Phase Behavior for the Poly(phenyl methacrylate) and Phenyl

Article pubs.acs.org/jced

Phase Behavior for the Poly(phenyl methacrylate) and Phenyl Methacrylate in Supercritical Carbon Dioxide and Dimethyl Ether Bong-Seop Lee,† Woon-Hong Yeo,‡ and Hun-Soo Byun*,§ †

Department of Fire and Disaster Prevention Engineering, Kyungnam University, Changwon, Gyeongnam 51767, South Korea Deparment of Mechanical and Nuclear Engineering, Center for Rehabilitation Science and Engineering, Virginia Commonwealth University, Richmond, Virginia 23284, United States § Department of Chemical and Biomolecular Engineering, Chonnam National University, Yeosu, Jeonnam 59626, South Korea ‡

ABSTRACT: Experimental data up to 463.1 K and 269.14 MPa are revealed for binary and ternary mixtures of poly(phenyl methacrylate) [P(PhMA)] + carbon dioxide (CO2) + phenyl methacrylate (PhMA) and P(PhMA) + CO2 + dimethyl ether (DME) systems. The cloud-point pressure for the P(PhMA) + CO2 + PhMA system is measured with the variations of temperature, and PhMA weight fraction of 39.4, 45.8, 54.2, 59.9, and 62.1 wt %. In 62.1 wt % PhMA to the solution of P(PhMA) + carbon dioxide, the cloud-point phase behaviors are shown the typical lower critical solution temperature (LCST). In addition, the effect by cosolvents concentration for the P(PhMA) + CO2 + DME system is investigated at temperature to 453.9 K and pressure range from 52.24 to 80.86 MPa. The cloud point curve for P(PhMA) + CO2 + DME systems is shifted from LCST region to upper critical solution temperature (UCST) region according to the increase of DME concentration. We report experimental data of the PhMA + CO2 system at high pressures range from 6.24 to 24.90 MPa and at several temperatures, that is, 313.2, 333.2, 353.2, 373.2, and 393.2 K. The experimental results are correlated by the Peng−Robinson model with the van der Waals one-fluid mixing rule. Overall, group contributions methods estimate the critical properties for used chemicals in this study.

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INTRODUCTION

dense cosolvent makes the free-volume effect between polymer and solvent reduced.14,15 The goal of this work is the measurement of solubilities for poly(phenyl methacrylate) [P(PhMA)] in low molecular weight SCF solvents (i.e., carbon dioxide (CO2) and dimethyl ether (DME)). The P−T trace of the cloud-point graphs for P(PhMA) + CO2 + phenyl methacrylate (PhMA) and P(PhMA) + CO2 + DME shows a positive and negative slope, respectively. The interchange is characterized by the balance of cross-interactions between polymer segment and solvent molecules and self-interactions of polymer segments and solvent molecules. In addition, strong interactions between polymer segments with the polar functional group16 affect the temperature change, which is related to the interchange. The experimental study of the PhMA + CO2 system focuses on the theoretical investigation by using the Peng−Robinson (PR) model with the van der Waals one-fluid mixing rule where two parameters (kij and ηij) are manipulated. The specific parameters for PhMA such as acentric factor, critical pressure, and temperature are estimated by the Lee and Kesler method and the Joback−Lydersen group contributions method.17

Over the past decades, many studies about the supercritical fluid (SCF) have been published more because the supercritical fluid has been considered as an environmentally favored solvent for many chemical processes. The phase behaviors of polymers in the supercritical fluids give valuable thermodynamic information in various polymer processes used in industry field such as polymerization, fractionation, and material development.1−6 The acrylate- and methacrylate-monomer and polymers consisting of those have been extensively used in various industrial materials such as adhesives, coatings, photopolymer printing plates, prostheses, and contact lenses.7 The understanding of the phase behavior of polymer + supercritical fluids via experimental study provides efficient operation and rational designs. Also, important thermodynamic information can be obtained from the solubility of hydrocarbon solids in supercritical fluid solvents.8−10 Prior experimental works11−13 report the solubility of poly(methacrylate) in SCF solvents at high pressure and various temperatures and the dissolution of poly(methacrylate) with acrylate- and methacrylate-monomer. The cosolvent in SCF solvents is possible to promote the solubility of polymer with high molecular weight in a given solvent owing to several reasons. When the SCF solvent is expanded, the addition of a © XXXX American Chemical Society

