2.0 4.0 6.0 8.0 10.0 12.0 14.0
Figure 9A: SLES2EO/CAPB system, 10/2 wt/wt, vs. NaCl/Polymer wt/wt ratios. 50 75 222
0/0 1/0 0/0.5 0/1 0.5/0.5 0.65/0.5 0.5/1.0 1/1
NaCl/NL10 Ratio (wt/wt)
SUMMARYThe associative behavior of a new Hyper-HASE polyelectrolyte (INCI: Acrylates/Beheneth-25 Methacrylate Copolymer) in surfactant solutions was studied. Viscosity data indicate that the polymer, which contains a high level of hydrophobic cilia groups, exhibits a unique combination of polyelectrolyte and associative properties. The polymer forms hydrophobic junctions with the surfactant micelles, giving rise to a diversity of polymer-surfactant mesophases. The data indicate that salts such as NaCl or NH4Cl affect the overall structure of the mesophases resulting in 2 to 4 orders of magnitude increase in viscosity with respect to the viscosity of the neat surfactant solutions.
Understanding the interplay between the polymer and surfactants is important since the polymer may affect the rheology and performance of personal care cleansing formulations.
5 6 7 8 9 10 11 12 13 14
Viscosity of Novethix™ L-10 Polymer mucilages
at 0.6 wt% TS and 1 wt% TS depending on the pH
1.0 wt% TS Novethix L-10 Polymer
0.6 wt% TS Novethix L-10 Polymer
Neutralizer: NaOH Viscosimeter: Brook�eld RVT @ 20 rpm, 22°C
Zone AZone B
0 0.5 1.0 1.5
Polymer Concentration, wt%
Critical Overlap Concentration, c*
HYPER-HASE POLYELECTROLYTE SOLUTION PROPERTIES Figure 3A shows that the polymer combines unique associative properties, zone A, and polyelectrolyte properties, zones B and C, as a function of pH and concentration. Figure 3B shows that the polymer is associative exhibiting a typical hydrophobic overlap concentration, c*, at ~0.9 wt%.
In this paper we study the associative properties and rheology of a new anionic Hyper-HASE polyelectrolyte, Figure 2, in aqueous solution and in solutions of nonionic, anionic and zwitterionic surfactants.
INTRODUCTIONHydrophobically modified associative polymers contain attractive groups at the ends of the polymer or along the backbone like the cilia of protozoa, Figure 1. The latter includes polyelectrolytes with pendant hydrophobic groups. Like in the protozoa, the cilia groups allow the polymer to interact with its environment. In solution, they are responsible for intra and inter molecular association, in emulsions they tend to absorb in the oil phase and in surfactant formulations they tend to anchor the surfactant micelles.
CONCLUSIONSThis study explores the unique interaction of a Hyper-HASE polyelectrolyte with various kinds of surfactants in solution. It is shown that the polymer, through its hydrophobic cilia groups, effectively forms junctions with itself and with the surfactant micelles giving rise to the formation of an extended polymer-surfactant network which causes dramatic viscosity increases. It is shown that the polymer-surfactant junctions are stable but may be disrupted at high shear.
Understanding the interaction between the polymer and mixtures of anionic and zwitterionic surfactants is of great practical interest in formulated cleansing products.
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In between pH 6 to 7, the polymer transitions from compact milky, latex-like particles to a swollen state where the solution turns clear, less than 9 NTU, Figure 4.
ASSOCIATIVE BEHAVIOR OF THE HYPER-HASE POLYELECTROLYTE WITH LAURETH-2, C12-(EO)2Figure 5 shows that significant changes occur in the rheological behavior of the solutions indicating that an impressive and rich variety of polymer-surfactant mesophases are formed as a function of surfactant concentration and shear rate.
0 1 2 3 4 5 6 7 8 9 10 Shear Rate, 1/s
Solution viscosity increases with the concentration of Laureth-2
Figure 7: Steady state flow pattern for solutions of the polymer with Laureth-2.
0.001 0.01 0.1 1 10 100 1000
Shear Rate, 1/s
0.2% wt L2
2.0% wt L2
Figure 8: Viscosity of the SLS/CAPB system at 12 wt% total surfactant, SLS/CAPB ratio of 10/2 wt/wt, vs. NaCl/Polymer wt/wt ratios. (Data at pH 6.5 adjusted with NaOH 1M; 25oC; 5% error bars.)
