THERMODYNAMICS AND CHEMICAL ENGINEERING DATA Chinese Journal of Chemical Engineering, 19(3) 478483 (2011)

Density and Viscosity of Ternary Systems (Poloxamer 188 + Ethanol/ Acetone + Water) at Temperatures from 288.15 K to 308.15 K*

LIU Qian (), ZHANG Songhong (), SHEN Shaochuan (), YUN Junxian () and YAO Kejian ()**State Key Laboratory Breeding Base of Green Chemistry Synthesis Technology, College of Chemical Engineering and Materials Science, Zhejiang University of Technology, Hangzhou 310014, China

Abstract The densities and viscosities of ternary systems (Poloxamer 188 + ethanol/acetone + water) were meas-ured at 288.15, 293.15, 298.15, 303.15, 308.15 K and atmospheric pressure for different mass fractions of Polox-amer 188 (0 to 0.02) in aqueous solution and different solvent volume fractions of ethanol/acetone (0 to 0.3) in Poloxamer 188 aqueous solution. The densities were measured by a pycnometer, while the viscosities were meas-ured using two Ubbelohde capillary viscometers. The correlations of density and viscosity of these ternary systems are obtained by fitting the experimental data at different temperatures, mass fractions and volume fractions. Keywords density, viscosity, ternary system, Poloxamer 188, ethanol, acetone

1 INTRODUCTION

Poloxamer 188 is a nonionic block copolymer chemical surfactant. It is well known to have cytoprotec-tive, rheologic, anti-inflammatory and anti-thrombotic activities combined with minimal toxicity [1]. It also has various therapeutic uses in drug delivery systems [2]. As a steric stabilizer, Poloxamer188 is widely em-ployed in the process of preparing solid lipid nanopar-ticles based on antisolvent precipitation, such as sol-vent injection [3, 4], particle formation by the liquid flow-focusing [5, 6] or together with gas displacing [7]. These methods are based on lipid precipitation from a lipid dissolved organic solvent such as ethanol and acetone, lipid particle formation occurs when lipid solution contacts with a Poloxamer 188 aqueous solu-tion. Furthermore, these ternary systems (Poloxamer 188 + ethanol/acetone + water) also exist in prepara-tion of CS-coated oily nanodroplets [8], as well as in the preparation of other nanoparticles by modified spontaneous emulsification solvent diffusion method [9, 10]. Obviously, in order to prepare these nanoparti-cles with small size and narrow diameter distribution, it is necessary to learn about the process of nanoparti-cles formation as well as mass transfer between Poloxamer 188 aqueous solution and organic solvent of lipid. Therefore it is needed to get the basic proper-ties of these ternary systems.

The density and viscosity are two essential prop-erties that affect mixing and phase separation. How-ever, these data of the ternary systems are rare in lit-erature. In this work, we carry out systematic meas-urements of densities and viscosities of the ternary system (Poloxamer 188 + ethanol/acetone + water) at various temperatures. The mass fraction of Poloxamer 188 in aqueous surfactant solution is from 0 to 0.02, while the volume fraction of ethanol/acetone solvent in Poloxamer 188 aqueous solution is from 0 to 0.3.

Experimental data are correlated with polynomial equations.

2 EXPERIMENTAL

2.1 Materials

Poloxamer 188 was supplied by BASF (China) Co. Ltd. (Shanghai, China) with a purity higher than 99.0% (by mass). The ethanol and acetone were sup-plied with a mass fraction purity better than 0.997. Ultrapure water was prepared by Milli-Q Synthesis (Millipore Co. Ltd, USA), with an electrical resistivity of 18.2 Mcm at 298.15 K.

2.2 Apparatus and procedure

The aqueous solution of Poloxamer188 with dif-ferent mass fraction was prepared using an electronic balance with uncertainty of 0.0001 g and measuring flasks.

The densities were determined by a pycnometer having a bulb volume of about 25 ml. A cleaned and dried pycnometer was weighed on an electronic bal-ance, filled with water, and then immersed in a ther-mostatic bath with 0.1 K. After the water temperature reached the required temperature, the pycnometer was removed from the thermostatic bath, cleaned, dried, and weighed. Through this process, the mass values of water under 288.15, 293.15, 298.15, 303.15, and 308.15 K were measured. By the same method, the mass values of the ternary systems (Poloxamer 188 + ethanol/acetone + water) were also measured. The density of the ternary systems can be calculated by

w w

mm

UU (1)

Received 2010-11-14, accepted 2011-02-25.

