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See detailElectrochemistry of N-vinyl-2-pyrrolidone and a non polymerizable analogue
Calberg, Cédric ULg; Kroonen, D.; Mertens, Marc et al

in Polymer (1998), 39(1), 23-29

According to previous studies, the electropolymerization of N-vinyl-2-pyrrolidone fits a cationic mechanism with grafting of the polymer onto the platinum anode. However, this article shows that the ... [more ▼]

According to previous studies, the electropolymerization of N-vinyl-2-pyrrolidone fits a cationic mechanism with grafting of the polymer onto the platinum anode. However, this article shows that the pyrrolidone substituent of N-VP is also involved in the anodic reaction in addition to the polymerizable vinyl double bond. This additional reaction in the potential range of interest was confirmed by the electrochemical oxidation of a non polymerizable analogue of N-VP, i.e. N-methylpyrrolidone. Therefore, at least two mechanisms can contribute to the electrodeposition of a polymer film in a solvent of poly N-VP: electrografting and polymer branching and/or crosslinking by species stemming from the electrooxidation of the pyrrolidone rings. [less ▲]

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See detailMelting and crystallization of poly(vinylidene fluoride) blended with polyamide 6
Liu, Zhehui; Maréchal, Philippe; Jérôme, Robert ULg

in Polymer (1997), 38(20), 5149-5153

Melting and crystallization of poly(vinylidene fluoride) (PVDF) blended with polyamide 6 (PA6) has been studied by differential scanning calorimetry. The melting of PVDF and PA6 is observed over a small ... [more ▼]

Melting and crystallization of poly(vinylidene fluoride) (PVDF) blended with polyamide 6 (PA6) has been studied by differential scanning calorimetry. The melting of PVDF and PA6 is observed over a small temperature range, i.e. 174 to 181 degrees C and 220 to 230 degrees C, respectively, over the whole blend composition. This observation indicates that PVDF and PA6 are immiscible and do not co-crystallize, although evidence for intermolecular interactions between PVDF and PA6 has been previously reported. Crystallinity of PVDF seems to decrease on addition of the first 30 wt% PA6, although this effect is not so different from the experimental errors. Kinetics of non-isothermal crystallization of pure PVDF and PVDF blends containing 20 and 40 wt% PA6 has been investigated. The crystallization rate of PVDF is not influenced by PA6 in the temperature range 138.5-145 degrees C. At lower temperatures, it is, however, adversely affected by addition of PA6. The non-isothermal crystallization data for PVDF are fitted by the Ozawa equation in the temperature range 131-141 degrees C. The Ozawa index, or Avrami exponent, for pure PVDF decreases from 3 to 1 on decreasing temperature. This observation agrees with the nucleation of PVDF crystals which is heterogeneous, and a decrease from 3 to 1 in the growth dimension. The main effect of PA6 is to restrict the decrease of the Avrami exponent from 3 to 2 on decreasing temperature, more likely due to a slower decrease in the growth dimension. PA6 does not contribute to nucleation although it is phase separated. [less ▲]

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See detailD.m.a. and d.s.c. investigations of the β transition of poly(vinylidene fluoride)
Liu, Zhehui; Maréchal, Philippe; Jérôme, Robert ULg

in Polymer (1997), 38(19), 4925-4929

The origin of the beta transition in poly(vinylidene fluoride) (PVDF) is still a pending question. This transition has been studied by dynamic mechanical analysis (d.m.a.) and differential scanning ... [more ▼]

The origin of the beta transition in poly(vinylidene fluoride) (PVDF) is still a pending question. This transition has been studied by dynamic mechanical analysis (d.m.a.) and differential scanning calorimetry (d.s.c.) in dependence on sample annealing and dilution with epsilon-caprolactam (CPL). The beta transition temperature is increased upon annealing and thus influenced by the polymer crystallization. Upon addition of CPL, there is no systematic shift in the beta transition temperature, in contrast to the PVDF crystallinity that increases steadily. A shoulder on the low temperature side of the beta transition peak is also observed as a result of annealing. It is shifted to lower temperatures when CPL is added, consistently with a glass transition. It thus appears that the so-called beta-transition is sensitive to the amorphous material, but in a close relationship with the polymer crystallization. Comparison of the observations by d.s.c, and d.m.a. shows that the broad transition observed for the unannealed samples would result from the overlap of two transitions: the glass transition of the unconstrained amorphous phase and the glass transition of chains constrained by the crystalline phase. This situation can account for the complex dependence of the beta transition on the polymer history. [less ▲]