Received: February 26, 2017 Accepted: May 17, 2017

A

DOI: 10.1021/acs.jced.7b00220 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Journal of Chemical & Engineering Data

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Article

EXPERIMENTAL SECTION Materials. P(PhMA) (Mw = 100 000; Tg = 383.2 K; CAS RN 25189-01-9) and PhMA (>0.980 mass fraction purity; CAS 2177-70-0) were purchase from Scientific Polymer Products, Inc. and were used without further purification. The molecular structure of PhMA and P(PhMA) are represented in Figure 1.

transferred into the equilibrium cell gravimetrically with the standard uncertainty of 0.004 g. The cloud-point pressure of the mixture was determined with a Heise gauge (Dresser Ind., model CM-108952, 0−345.0 MPa, the standard uncertainty of 0.35 MPa (for polymer + gas + cosolvent system); model CM53920, 0 to 34.0 MPa, the standard uncertainty of 0.03 MPa (for gas + monomer system)) and pressure generator (HIP Inc., model 37-5.75-60 (for polymer + supercritical fluid + cosolvent system), model 68-5.75-15 (for supercritical fluid + monomer system)). The equilibrium cell temperature was detected using a thermometer (Thermometrics Corp., Class A), which is connected to a digital multimeter (Yokogawa, model 7563, the relative standard uncertainty of 0.005%). The temperature in equilibrium cell remained constant within ±0.12 K accuracy using magnetic stirring bar. The equilibrium cell inside was visible through the video monitor using a camera coupled to a borescope (Olympus Corp., model F100-038-00050) placed against the outside of the sapphire window. Light was transmitted into the cell with a fiber optic cable connected at one end to a high-density illuminator (Olympus Optical Co., model ILK-5) and at the other end to a borescope. The various thermodynamic properties such as bubble-point (BP), dew-point (DP), and critical-point (CP) were measured for the PhMA + CO2 mixture. The solution in the view cell is compressed to be a supercritical fluid at a given temperature. The solution with single phase in equilibrium cell maintained for at least 30 to 40 min to reach an equilibrium state. The pressure is then slowly decreased until phases separation happens. A BP is determined when the first bubble of small vapor is formed in the cell, while a DP is determined when a fine mist starts to be generated. The phase transition is a mixture critical point if critical opalescence is observed during the transition process and/or if two phases of equal volume are present when the mixture phase separates. The uncertainties of pressure, temperature and mole fraction were less than u(p) = 0.2 MPa, u(T) = 0.2 K and u(x) = 0.0008, respectively.22,23 A mixture of homopolymer + solvents + monomers in the equilibrium cell was heated to the requested temperature and pressurized until the one-phase. This solution at constant temperature and pressure was maintained for at least ∼30 to 40 min, such that the cell could reach the thermal equilibrium. Afterward, the pressure was slowly decreased until the solution became cloudy. The cloud-point pressure was individuated as the point by not seeing the stir bar anymore in solution. The solution was recompressed into single phase for measuring the cloud-point again, and such process was repeated. Cloud-points for ternary system were obtained at a fixed P(PhMA) weight fraction of about 5.0 wt %. The standard uncertainty of pressure and temperature was less than u(p) = 0.40 MPa and u(T) = 0.2 K, respectively.23,24

Figure 1. Molecular structure of (a) phenyl methacrylate (b) poly(phenyl methacrylate).