* Supported by the National Natural Science Foundation of China (20606031). ** To whom correspondence should be addressed. E-mail: yaokj@zjut.edu.cn

Chin. J. Chem. Eng., Vol. 19, No. 3, June 2011 479

where is the density of the ternary system, w the density of water, m the mass of the ternary system and mw the mass of water. The density of water at each temperature was from the literature [11]. Three runs were made for each sample, uncertainties in density measurements were estimated to be within 1 kgm3 at the 95% confidence interval.

The viscosities were measured using calibrated Ubbelohde capillary viscometer of 0.57 mm or 0.64 mm diameter. (As the measured range was wide, two viscometer of different diameter were needed). The viscometer was calibrated with ultrapure water at temperatures of 288.15, 293.15, 298.15, 303.15, and 308.15 K. The viscosity of water at each temperature was from the literature [11]. The instrument constant of viscometer was measured by the linear relationship between the efflux time and the viscosity of water at different temperatures. A cleaned and dried viscometer filled with the ternary system prepared was immersed vertically in a thermostatic bath for twenty minutes. After the temperature of the ternary system achieved the required temperature, the efflux time of the ternary system was recorded with a digital stopwatch with an uncertainty of 0.01 s. All experiments were made at least twice, the deviation was less than 0.5 s, and the obtained data were averaged. The viscosity of the ter-nary system, , was calculated by

CtK U (2) where t is the efflux time of the ternary system, and C is the instrument constant. The measurements of vis-cosity were the same as described in Ref. [12, 13].

3 RESULTS AND DISCUSSION

In Tables 1 and 2, physical properties of ethanol and acetone are measured and compared to several values in literature to assure that there are no signifi-cant effects due to impurities.

Table 1 Comparison of experimental densities () and viscosities () of ethanol with literature values

/kgm3 /mPas T/K

Exp. Lit. Exp. Lit. 288.15 794 793.69 [14] 1.311 1.3182 [14] 293.15 790 789.7 [15] 1.187 1.2050 [14] 298.15 785 785.25 [16] 1.077 1.0710 [14] 303.15 782 781.3 [17] 0.985 0.9817 [18] 308.15 777 776.50 [16] 0.898 0.895 [17]

Table 2 Comparison of experimental densities () and viscosities () of acetone with literature values

/kgm3 /mPas T/K

Exp. Lit. Exp. Lit. 288.15 794 796.87 [19] 0.335 0.335 [20] 293.15 789 790.02 [21] 0.319 0.321 [21] 298.15 785 785.44 [21] 0.305 0.305 [20] 303.15 779 779.66 [22] 0.289 0.292 [22] 308.15 773 773.91 [19] 0.277 0.279 [20]

Table 3 Experimental densities for the ternary system (Poloxamer 188 + ethanol + water)

/kgm3 /kgm3 288.15 K 293.15 K 298.15 K 303.15 K 308.15 K

288.15 K 293.15 K 298.15 K 303.15 K 308.15 K

0.005 0 1002 1000 999 998 996 0.01 0.10 989 987 986 985 983

0.01 0 1002 1001 999 998 997 0.01 0.15 983 981 980 978 976

0.015 0 1003 1002 1000 999 997 0.01 0.20 978 977 974 972 970

0.02 0 1004 1002 1000 999 997 0.01 0.25 973 971 968 966 963

0 0.05 993 992 991 989 988 0.01 0.30 966 963 961 958 955

0 0.10 987 985 984 983 981 0.015 0.05 993 992 991 989 988

0 0.15 981 979 978 976 974 0.015 0.10 987 986 984 982 981

0 0.20 975 974 972 970 969 0.015 0.15 981 979 978 976 974

0 0.25 971 969 966 965 962 0.015 0.20 976 974 972 970 968

0 0.30 965 963 960 957 954 0.015 0.25 970 967 966 963 960

0.005 0.05 994 993 992 991 989 0.015 0.30 964 962 959 956 954

0.005 0.10 988 987 986 984 983 0.02 0.05 995 994 992 991 989

0.005 0.15 983 981 980 978 976 0.02 0.10 988 986 985 983 982

0.005 0.20 978 976 974 972 970 0.02 0.15 982 981 979 977 976

0.005 0.25 972 970 968 965 963 0.02 0.20 976 975 973 971 969

0.005 0.30 969 966 963 961 958 0.02 0.25 971 969 967 964 962

0.01 0.05 994 993 992 991 989 0.02 0.30 964 962 959 957 955

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A series of experiments were made to determine densities and viscosities of the ternary systems (Polox-amer 188 + ethanol/acetone + water) at temperatures of 288.15, 293.15, 298.15, 303.15, and 308.15 K. The experimental densities and viscosities of the ternary