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See detailSynthesis and characterization of hydrogenated poly[alkylmethacrylate(-b-styrene)-b-butadiene-b-(styrene-b-) alkylmethacrylate] triblock and pentablock copolymers
Yu, Jian Ming; Yu, Yisong; Dubois, Philippe ULg et al

in Polymer (1997), 38(12), 3091-3101

Triblock and pentablock copolymers of the X(Y)B(Y)X type have been synthesized by the sequential living anionic polymerization of butadiene (B), styrene (Y) and alkylmethacrylate (X), respectively. The ... [more ▼]

Triblock and pentablock copolymers of the X(Y)B(Y)X type have been synthesized by the sequential living anionic polymerization of butadiene (B), styrene (Y) and alkylmethacrylate (X), respectively. The diadduct of t-BuLi onto m-diisopropenylbenzene (m-DIB) has been used as a difunctional initiator. Methylmethacrylate (MMA), t-butylmethacrylate (tBMA) and isobornylmethacrylate (IBMA) have been used as precursors of the outerblocks X. The polybutadiene (PBD) midblock that contains ca 42-45% 1,2-units has been selectively hydrogenated into a saturated poly(ethylene-co-1-butene) (PEB) block. The homogeneous hydrogenation catalysis has no deleterious effect on the copolymer integrity. These completely soluble thermoplastic elastomers have been characterized by FT i.r., n.m.r., d.s.c. and d.m.a. The PEB midblock has a low Tg (-50°C) and a small propensity to crystallize. The effect of hydrogenation on the morphology and mechanical properties depends on the outer block. Upon hydrogenation of the PBD midblock in polymethylmethacrylate (PMMA) and polyisobornylmethacrylate (PIBMA) containing triblock copolymers, the ultimate tensile strength is increased (except for a hard block content > 50%) due to a sharper phase separation, whereas the elongation at break is decreased. The extent of phase separation is reduced in polyt-butylmethacrylate(PtBMA) containing triblock copolymers upon hydrogenation and the ultimate tensile strength is slightly decreased. Stereocomplexation of the syndiotactic PMMA outerblocks is observed to occur upon blending with isotactic PMMA [less ▲]

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See detailDesign of polymer blend rheology: 4. Effect of polymethacrylic ionomers on the melt viscosity of polyamide m x D,6
Degée, Philippe; Vankan, R.; Teyssié, Philippe et al

in Polymer (1997), 38(15), 3861-3867

Rheological properties of blends of polyamide m x D,6 (PA) with random copolymers of methyl methacrylate and methacrylic acid (P(MMA-co-MAA)) and the related ionomers (P(MMA-co-metal MA)), respectively ... [more ▼]

Rheological properties of blends of polyamide m x D,6 (PA) with random copolymers of methyl methacrylate and methacrylic acid (P(MMA-co-MAA)) and the related ionomers (P(MMA-co-metal MA)), respectively, have been investigated at 260°C. Addition of small amounts of suitable ionomers (up to 5 wt%) remarkably increases the melt viscosity of PA. At low shear rates and depending on the metal cation of the ionomer, the rheofluidity of PA is reduced by at least two orders of magnitude. The PA melt viscosity increases with the cation as follows: Ni2+ < Ba2+ < Mg2+ < Li+ < Na+ < K+ < Cs+. The major effect is believed to occur when the polymer compatibility is improved to the point where a finely dispersed two-phase system with a low interfacial tension is reached, as a result of strong ion-dipole interactions. Polyblends show a rheothinning behaviour which agrees with the reversibility of H-bonding and dipolar interactions. [less ▲]

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See detailStereocomplexation of sPMMA-PBD-sPMMA triblock copolymers with isotactic PMMA: 1. Thermal and mechanical properties of stereocomplexes
Yu, Jian Ming; Yu, Yi-Song; Dubois, Philippe ULg et al

in Polymer (1997), 38(9), 2143-2154

A novel thermoplastic elastomer consisting of a triblock copolymer (MBM) with outer syndiotactic poly(methyl methacrylate) (sPMMA) blocks associated to an inner polybutadiene (PBD) block has been modified ... [more ▼]