To prevent the polymerization of PhMA monomer, 2,6-di-tertbutyl-4-methyl phenol (Aldrich, >0.990 mass fraction purity) was used as an inhibitor with 0.005 times lower concentration than the amount of PhMA. Carbon dioxide (>0.999 mass fraction purity; CAS RN 124-38-9) was acquired from Daesung Industrial Gases Co., and dimethyl ether (>0.995 mass fraction purity; CAS RN 115-10-6) was obtained from E1 Co. The specific properties of all chemicals used in this work are summarized in Table 1. Table 1. Specifications for Used Chemicals chemicals

source

CO2 DME phenyl methacrylate poly(phenyl methacrylate)c

Deok Yang Co. E1 Co. Scientific Polymer Products, Inc. Scientific Polymer Products, Inc.

mass fraction puritya

purification method

analysis methoda

>0.999 >0.995 >0.980

none none none

GCb GCb

none

a

Both analysis method and mass fraction purity are provided by the suppliers. bGas−liquid chromatography. cMw = 100,000; Tg = 383.2 K

Experimental Apparatus and Method. The high pressure equilibrium cell with the static type of variable-volume view cell is used to determine the cloud-point pressure and bubble point. Details of the process are described in previous reports.18−21 The high-pressure measurement system is used to obtain cloud-point pressure curves for P(PhMA) + CO2 + PhMA, P(PhMA) + CO2 + DME,18,19 and CO2 + PhMA systems.20,21 Initially, a certain amount of polymer was loaded into the equilibrium cell with the standard uncertainty of 0.002 g. Afterward, the cell was purged with nitrogen and supercritical fluid solvents to make all of the organic compounds remove. The cosolvent in liquid state was added into the equilibrium cell with the standard uncertainty of 0.002 g using a glass syringe, and supercritical solvent in the high-pressure bomb is

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RESULTS AND DISCUSSION The various properties of used chemicals (i.e., CO2 and DME) such as critical temperature (Tc), critical pressure (pc), critical density (ρc), acentric factor (ω), polarizability (α), dipole moment (μ), and quadrupole moment (Q) are reported in

Table 2. Specific Properties for CO2 and DME solvents

Tc (K)

pc (MPa)

ρc (kg·m−3)

α × 1018 (m3)

μ × 1025 (J·m3)1/2

Q × 1035 (J1/2·m5/2)

CO2 DME

304.1 400.0

7.38 5.30

469 258

2.65 5.22

0.00 4.11

−13.60 3.73

B



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Table 2.17,25,26 DME with a significant dipole moment has stronger dipole−dipole interactions than quadrupole−quadrupole interactions of alkenes and CO2. CO2 has commonly been used to generate a supercritical fluid due to the low critical temperature and pressure as can be seen in Table 2. At temperatures little above room temperature, it is expected to obtain many good properties of a supercritical fluid. Phase Behavior for the P(PhMA) + CO2 + PhMA Mixtures. The phase behavior of ternary system for P(PhMA) + CO2 + DME and P(PhMA) + CO2 + PhMA mixture is measured and is reproduced at least twice with the standard uncertainty of u(p) = 0.40 MPa and u(T) = 0.2 K. The cloud-point phase behavior of the P(PhMA) + CO2 + x wt % PhMA system is represented in Figure 2 and is reported

Table 3. Experimental Cloud-Point for P(PhMA) + CO2 + PhMA Mixture Ta/K

pa/MPa

4.9 wt % P(PhMA)+ 39.4 wt % PhMA 379.0 269.14 402.5 198.28 423.5 164.66 433.7 148.79 445.9 138.79 463.1 130.52 5.1 wt % P(PhMA) + 45.8 wt % PhMA 335.7 137.41 354.2 117.24 373.7 105.70 392.8 98.45 412.7 94.14 433.9 91.03 454.2 88.38 4.9 wt % P(PhMA) + 54.2 wt % PhMA 334.5 41.72 354.4 43.10 374.6 45.10 395.0 47.00 413.9 48.79 432.9 50.52 453.3 52.41 5.1 wt % P(PhMA) + 59.9 wt % PhMA 334.4 11.55 354.6 16.03 372.7 20.17 392.6 24.31 413.2 27.59 432.8 31.21 453.6 33.97

Figure 2. Experimental cloud-point curves for the P(PhMA) + CO2 + x wt % PhMA system according to the concentration of PhMA monomer. The concentration of polymer is about 5.0 wt % for all systems; PhMA: maroon inverted triangle, 39.4 wt %; green triangle, 45.8 wt %; blue square, 54.2 wt %; red circle, 59.9 wt %.