system (Poloxamer 188 + ethanol + water) are listed in Tables 3 and 4, respectively, and the experimental densities and viscosities of the ternary system (Poloxamer 188 + acetone + water) are listed in Tables 5 and 6, respectively, where T, , are the absolute

Table 4 Experimental viscosities for the ternary system (Poloxamer 188 + ethanol + water)

/kgm3 /kgm3 288.15 K 293.15 K 298.15 K 303.15 K 308.15 K

288.15 K 293.15 K 298.15 K 303.15 K 308.15 K

0.005 0 1.246 1.102 0.970 0.870 0.783 0.01 0.10 1.994 1.701 1.415 1.243 1.098

0.01 0 1.382 1.214 1.077 0.949 0.854 0.01 0.15 2.366 1.989 1.646 1.425 1.242

0.015 0 1.539 1.322 1.171 1.035 0.926 0.01 0.20 2.717 2.254 1.898 1.623 1.373

0.02 0 1.670 1.448 1.270 1.122 1.003 0.01 0.25 3.106 2.560 2.127 1.807 1.559

0 0.05 1.359 1.172 1.029 0.912 0.818 0.01 0.30 3.487 2.820 2.338 1.964 1.686

0 0.10 1.615 1.379 1.197 1.051 0.930 0.015 0.05 1.793 1.536 1.335 1.177 1.043

0 0.15 1.928 1.623 1.390 1.204 1.058 0.015 0.10 2.147 1.803 1.547 1.349 1.185

0 0.20 2.322 1.928 1.588 1.364 1.186 0.015 0.15 2.601 2.170 1.832 1.588 1.342

0 0.25 2.671 2.193 1.835 1.522 1.313 0.015 0.20 2.974 2.439 2.051 1.753 1.477

0 0.30 3.010 2.434 2.019 1.708 1.427 0.015 0.25 3.367 2.727 2.284 1.936 1.660

0.005 0.05 1.483 1.306 1.135 0.999 0.894 0.015 0.30 3.702 2.968 2.466 2.062 1.771

0.005 0.10 1.761 1.511 1.308 1.140 1.010 0.02 0.05 1.966 1.729 1.458 1.277 1.133

0.005 0.15 2.089 1.747 1.513 1.305 1.143 0.02 0.10 2.381 2.002 1.725 1.493 1.277

0.005 0.20 2.452 2.083 1.764 1.479 1.286 0.02 0.15 2.776 2.306 1.968 1.699 1.473

0.005 0.25 2.862 2.356 1.973 1.679 1.404 0.02 0.20 3.162 2.611 2.201 1.873 1.618

0.005 0.30 3.202 2.613 2.174 1.841 1.595 0.02 0.25 3.551 2.900 2.431 2.040 1.757

0.01 0.05 1.627 1.411 1.228 1.087 0.972 0.02 0.30 3.894 3.176 2.633 2.209 1.891

Table 5 Experimental densities for the ternary system (Poloxamer 188 + acetone + water)