A novel thermoplastic elastomer consisting of a triblock copolymer (MBM) with outer syndiotactic poly(methyl methacrylate) (sPMMA) blocks associated to an inner polybutadiene (PBD) block has been modified by stereocomplexation with isotactic PMMA (iPMMA). Solution cast films of stereocomplexes have been analysed by thermal analysis as a function of the iPMMA/sPMMA (i/s) mixing ratio and the solvent used for the film casting. Although self-aggregation of iPMMA is currently observed, this phenomenon does not occur in solvent cast films of iPMMA with the MBM copolymers. Extent of complexation depends on the i/s mixing ratio and the casting solvent. At a constant i/s ratio, molecular weight of iPMMA has no significant effect on the extent of stereocomplexation. Thermal stability of the stereocomplexes is only affected by the casting solvent, in contrast to tensile strength which is greatly influenced by the mixing ratio of the two PMMA stereoisomers. Tensile strength is increased when increasing amounts of iPMMA are blended with a triblock copolymer of low PMMA content (e.g. 12%). In case of triblocks of high PMMA content (ca. 30% or higher), a low i/s ratio (<l/4) increases the tensile strength, whereas a high i/s mixing ratio (1/2) results in decreasing tensile strength. The same trend is observed for blends of sPMMA-polystyrene (PS)-PBD-PS-sPMMA (MSBSM) pentablock copolymers with iPMMA. [less ▲]

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See detailTriblock copolymer based thermoreversible gels. 1. Self-association of sPMMA end-blocks in o-xylene and viscoelasticity of the gels
Yu, Jian Ming; Jérôme, Robert ULg; Teyssié, Philippe

in Polymer (1997), 38(2), 347-354

Syndiotactic poly(methyl methacrylate) (sPMMA)-polybutadiene (PBD)-sPMMA triblock copolymers, or MBM, have been studied in the presence of o-xylene which is a selective solvent for the central PBD block ... [more ▼]

Syndiotactic poly(methyl methacrylate) (sPMMA)-polybutadiene (PBD)-sPMMA triblock copolymers, or MBM, have been studied in the presence of o-xylene which is a selective solvent for the central PBD block. Syndiotactic PMMA is known to self associate in o-xylene. The central PBD sequence does not prevent the self-association of sPMMA from occurring. Actually, this phenomenon contributes to the stability of the gels formed at room temperature. An endotherm is observed at 35°C, which is responsible for a gel-sol transition. The original solutions have been heated up to 80°C and then rapidly cooled down below 35°C and maintained at 10, 20 and 25°C respectively. The self-association of the sPMMA outer blocks, and thus the liquid-solid transition, have been studied at each of these temperatures. Dependence of the gel viscosity on frequency and temperature effects on viscoelasticity has also been investigated. [less ▲]

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See detailAnionic polymerization of various methacrylates initiated with LiCl-complexed sBuLi
Antoun, S.; Wang, Jin-Shan; Jérôme, Robert ULg et al

in Polymer (1996), 37(25), 5755-5759

A simple alkyl lithium initiator (sBuLi) complexed with LiCl (10 molar equiv.) has been used to initiate the anionic polymerization of various methacrylic monomers, i.e. methyl methacrylate (MMA), tert ... [more ▼]

A simple alkyl lithium initiator (sBuLi) complexed with LiCl (10 molar equiv.) has been used to initiate the anionic polymerization of various methacrylic monomers, i.e. methyl methacrylate (MMA), tert-butyl methacrylate (tBuMA), glycidyl methacrylate (GMA), and dimethyl amino ethyl methacrylate (DMAEMA) in tetrahydrofuran at -78°C. Only the homopolymerization of tBuMA proceeds in a living manner, as evidenced by both the linear plot of experimental molecular weight (Mnexp) vs theoretical ones (Mncal,) (slope % 0.93) and monomer resumption experiments. However, three types of block copolymers, i.e. PtBuMA-b-PMMA, PtBuMA-b-PGMA, PtBuMA-b-PDMAEMA, have been successfully synthesized with a predictable molecular weight, and narrow molecular weight distribution. [less ▲]

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See detailIntermolecular interactions in poly(vinylidene fluoride) and ε-caprolactam mixtures
Liu, Zehui; Maréchal, Philippe; Jérôme, Robert ULg

in Polymer (1996), 37(23), 5317-5320

Mixtures of poly(vinylidene fluoride) (PVDF) and caprolactam (CPL) have been investigated as models for possible cross-interactions between vinylidene fluoride and amide structural units, that might ... [more ▼]