in Table 3. P(PhMA) does not dissolve in pure CO2 up to 463 K and about 280 MPa. The cloud pressure curve of the P(PhMA) + CO2 + 39.4 wt % PhMA according to the increase of temperature shows a minus slope in the cloud-point temperature range of 379.0−463.1 K and cloud point pressure up to 269.14 MPa that shows the upper critical solution temperature (UCST) type. The smooth rise in the cloud-point pressure according to the decrease of temperature results from the increase of interactions between small molecules (i.e., solvent and cosolvent) over the interactions between small molecules and polymer. When 45.8 wt % PhMA is injected into the solution, the cloud-point curve exhibits UCST phase region with linear minus slopes. The ternary system of the P(PhMA) + CO2 + 45.8 wt % PhMA does dissolve at less than pressure of 137.41 MPa and at less than temperature of 454.2 K. When adding 54.2 and 59.9 wt % PhMA to the solution, the lower critical solution temperature (LCST) phase behavior with a linear plus slope is observed. The LCST behavior in the cloudpoint pressure with decreasing temperature is attributed to the much stronger interactions between molecules of different species than between molecules of same species. The cloudpoint curves for those two systems show a linearly plus gradient at about 0.09 MPa/K (54.2 wt %) and 0.17 MPa/K (59.9 wt %), respectively. The effect of PhMA monomer with 62.1 wt % on the phase behavior of the P(PhMA) in supercritical CO2 fluid is investigated, and the experimental data are reported in Table 4. The measured cloud-point pressure curve shows the LCST phase behavior as shown in Figure 3 When system temperature

a

Standard uncertainties u of temperature and pressure are 0.20 K and 0.40 MPa, respectively.

Table 4. Experimental Cloud-, Bubble-Point, and Liquid− Liquid−Vapor Data for the P(PhMA) + CO2 + 62.1 wt % PhMA Mixture Ta/K

pa/MPa

transition

5.4 wt % P(PhMA) + 62.1 wt % PhMA 413.8 436.5 452.0 335.3 354.1 373.1 393.3 423.5

Cloud-Point Transition 21.21 25.35 27.76 Bubble-Point Transition 9.83 12.76 15.35 17.76 Liquid−Liquid−Vapor 21.82

CP CP CP BP BP BP BP LLV

a


is 393.2 K, the phase border has moved from 27.6 to 21.2 MPa with the increase of the concentration of PhMA from 59.9 wt % to 62.1 wt %. The single-phase fluid curve for P(PhMA) + CO2 + 62.1 wt % PhMA system changes to two-phase fluids (vapor and liquid) curve up to approximately 410 K and 20 MPa. An C



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Table 5. Experimental Cloud-Point Data for P(PhMA) + DME + CO2 Mixture Ta/K 5.0 334.7 353.2 373.3 391.7 413.0 434.3 455.1 4.9 336.5 354.5 374.4 394.6 413.6 422.3 3.9 339.6 354.6 376.0 391.9 415.1 433.8 4.6 338.0 355.3 373.1 391.6 411.6 435.4 4.2 334.6 353.7 373.7 394.8 413.0 431.9 453.9

Figure 3. Effect of 62.1 wt % PhMA monomer (on a polymer-free basis) on the phase behavior of the P(PhMA) + CO2 system. The solid circles (red, circle) represent the transition from one fluid phase to liquid + liquid two phases, and the closed square (blue, square) represent the transition from one fluid to liquid + vapor two phases. The dashed line (green, diamond) is the suggested extension of the LLV curve. The concentration of polymer is about 5 wt %.