/kgm3 /kgm3 288.15 K 293.15 K 298.15 K 303.15 K 308.15 K

288.15 K 293.15 K 298.15 K 303.15 K 308.15 K

0.005 0 1002 1000 999 998 996 0.01 0.10 989 988 986 985 983

0.01 0 1002 1001 999 998 997 0.01 0.15 985 984 982 980 977

0.015 0 1003 1002 1000 999 997 0.01 0.20 980 978 976 973 971

0.02 0 1004 1002 1000 999 997 0.01 0.25 975 972 970 967 964

0 0.05 995 994 992 991 989 0.01 0.30 969 966 963 960 957

0 0.10 990 988 986 985 984 0.015 0.05 995 994 992 991 990

0 0.15 985 983 981 979 977 0.015 0.10 990 989 988 986 984

0 0.20 980 977 975 974 971 0.015 0.15 987 985 983 981 979

0 0.25 975 972 969 967 965 0.015 0.20 981 978 976 974 971

0 0.30 969 966 963 960 958 0.015 0.25 974 972 969 967 964

0.005 0.05 994 993 992 990 988 0.015 0.30 969 967 963 961 959

0.005 0.10 988 987 986 984 983 0.02 0.05 997 996 994 993 991

0.005 0.15 983 982 980 978 976 0.02 0.10 992 991 989 987 985

0.005 0.20 978 976 975 973 970 0.02 0.15 987 985 983 981 979

0.005 0.25 973 971 968 966 963 0.02 0.20 982 980 978 975 973

0.005 0.30 967 965 962 960 957 0.02 0.25 977 974 971 968 966

0.01 0.05 994 993 992 991 989 0.02 0.30 971 968 964 962 958

Chin. J. Chem. Eng., Vol. 19, No. 3, June 2011 481

temperature, mass fraction of Poloxamer 188 in aque-ous solution and volume fraction of ethanol/acetone solvent in Poloxamer 188 aqueous solution, respec-tively. Mass fraction is from 0 to 0.2, and volume fraction is from 0 to 0.3. When value remains un-changed, the density of the ternary systems decreases as value increases, while the viscosity of the ternary systems increases. Moreover, when value remains unchanged, both density and viscosity of the ternary systems increase as value increases.

Polynomial equations [23] are fitted to the ex-perimental data. In the range of this experiment, den-sity can be described as Eq. (3), which follows a linear behavior with temperature, mass fraction and volume fraction, while viscosity can be described as Eq. (4), which follows a quadratic behavior with temperature, mass fraction and volume fraction for the ternary systems,

0 1 2 3TU D D D X D Z (3) 2 2

0 1 2 3 4 52

6 7 8 9

T T

T T

K E E E X E Z E E XE Z E Z E X E ZX

(4)

where 03, 09 are the parameters obtained by regression analysis and given in Table 7.

In order to analyze the performance of the fitted equations, the standard deviation, , the coefficient of determination, R2, relative deviation and absolute av-erage relative deviation (AAAD) are used, which are defined by

1/ 2

2,exp ,cal

1( 1)

n

i ii

Y Y nV

(5) 2

2

,exp ,cal ,exp ,cal1 1 1

2 22 2,exp ,exp ,cal ,cal

1 1 1 1

n n n

i i i ii i i

n n n n

i i i ii i i i

R

n Y Y Y Y

n Y Y n Y Y

(6)

relative deviation ,cal ,exp,exp

i i

i

Y YY (7)

,cal ,exp

1 ,exp

1AAADn

i i

i i

Y Yn Y

(8) where Y can be either density or viscosity, Yi,exp and Yi,cal are the experimental values and the calculated values from the fitted equations, respectively, and n is the number of data points.

Figures 1 to 4 show the relative deviation between the experimental and calculated values of density and viscosity. The density and viscosity measurements are well correlated by Eqs. (3) and (4) in the range of this experiment. In all cases, the coefficients of determination

Table 6 Experimental viscosities for the ternary system (Poloxamer 188 + acetone + water)

/kgm3 /kgm3

288.15 K 293.15 K 298.15 K 303.15 K 308.15 K

288.15 K 293.15 K 298.15 K 303.15 K 308.15 K

0.005 0 1.246 1.102 0.970 0.870 0.783 0.01 0.10 1.643 1.461 1.240 1.095 0.975

0.01 0 1.382 1.214 1.077 0.949 0.854 0.01 0.15 1.781 1.524 1.321 1.160 1.032

0.015 0 1.539 1.322 1.171 1.035 0.926 0.01 0.20 1.896 1.613 1.394 1.225 1.084

0.02 0 1.670 1.448 1.270 1.122 1.003 0.01 0.25 2.020 1.683 1.452 1.269 1.118

0 0.05 1.251 1.095 0.962 0.857 0.772 0.01 0.30 2.092 1.784 1.500 1.312 1.155

0 0.10 1.373 1.191 1.038 0.922 0.827 0.015 0.05 1.648 1.428 1.249 1.104 0.986

0 0.15 1.484 1.288 1.120 0.990 0.881 0.015 0.10 1.783 1.534 1.340 1.180 1.052

0 0.20 1.600 1.374 1.182 1.038 0.922 0.015 0.15 1.901 1.632 1.419 1.245 1.107

0 0.25 1.699 1.450 1.262 1.103 0.981 0.015 0.20 2.070 1.724 1.491 1.305 1.159

0 0.30 1.772 1.512 1.304 1.140 1.005 0.015 0.25 2.161 1.798 1.553 1.355 1.198

0.005 0.05 1.371 1.189 1.048 0.932 0.837 0.015 0.30 2.217 1.894 1.631 1.385 1.221