Mixtures of poly(vinylidene fluoride) (PVDF) and caprolactam (CPL) have been investigated as models for possible cross-interactions between vinylidene fluoride and amide structural units, that might account for the very fine phase morphology previously observed in PVDF/polyamide 6 blends. Over the entire composition range, the PVDF/CPL mixtures are monophase above the PVDF melting temperature. From the depression of the PVDF melting point, a negative interaction energy density, B, has been calculated that, however, depends on both temperature and CPL concentration. Mutual solubility of PVDF and CPL and negative B values are consistent with specific intermolecular interactions whose nature is discussed. [less ▲]

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See detailPolyimide foams derived from a high Tg polyimide with grafted poly(α-methylstyrene)
Hedrick, James L; DiPietro, R.; Plummer, C. J. G. et al

in Polymer (1996), 37(23), 5229-5236

A new route to high-Tg, thermally stable polyimide foams has been developed. Foams were prepared by casting microphase-separated graft copolymers comprising a thermally stable main chain, polyimide, and a ... [more ▼]

A new route to high-Tg, thermally stable polyimide foams has been developed. Foams were prepared by casting microphase-separated graft copolymers comprising a thermally stable main chain, polyimide, and a thermally labile graft, poly(α-methylstyrene). The copolymer compositions were designed so that the thermally labile block would be the dispersed phase. This can unzip to its monomer upon heating, and the decomposition product diffuses out of the film, leaving pores embedded in a matrix of the thermally stable component. The copolymers were synthesized through either the poly(amic acid) precursor, followed by chemical cyclodehydration to the imide form, or the poly(amic alkyl ester) precursor followed by thermal imidization. The decomposition of the α-methylstyrene in the block copolymer was studied by thermogravimetric, dynamic mechanical and thermomechanical analyses. Mild decomposition conditions were required to avoid rapid depolymerization of the α-methylstyrene and excessive plasticization of the polyimide matrix. The foams showed pore sizes with diameters ranging from less than 20 nm to over 1 µm, depending upon the synthetic route employed, and the reduction in the mass density was generally consistent with the starting composition. [less ▲]

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See detailA new poly (ε-caprolactone) containing hybrid ceramer prepared by the sol-gel process
Tian, Dong; Dubois, Philippe ULg; Jérôme, Robert ULg

in Polymer (1996), 37(17), 3983-3987

A new inorganic-organic hybrid material, known as ceramer, has been prepared by the sol-gel process. α,ω-Hydroxyl poly(ε-caprolactone) (PCL) has been used as an organic reagent, as such or after ... [more ▼]

A new inorganic-organic hybrid material, known as ceramer, has been prepared by the sol-gel process. α,ω-Hydroxyl poly(ε-caprolactone) (PCL) has been used as an organic reagent, as such or after conversion of the hydroxyl end-groups into triethoxysilane end-groups. The novelty has to be found in the biocompatibility and biodegradability of the organic constitutive component. Since the hydroxyl end-groups of PCL are less reactive than the triethoxysilane counterparts, the preliminary reaction of the hydroxyl end-groups with 3-isocyanatopropyltriethoxysilane is recommended for decreasing the gelation time and the amount of PCL extractable from the final hybrid material. In this respect, it has been observed that the amount of PCL incorporated into the network is limited by the early vitrification of the reactive system. This drawback can be alleviated by curing the sample at a high enough temperature (100°C). TEM observations have shown that the organic and inorganic phases are intimately mixed when the weight composition in SiO2 and PCL is close to 50%. [less ▲]

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See detailLight scattering study of salt-free "polyelectrolyte behaviour" of monotelechelic ionomers in a polar solvent
Kupperblatt, Gary; Hara, Masanori; Vanhoorne, Pierre ULg et al

in Polymer (1996), 37(16), 3741-3744

Salt-free polyelectrolyte behaviour which is typically observed at low polymer concentrations for polyelectrolyte aqueous solutions and random ionomer non-aqueous solutions (in polar solvents) (i.e ... [more ▼]

