous size exclusion chromatography with on-line light scattering detection. In addition, a degradation phenomenon of the dithioester functions was evidenced during the course of the polymerization, correlated with a Mn vs conversion curve leveling off and even sometimes decreasing above 80% conversion. Such observations were assumed to be the consequence of the formation of side products in the polymerization media, subsequently acting as nondegradative irreversible transfer agents.