| 1. |
- Andersson, Markus, 1981, et al.
(författare)
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Vinylimidazole copolymers: coordination chemistry, solubility, and cross-linking as function of Cu2+ and Zn2+ complexation
- 2011
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Ingår i: Colloid and Polymer Science. - : Springer Science and Business Media LLC. - 0303-402X .- 1435-1536. ; 289:12, s. 1361-1372
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Tidskriftsartikel (refereegranskat)abstract
- P(1-VIm-co-MMA) copolymers with 4 or 44 wt.% 1-VIm (abbreviated PVM-4 and PVM-44) where polymerized from 1-VIm (1-vinylimidazole) and methylmethacrylate with azobisisobutyronitrile as initiator and reacted with either Cu(2+) or Zn(2+). The resulting coordinated polymer complexes were studied using ICP-AES, CP/MAS (13)C NMR, conductivity measurements, vibrational spectroscopy (mid-FTIR and far-FTIR), DSC, and EPR. It was established by ICP-AES, CP/MAS (13)C NMR, conductivity, mid-FTIR and EPR measurements that the transition metal ions in the complexes were exclusively coordinated by the imidazole ligand. The coordination geometry is square planar with regard to Cu(II) complexes. The strong interaction between the polymeric imidazole ligand and the transition metal ion cross-links the system, resulting in augmentation of T (g) (the glass transition temperature), especially for copolymers with high relative amount of 1-VIm. The effect of changing metal ion is more complicated and depends on both the strength of the coordinate interaction as well as the coordination number. The solubility of the coordinate polymer complex in conventional solvents is low due to the coordinate cross-links. However, the coordinate polymer complexes are soluble in strongly coordinating solvents such as acetonitrile and dimethylsulfoxide.
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| 2. |
- Andersson Trojer, Markus, et al.
(författare)
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Use of anchoring amphiphilic diblock copolymers for encapsulation of hydrophilic actives in polymeric microcapsules : methodology and encapsulation efficiency
- 2019
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Ingår i: Colloid and Polymer Science. - : Springer Science and Business Media LLC. - 0303-402X .- 1435-1536. ; 297:2, s. 307-313
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Tidskriftsartikel (refereegranskat)abstract
- Aqueous core-shell particles based on polystyrene, poly(methyl methacrylate) or polycaprolactone have been formulated using a facile double emulsion-based solvent evaporation method. The size distribution is narrow, and the morphology control is remarkable given the simple characteristics of the encapsulation method. The inner droplets are stabilized by oil-soluble poly(ethylene oxide)-based block copolymers which are anchored in the polymeric shell by using hydrophobic blocks of the same type as that of the shell-forming polymer. This facilitates the efficient encapsulation of dyes and hydrophilic biocides. [Figure not available: see fulltext.].
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| 3. |
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| 4. |
- Erkselius, Stefan, et al.
(författare)
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A sorption balance-based method to study the initial drying of dispersion droplets
- 2007
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Ingår i: Colloid and Polymer Science. - : Springer Science and Business Media LLC. - 0303-402X .- 1435-1536. ; 285:15, s. 1707-1712
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Tidskriftsartikel (refereegranskat)abstract
- The initial drying of dispersion samples with varying geometries and surface areas was continuously recorded in a sorption balance at different temperatures and relative humidities. The samples were applied as small (5-20 mg) droplets on glass. We were able to show a linear dependence of the evaporation rate on the exposed surface area of the samples if the evaporative cooling was taken into account. The method outlined in the present paper facilitates scaling and comparison of results obtained from drying experiments with different-sized dispersion samples.
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| 5. |
- Ese, M-H, et al.
(författare)
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An atomic force microscopy study of asphaltenes on mica surfaces. Influence of added resins and demulsifiers
- 2000
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Ingår i: Colloid and Polymer Science. - 0303-402X .- 1435-1536. ; 278, s. 532-538
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Tidskriftsartikel (refereegranskat)abstract
- Monolayers of asphaltene and resins on the water surface have been transferred at a surface pressure of 10 mN/m onto mica substrates using the Langmuir-Blodgett technique. Atomic force microscopy (AFM) has been used to examine the topography of these layers. Monolayers consisting of pure asphaltene fraction provide a rigid film with a close packed structure, while the resins build up a continuous open network. Mixed films of these two fractions, show that a gradually increase of resin concentration leads to an opening of the rigid asphaltene structure towards a more resin like configuration. Increased aggregation when the two heavy fractions are present in one film, is seen as larger individual units in the AFM-pictures. Addition of high molecular weight demulsifiers/inhibitors resulted in the same kind of influence on the asphaltene film as seen with the resins.
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| 6. |
- Fundin, J, et al.