Salt-free polyelectrolyte behaviour which is typically observed at low polymer concentrations for polyelectrolyte aqueous solutions and random ionomer non-aqueous solutions (in polar solvents) (i.e., negative angular dependence of the reciprocal scattering in static light scattering and an appearance of the fast mode in dynamic light scattering) has been observed for monotelechelic ionomer solutions in a polar solvent. This indicates that only single charge (per chain) is sufficient to produce intermolecular electrostatic interactions, which are responsible for such characteristic behaviour. However, the 'characteristic' behaviour, which is typically observed at higher concentrations for polyelectrolyte and random ionomer solutions (i.e., large positive apparent radius of gyration in static scattering and appearance of the slow mode in addition to the fast mode in dynamic scattering) has not been observed to date for monotelechelic ionomer solutions. The absence of high-concentration characteristics for the monotelechelic ionomer solutions gives additional insight as to the nature and structure of 'heterogeneities' in salt-free polyelectrolyte solutions, which is still controversial. [less ▲]

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See detailBiodegradable and macroporous polylactide implants for cell transplantation : 1. Preparation of macroporous polylactide supports by solid-liquid phase separation
Schugens, Ch; Maquet, Véronique; Grandfils, Christian ULg et al

in Polymer (1996), 37(6), 1027-1038

Freeze-drying of polylactide solutions in 1,4-dioxane has been studied as a way to produce microcellular foams. The thermally induced phase separation has been studied in relation to several processing ... [more ▼]

Freeze-drying of polylactide solutions in 1,4-dioxane has been studied as a way to produce microcellular foams. The thermally induced phase separation has been studied in relation to several processing and formulation parameters. The effects of polymer concentration, chain stereoregularity, polymer molecular weight and cooling rate have been investigated in connection with the porous morphology and the physico-mechanical characteristics of the final foams. As a rule, bundles of channels are formed with a diameter of ~100 μ.m. They have a preferential orientation that fits the cooling direction. A porous substructure (~10 μm) is observed in the internal walls of the tubular macropores. Variations in this general porous morphology-and particularly in the porosity, density, solvent residue, mechanical resistance and degree of regularity in the spatial organization of pores-have been observed when polymer concentration in 1,4-dioxane and polylactide stereoregularity are changed. As expected, cooling rate has a strong effect on the foam morphology, which is essentially controlled by the solvent crystallization. Pores are nothing but the fingerprints of 1,4-dioxane crystallites. [less ▲]

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See detailThe use of styrenic copolymers to generate polyimide nanofoams
Hedrick, James; Hawker, Craig J; DiPietro, R. et al

in Polymer (1995), 36(25), 4855-4866

New routes for the synthesis of high T-g thermally stable polymer foams with pore sizes in the nanometre regime have been developed. Foams were prepared by casting well-defined microphase-separated block ... [more ▼]

New routes for the synthesis of high T-g thermally stable polymer foams with pore sizes in the nanometre regime have been developed. Foams were prepared by casting well-defined microphase-separated block copolymers comprising a thermally stable block and a thermally labile material. At properly designed volume fractions, the morphology provides a matrix of the thermally stable material with the thermally labile material as the dispersed phase. Upon thermal treatment, the thermally unstable block undergoes thermolysis generating pores, the size and shape of which are dictated by the initial copolymer morphology. Several labile blocks were surveyed including polystyrene, poly(alpha-methylstyrene) and several alpha-methylstyrene/styrene copolymers. Each of these polymers can unzip to its monomer upon heating; however, the rate is substantially slower for polystyrene. The copolymers were synthesized through either the poly(amic acid) precursor, followed by chemical imidization to the polyimide form, or the poly(amic alkyl ester) precursor followed by thermal imidization. The decomposition of the labile coblock was studied by thermogravimetric and dynamic mechanical analysis. Upon decomposition, the foams showed pore sizes in the nanometre regime along with the expected reduction in mass density. [less ▲]

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See detailShear thickening of halato-telechelic polymers in apolar solvents
Maus, Christian; Fayt, Roger; Jérôme, Robert ULg et al

in Polymer (1995), 36(10), 2083-2088

Short-length polymers selectively end-capped with a metal carboxylato group at both ends, i.e, metal carboxylato-telechelic polymers, exhibit an unusual shear-thickening behaviour in apolar solvents ... [more ▼]

Short-length polymers selectively end-capped with a metal carboxylato group at both ends, i.e, metal carboxylato-telechelic polymers, exhibit an unusual shear-thickening behaviour in apolar solvents, depending on the main experimental parameters that control the ion-pair association, such as metal cation, concentration and temperature. In contrast to the non-ionic precursors, metal carboxylato-telechelics are indeed responsible for a marked increase in the solution viscosity in a range of shear rates between 0.1 and 1000 s(-1). The shear-rate dependence of the solution viscosity has been analysed in a close relationship to metal counterion, polymer concentration, temperature and addition of polar compounds to the apolar solvent. As a rule, the dilatant behaviour depends strongly on the formation of polymer aggregates in relation to the mutual interactions of the ion pairs. A consensus is now emerging on the origin of the shear-thickening effect, which should be found in inter-aggregate associations rather than in a transition from intramolecular to intermolecular associations of the individual chains. [less ▲]