0.005 0.10 1.505 1.303 1.141 1.012 0.904 0.02 0.05 1.801 1.557 1.364 1.198 1.070

0.005 0.15 1.623 1.401 1.219 1.074 0.957 0.02 0.10 2.011 1.721 1.453 1.276 1.133

0.005 0.20 1.734 1.488 1.290 1.134 1.009 0.02 0.15 2.129 1.817 1.525 1.337 1.183

0.005 0.25 1.833 1.568 1.355 1.187 1.050 0.02 0.20 2.242 1.910 1.605 1.398 1.231

0.005 0.30 1.896 1.614 1.396 1.228 1.083 0.02 0.25 2.332 1.977 1.658 1.449 1.268

0.01 0.05 1.511 1.310 1.153 1.021 0.913 0.02 0.30 2.375 2.022 1.739 1.471 1.293

Chin. J. Chem. Eng., Vol. 19, No. 3, June 2011 482

Table 7 Coefficients of Eqs. (3) and (4), standard deviation, , and coefficient of determination R2 for the ternary systems /kgm3 /mPas

Coefficient Poloxamer188+ ethanol + water

Poloxamer188+ acetone + water

Coefficient Poloxamer188+ ethanol + water

Poloxamer188+ acetone + water

0 1112.0 1122.0 0 141.575 88.837 1 0.379 0.422 1 0.935 0.572 2 123.09 116.23 2 71.349 22.017 3 109.33 192.00 3 362.383 278.987 4 0.0016 0.0009 5 0.355 2.364 6 42.922 139.676 7 1.129 0.874 8 0.2239 0.0661 9 29.616 2.111 1.27 0.97 3.595 1.627 R2 0.990 0.992 0.997 0.998

Figure 1 Relative deviations of densities of the ternary system (Poloxamer 188 + ethanol + water) between the experimental and calculated values (The dashed lines are two absolute average relative deviations)

Figure 2 Relative deviations of densities of the ternary system (Poloxamer 188 + acetone + water) between the experimental and calculated values (The dashed lines are two absolute average relative deviations)

Figure 3 Relative deviations of viscosities of the ternary system (Poloxamer 188 + ethanol + water) between the experimental and calculated values (The dashed lines are two absolute average relative deviations)

Figure 4 Relative deviations of viscosities of the ternary system (Poloxamer 188 + acetone + water) between the experimental and calculated values (The dashed lines are two absolute average relative deviations)

Chin. J. Chem. Eng., Vol. 19, No. 3, June 2011 483

are more than 0.99. The AAAD values of density of the ternary system (Poloxamer 188 + ethanol + water) and the ternary system (Poloxamer 188 + acetone + water) are 0.09% and 0.082%, respectively. The AAAD values of viscosity of the ternary system (Poloxamer 188 + ethanol + water) and the ternary system (Polox-amer 188 + acetone + water) are 1.625% and 0.857%, respectively.

4 CONCLUSIONS

In this paper, the density and viscosity of the ter-nary systems (Poloxamer 188 + ethanol/acetone + water) were measured. The experimental results show that the density decreases while the viscosity increases with the increase of the volume fraction of etha-nol/acetone. Both the density and viscosity increase as mass fraction increases. In the range of this experi-ment, density follows a linear behavior, while viscos-ity follows a quadratic behavior with temperature, mass fraction and volume fraction. The agreement between the experimental and fitted values for the density and viscosity is very good.

NOMENCLATURE

AAAD absolute average relative deviation C instrument constant m mass, g mw mass of water, g n number of data points R2 coefficient of determination T temperature, K t time, s Yi,cal calculated value of density or viscosity Yi,exp experimental value of density or viscosity parameter parameter viscosity, mPas density, kgm3 w density of water, kgm3 standard deviation volume fraction mass fraction

Subscriptscal calculated value exp experimental value w water

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