(författare)
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The interaction between sodium dodecylsulfate and the cationic-nonionic random copolymer (3-(2-methylpropionamide)propyl)trimethylammonium chloride-acrylamide of two different charge densities studied using dynamic light scattering and rheometry
- 1999
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Ingår i: Colloid and Polymer Science. - 0303-402X .- 1435-1536. ; 277, s. 25-33
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Tidskriftsartikel (refereegranskat)abstract
- The effects of complex formation between sodium dodecylsulfate (SDS) and the positively charged (3-(2-methylpropionamide)propyl)trimethyl-ammonium chloride-acrylamide (MAPTAC-AM) copolymer have been studied in dilute and semidilute aqueous solution in the presence of 10 mM NaCl. Two different charge densities of the copolymer have been used in the study: 0.31 and 0.66, corresponding to the proportion of MAPTAC units. Dynamic light scattering (DLS) and rheometry (static low-shear and capillary viscometry) have been performed on the systems at different charge ratios, i.e., SDS/MAPTAC molar ratios, r. Regarding the phase behavior, the maximum binding ratio prior to precipitation differs between the copolymers. A 1.0% w/v solution of SDS/31% MAPTAC-AM is soluble at r = 0.4 , while an SDS/66% MAPTAC-AM solution of 1.0% w/v shows phase separation at this ratio. With excess surfactant, the complex in the former system is resolubilized at r=2.0, whereas the latter system is still phase-separated at r=5.0. DLS results show that, for both copolymers, the hydrodynamic radius, Rh, of the single-chain copolymer-surfactant complex decreases as a function of r, but then increases slightly prior to phase separation. The corresponding hydrodynamic virial coefficient, kD, changes in the same manner as Rh. The light-scattering data also show that the formation of larger structures is promoted as the polymer concentration is increased from 0.2 to 1.0% w/v. This is shown by the increase in the relative aggregate-to-single coil peak areas in the relaxation time distributions. Both systems have this common trend. The results from rheological measurements support the results from DLS. A reduction in intrinsic viscosity, [], is observed on increasing r up to phase separation. The major part of the static low-shear measurements showed Newtonian behavior for both systems at different copolymer concentrations (27.6-138 mM), and at different r. These systems, partially ionic polymer/oppositely charged surfactant, present very interesting rheological behavior at relatively high polymer concentrations and at low r values. Their behavior is similar to those of hydrophobically modified polyelectrolytes.
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| 7. |
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| 8. |
- Hansen, PHF, et al.
(författare)
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Shear induced aggregation of a pectin stabilised emulsion in two dimensions
- 2001
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Ingår i: Colloid and Polymer Science. - 0303-402X .- 1435-1536. ; 279, s. 153-160
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Tidskriftsartikel (refereegranskat)abstract
- Shear induced aggregation of a Pectin stabilised emulsion trapped at the air-liquid interface was studied in a Couette system by video enhanced microscopy. From dimension analysis, Brownian motion was identified to enhance the probability of bond formation. The characteristic time scale of aggregation was found to scale as tc \sim / rather than tc \sim 1/˙ as expected for orthokinetic aggregation. The structure of very large clusters showed strongly rearranged strands and fractal scaling for low ˙ and , analysed by density auto-correlation. At high ˙ and , the cluster was dominated by larger drops and no fractal scaling could be determined for the accessible length scales.
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| 9. |
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| 10. |
- Johansson, Hans-Olof, et al.
(författare)
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Effect of solute hydrophobicity on phase behaviour in solutions of thermoseparating polymers
- 1997
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Ingår i: Colloid and Polymer Science. - : Springer Science and Business Media LLC. - 0303-402X .- 1435-1536. ; 275:5, s. 458-466
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Tidskriftsartikel (refereegranskat)abstract
- Abstract (1/2-em) Two-phase systems consisting of a polymer rich phase and polymer depleted phase, where the polymer is either ethyl(hydroxy ethyl)cellulose (EHEC) or Ucon (a random copolymer of ethylene oxide and propylene oxide), have been studied. Both of these polymers can be separated from an aqueous solution by either temperature increase or addition of cosolutes. The polymers are thermoseparating and phase separate in water solutions at the cloud point temperature. Two types of EHEC have been studied: one with a cloud point at 60 degreesC and the other at 37 degreesC. The Ucon polymer used in this study has a cloud point at 50 degreesC. Ternary phase diagrams of polymer/water/cosolute systems have been investigated. When a strongly hydrophilic or hydrophobic cosolute is added to an EHEC- or Ucon-water solution, a phase separation occurs already at, or below, room temperature. As cosolutes, hydrophobic molecules like phenol, butyric and propionic acid, and hydrophilic molecules like glycine, ammonium acetate, sodium carboxylates (acetate to valerate), were studied. The polymer rich phase formed when mixing polymer, water and cosolute was strongly enriched or depleted with hydrophobic or hydrophilic cosolutes, respectively. The two phase region increased for propionic acid, butyric acid and phenol as a result of increased cosolute hydrophobicity. The opposite occurred in the series sodium acetate, sodium butyrate and sodium valerate. The effect of temperature on the phase behaviour has also been investigated. Model calculations based on Flory-Huggins theory of polymer solutions are presented, in form of a phase diagram, which semiquantitatively reproduce some experimental results.
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