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See detailCrosslinked polyimide foams derived from pyromellitic dianhydride and 1,1-bis(4-aminophenyl)-1-phenyl-2,2,3-trifluoroethane with poly(α-methylstyrene)
Charlier, Y.; Hedrick, James L; Russel, T. P. et al

in Polymer (1995), 36(6), 1315-1320

A new route for the synthesis of high glass transition temperature, thermally stable polymer foams with pore sizes in the nanometre regime has been developed, using compositionally asymmetric microphase ... [more ▼]

A new route for the synthesis of high glass transition temperature, thermally stable polymer foams with pore sizes in the nanometre regime has been developed, using compositionally asymmetric microphase-separated block copolymers where the minor component (poly(α-methylstyrene)) is thermally labile and the major component (polyimide) is thermally stable. The minor component can unzip to its monomer upon heating, and the decomposition products can diffuse out of the film, leaving behind pores embedded in a matrix of the thermally stable component. In this study, the polyimide block was crosslinked with ethynyl functionalities to obtain a stable porous structure. The decomposition of the α-methylstyrene in the block copolymer was studied by thermogravimetric, dynamic mechanical and thermomechanical analyses. Mild conditions were required to avoid rapid depolymerization of the α-methylstyrene and plasticization of the polyimide matrix. The foams showed pore sizes with diameters up to a micrometre in size as well as the expected reduction in the mass density. However, the crosslinking of the matrix as a means of stabilizing the expected nanofoams was not successful. [less ▲]

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See detailInfluence of the functionality of the quaternizing agent and the polymer molecular weight on the viscoelastic behaviour of α,ω-(dimethylamino)-polyisoprenes
Charlier, Pascal; Agarwal, Pawan K; Jérôme, Robert ULg

in Polymer (1995), 36(6), 1209-1216

Quaternization of the end-groups of α,ω-(dimethylamino)polyisoprenes with monofunctional, difunctional and trifunctional halides (iodides and bromides) has been undertaken on polymers of different ... [more ▼]

Quaternization of the end-groups of α,ω-(dimethylamino)polyisoprenes with monofunctional, difunctional and trifunctional halides (iodides and bromides) has been undertaken on polymers of different molecular weights (Mn = 6000 and 38000 gmol-l). The thermal stability of the ammonium end-groups is somewhat better when iodide counteranions are present. Quaternization increases the T~ of the material. This effect is more pronounced for low molecular weight chains, especially when a short alkyl group quaternizing agent is used. However, the size of the alkyl or aryl radical has a minor effect on polymer Tj when difunctional quaternizing agents are used. Nevertheless, the modulus of the rubber-like plateau of materials with difunctional agents is higher than with monofunctional quaternizing agents, owing to coupling reactions between the chain-ends. Rheological measurements indicate that the quaternized low molecular weight polyisoprenes exhibit an Arrhenius-type temperature dependence characterized by activation energies which vary between 121 and 146kJmol-1 and suggest that the relaxations attributed to dipole-dipole interactions dominate over long chain entanglements. [less ▲]

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See detailMicroencapsulation by coacervation of poly(lactide-co-glycolide): Physico-chemical characteristics of the phase separation process
Stassen, S; Nihant, Nicole; Martin, Véronique et al

in Polymer (1994), 35(4), 777-785

This paper describes the phase separation of different lactide and glycolide copolyester solutions, induced by the addition of silicone oil in order to promote protein microencapsulation. The phase ... [more ▼]

This paper describes the phase separation of different lactide and glycolide copolyester solutions, induced by the addition of silicone oil in order to promote protein microencapsulation. The phase diagrams of the ternary CH2Cl2-copolyester-silicone oil systems were established in relation to the composition of the copolyester and the viscosity, i.e. the molecular weight, of the silicone oil. The phase-separated systems were characterized in terms of weight, volume, composition and viscosity of the coacervation agent (silicone oil) on the characteristics of the phase-separated system is discussed. [less ▲]

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