ASSOCIATIVE BEHAVIOR OF THE HYPER-HASE POLYELECTROLYTE IN MIXTURES OF ANIONIC AND ZWITTERIONIC SURFACTANTS Characterizing the rheological behavior of the polymer-surfactant mesophases in mixtures of anionic and zwitterionic surfactants is of great practical importance in formulated products such as shampoos and body washes.
System I. Hyper-HASE polyelectrolyte in solution of SLS and CAPB
Figure 8 shows that adding salt or polymer alone up to 1 wt% results in very small gains in viscosity. However, lofty viscosity gains result upon adding polymer and salt to the surfactant mixture suggesting that large size and stable polymer-surfactant mesophases are synergistically formed.
NaCl/NL10 Ratio (wt/wt)
15 50 175 165
0/0 1/0 0/0.5 0/1 0.5/0.5 0.5/0.75 1/0.5 1/1
Figure 9B: SLES3EO/CAPB system, 10/2 wt/wt, vs. NaCl/Polymer wt/wt ratios. (Data at 12 wt% total surfactant, pH 6.5 adjusted with NaOH 1M, 25ºC; 5% error bars.)
System II. Hyper-HASE polyelectrolyte in mixtures of SLES, SLESnEO n = 2, 3, and CAPB
Figure 9A shows the effect of adding polymer and salt to a mixture of SLES2EO and CAPB. Adding 1 wt% polymer results in viscosity of 14,000 mPa·s. The viscosity trends due to adding salt and polymer resemble System I. However the SLES2EO/CAPB mixture gives higher viscosity.
Figure 9B shows the effect of adding polymer and salt to a mixture of SLES3EO and CAPB. Polymer or salt or a combination of both up to 1 wt%, results in very low viscosity gain. This behavior points to major differences in the morphology of the polymer-surfactant mesophases as result of the higher level of ethoxylation.
10 10 30 960
0/0 1/0 2/0 3/0 0/1 1/1 1/1.5
NaCl/NL10 Ratio (wt/wt)
At very low shear rates the polymer-surfactant mesophases are large and very stable resulting in massive viscosity increases as surfactant is added to the solution, Figure 6A.
0 0.5 1.0 1.5 2.0 Laureth-2, wt%
Shear Rate, 1/s
Figure 6B: Viscosity of the polymer in solution of Laureth-2 at low shear rate.
0 0.5 1.0 1.5 2.0
0.021 0.053 0.068 0.100
Shear Rate, 1/s
Figure 3A: Viscosity of the polymer solution at 0.6 wt% and 1.0 wt% vs. pH adjusted with NaOH 1M.
Figure 2: Structure of the Hyper-HASE polyelectrolyte (INCI: Acrylates/Beheneth-25 Methacrylate Copolymer) where - m, n and p are the moles of methacrylic acid, acrylate and methacrylate esters units, q is the moles of the ethylene oxide and R” is the behenyl radical which constitutes the hydrophobic cilia.
Figure 4: Titration of 1 wt% polymer solution with NaOH 1M at 25°C. pH was recorded on 24-hour-aged solutions.
Figure 5: Flow curves for solutions of polymer and Laureth-2 vs. shear rate.
Figure 1A: Body of Marine Protozoa Trachelocerca Phoenicopterus showing cilia.
Figure 1B: Hydrophobically modified polymer.
Figure 6A: Viscosity of the polymer in solution of Laureth-2 at very low shear rate.
Figure 3B: Viscosity of the polymer as a function of concentration, at pH 7.
At low shear rates, Figure 6B, the morphology of the polymer-surfactant mesophases undergo fascinating changes in shape and size as reflected by the viscosity of the solutions which passes through a maximum and whose position depends on surfactant concentration and shear rate. Furthermore, in Figure 7, two types of polymer-surfactant complexes are apparent below and above 1 s-1. The position of the two maxima is strongly dependent on shear and the concentration of surfactant.
COMPLEX INTERACTIONS OF A HYPER-HASE POLYMER WITH ANIONIC AND NONIONIC SURFACTANTSGalleguillos, R.; Bastos, L.; Culhuac-Vazquez, M.; Mullee, J.
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