LV (liquid plus vapor) phase coexists at less than this point, while the LV behavior changes to a LLV (liquid plus liquid plus vapor) region at above this temperature and pressure. At much higher pressure than at this point, the P(PhMA) + CO2 + 62.1 wt % PhMA systems show the LCST cloud-point behavior with linear plus slope of 0.17 MPa/K. From the above-mentioned experimental results, it is demonstrated clearly that a fluid phase can extend over the proper pressures when the free PhMA monomer are presented sufficiently in the P(PhMA) solution in supercritical CO2. Phase Behavior for the P(PhMA) + CO2 + DME Mixtures. Figure 4 and Table 5 present the P−T curve of

pa/MPa wt % P(PhMA) + 79.0 wt % DME 147.41 127.76 111.2.1 106.72 97.41 91.21 86.38 wt % P(PhMA) + 84.7 wt % DME 80.86 80.17 79.48 79.48 79.48 79.48 wt % P(PhMA) + 91.3 wt % DME 58.28 59.48 62.41 64.68 67.24 69.31 wt % P(PhMA) + 91.8 wt % DME 52.24 53.79 56.38 58.45 61.38 64.83 wt % P(PhMA) + 95.8 wt % DME 52.41 55.35 57.41 60.17 62.07 63.97 66.21

a


injected into the solution, the LCST cloud-point behavior with a slightly plus slope at 338.0−435.4 K is observed. Also, the phase behavior of the P(PhMA) + CO2 + 91.3 and 91.8 wt % DME system shows a LCST slope up to 70 MPa. The P−T curves for those systems are linear plus gradient at about 0.12 MPa/K for 91.3 wt % DME and 0.13 MPa/K for 91.8 wt % DME. As can be seen in Table 2, the increases of DME concentration resulted in the dipole moment and the polarity. Note that the cloud-point curve of P(PhMA) in pure DME is located at higher pressures than that of the P(PhMA) + CO2 + 91.8 wt % DME mixture. A mixed (co)solvent of CO2 and DME up to 91.8 wt % DME is more effective in enlarging the miscibility region than either pure solvent alone. The cloudpoint curve reaches a minimum pressure with increasing DME concentration. Apparently, there is a balance between DME + P(PhMA) and polar DME + DME interactions. Phase Behavior for the PhMA + CO2 System. The experimental data for the CO2 + PhMA system have not been given yet in any literature. Experimental phase behavior data on

Figure 4. Effect of DME concentrations on the P(PhMA) + CO2 + x wt % DME systems. The concentration of polymer is about 5 wt % for each solution; DME: red circle, 79.0 wt %; blue square, 84.7 wt %; lime triangle, 91.3 wt %; green inverted triangle, 91.8 wt %; maroon diamond, 95.8 wt %.

the DME effect on the P(PhMA) under supercritical CO2. The phase behavior of the P(PhMA) + CO2 + 79.0 wt % DME solution presents the negative slope at the cloud-point temperature range of 334.7−455.1 K and the cloud-point pressure range of 86.38−147.41 MPa. With 84.7 wt % DME added to the mixture, the P−T curve for the P(PhMA) + CO2 + 84.7 wt % system presents the almost flat slope over the temperature range of 336.5−422.3 K and pressure range of 79.48−80.86 MPa. When the 91.3 and 91.8 wt % DME are D



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Table 6. Experimental Data for the CO2 + PhMA system phenyl methacrylate mole fraction

pressurea/MPa

phenyl methacrylate mole fraction

transition

a

T /K = 313.2 0.036 0.052 0.057 0.063 0.084 0.098 0.118 0.136 0.188 0.248 0.317 0.385 0.446 0.528 0.594

9.74 9.88 9.86 9.85 9.75 9.65 9.43 9.23 8.92 8.69 8.38 7.83 7.31 6.72 6.24

BP BP BP BP BP BP BP BP BP BP BP BP BP BP BP

14.83 15.13 15.33 15.50 15.50 15.47 15.36 15.14 14.28 13.31 12.41 10.83 10.14 8.70 7.81

DP DP DP CP BP BP BP BP BP BP BP BP BP BP BP

18.10 18.90 19.10 19.35 19.30 19.30 19.16 18.93 18.41

DP DP DP DP BP BP BP BP BP

0.248 0.317 0.385 0.446 0.528 0.594

17.41 15.21 13.17 12.00 10.52 9.17

BP BP BP BP BP BP

20.17 22.00 22.41 22.63 22.81 22.81 22.78 22.59 21.83 19.79 18.10 15.66 13.97 12.00 10.40

DP DP DP DP CP BP BP BP BP BP BP BP BP BP BP

21.17 23.08 23.62 23.70 24.10 24.46 24.88 24.90 24.45 22.48 20.59 17.79 15.88 13.67 11.93

DP DP DP DP DP DP DP CP BP BP BP BP BP BP BP

T/K = 373.2 0.036 0.052 0.057 0.063 0.084 0.098 0.118 0.136 0.188 0.248 0.317 0.385 0.446 0.528 0.594 T/K = 393.2 0.036 0.052 0.057 0.063 0.084 0.098 0.118 0.136 0.188 0.248 0.317 0.385 0.446 0.528 0.594

T/K = 353.2 0.036 0.052 0.057 0.063 0.084 0.098 0.118 0.136 0.188

transition

T/K = 353.2

T/K = 333.2 0.036 0.052 0.057 0.063 0.084 0.098 0.118 0.136 0.188 0.248 0.317 0.385 0.446 0.528 0.594

pressurea/MPa

a

Standard uncertainties u are u(T) = 0.2 K, u(p) = 0.2 MPa, and u(x) = 0.0008.

The measured experimental data for PhMA and CO2 system are correlated by using the Peng−Robinson (PR) equation of state (EoS)28 that is defined as follows

the PhMA in supercritical CO2 were reported in Table 6. The standard uncertainties were estimated to pressure at u(p) = 0.2 MPa, temperature at u(T) = 0.2 K and PhMA mole fraction at u(x) = 0.0008.22,23 To the best of our knowledge, no report shows experimental data for the CO2 + PhMA system. Figure 5 and Table 6 show the experimental bubble- and dew-point pressures with the composition of PhMA monomer at given temperatures (313.2, 333.2, 353.2, 373.2 and 393.2) K are distributed at the pressure ranges from 6.24 to 24.90 MPa for the (PhMA + CO2) system. Three phases (i.e., LLV) were not observed in the measured temperature range. The mixturecritical pressures showed the continual increase as the temperature increased, and such tendency is anticipated a type-I phase diagram14,27 with the simplest behavior. The solubility of CO2 in PhMA component decreases according to the increase of temperature at fixed pressure (see in Figure 5).

P=

a(T ) RT − V−b V (V + b) + b(V − b)

a(T ) = 0.457235

b = 0.077796

E

α(T )R2Tc2 pc

(1)

(2)

RTc pc

(3)

α(T ) = [1 + κ(1 − Tr0.5)]2

(4)

κ = 0.37464 + 1.54226ω − 0.26992ω 2

(5)



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and ηij) for the binary system of the PR EoS were obtained by fitting the experimental results at 353.2 K. The binary interaction parameters of the PR EoS for the (PhMA + CO2) system was kij = 0.050 and ηij = −0.052 (number of experimental data = 15, RMSD = 2.38%). Figure 6 represents the experimental and calculated results at the temperatures of T = 313.2, 333.2, 353.2, 373.2, and 393.2 K

Figure 5. Comparison of experimental and calculated values for CO2 + PhMA mixture using PR EoS with kij and ηij stetted to be zero (blue solid lines), and kij = 0.050, ηij = −0.052 (red solid lines/red circle) at 353.2 K.

and the following a van der Waals one-fluid mixing rules are used. amix =

∑ ∑ xixjaij i

aij = (aiiajj)1/2 (1 − kij)

bmix =

Figure 6. Comparison of experimental (symbols) and calculated (solid line) values for CO2 + PhMA systems at different temperatures; maroon diamond, 313.2 K; green inverted triangle, 333.2 K; lime triangle, 353.2 K; blue square, 373.2 K; red circle, 393.2 K.

(6)

j

(7)

∑ ∑ xixjbij i

for the (PhMA + CO2) system using the interaction parameter kij and ηij values estimated at 353.2 K. The calculated values were well-fitted by the PR EoS for the (PhMA + CO2) system (number of experimental data = 75, RMSD = 3.44%). The curves predicted by the PR EoS did not display vapor−liquid− liquid (three) phases at the five temperatures. Figure 7 shows the mixture-critical curves of both experimental data (closed squares) and predicted values

(8)

j

1 (bii + bjj)(1 − ηij) (9) 2 where aii, ajj, bii, and bjj are pure component parameters for each component, and kij and ηij are adjustable parameters between two component (i and j) estimated by fitting the pressure− concentration (p−x) isotherms experimental data. The OF (objection function) and RMSD (root mean squared relative deviation) (%) were defined by bij =

⎛ Pexp − Pcal ⎞2 ⎟⎟ OF = ∑ ⎜⎜ P ⎝ ⎠ exp i N

RMSD (%) =

(10)

OF × 100 ND

(11)

where Pexp, Pcal, and DN mean the pressure value of experiment and calculation, and the number of experimental data, respectively. The pure properties used in the calculation with PR EoS are reported in Table 7. The boiling points (Tb) of PhMA monomer is found in the literature29 and the critical properties are estimated using the Joback-Lyderson method by group contribution.17 The pure saturated vapor pressure is obtained from Lee-Kesler method.17 Figure 5 illustrates the comparison of experimental values for the (PhMA + CO2) system and estimated values with the PR EoS at temperature of 353.2 K. The interaction parameters (kij

Figure 7. Comparison of critical pressure for CO2 + PhMA system. Solid lines and circles (blue) indicate the vapor−liquid lines and critical points (red squares are mixture critical points) for each pure component. Dashed lines (red) represent the predicted values using PR EoS with kij = 0.05 and ηij = −0.052.

Table 7. Specific Properties for Pure Components

a

compound

Mw

structure

carbon dioxide PhMAa

44.01 162.19

OCO H2CC(CH3)COOC6H5

Tb/K

Tc/K

pc/MPa

ω

545.2−546.6b

304.2 784.8

7.38 3.11

0.225 0.457

Phenyl Methacrylate. bAlfa Aesar Co. F



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(dashed line) with PR EoS with adjusted interaction parameters (i.e., kij = 0.050 and ηij = −0.052). The predicted mixturecritical curve is type-I region. Solid lines in Figure 7 represent the saturated vapor pressure of pure components, and the closed circles notify the critical point. The upper region of critical pressure trajectory (dashed line) is one phase (fluid), while the lower region is two phases (vapor−liquid) region.

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CONCLUSIONS In this study, we measure the cloud-point pressure for the ternary system of P(PhMA) + CO2 + PhMA and P(PhMA) + CO2 + DME mixtures according to the different concentrations of PhMA and DME. The pressure−temperature slope for P(PhMA) + CO2 + PhMA system switched from UCST-type with negative slope to LCST-type with positive slope according to the increase of the concentration of PhMA monomer (i.e., 39.4, 45.8, 54.2, 59.9, and 62.1 wt %). When PhMA of 62.1 wt % is added to the P(PhMA) + CO2 solution, the p−T curve shows the typical LCST-type. The effect of DME on the P(PhMA) + DME (from 79.0 to 95.8 wt %) solution in SCF CO2 is investigated to maximum temperatures and pressure of 453.9 K and 147 MPa, respectively. In addition, high-pressure experimental data of p−x isotherm for CO2 + PhMA binary system were acquired at the temperatures range from 313.2 to 393.2 K and to a maximum pressure of 24.90 MPa. The measured experimental data were regressed by PR EoS with two adjustable binary interaction parameters, and the calculated results show a good agreement with experimental data with accuracy of 3.44% RMSD error. The critical pressure locus curves between the experimental and predicted values show likewise reasonable agreement.

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AUTHOR INFORMATION

Corresponding Author

*Tel.: +82-61-659-7296. Fax: +82-61-653-3659. E-mail address: [email protected] (H.S.B.). ORCID

Hun-Soo Byun: 0000-0003-2356-8515 Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (Grant NRF2016R1D1A1B04931921).

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REFERENCES

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Phase Behavior for the Poly(phenyl methacrylate) and Phenyl

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