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![Fluorescence Spectroscopy
FL Spectrophotometer
Samples with pyrene
find 𝐼1/𝐼3 ratio
CMC from 𝐼1/𝐼3 VS. log(concentration) plot
UV-Vis Spectroscopy
UV-Vis Spectrophotometer
Samples with DPH
Absorbance value at 356 nm
METHODS
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
Intensity
460440420400380360340
Wavelength [nm]
Alexandridis, P., J.F. Holzwarth, and T.A. Hatton, MICELLIZATION OF POLY(ETHYLENE OXIDE)-POLY(PROPYLENE OXIDE)-POLY(ETHYLENE OXIDE) TRIBLOCK COPOLYMERS IN AQUEOUS-SOLUTIONS -
THERMODYNAMICS OF COPOLYMER ASSOCIATION. Macromolecules, 1994. 27(9): p. 2414-2425.
Winnik, Mitchell A.. "Fluorescence Probe Studies of Pluronic Copolymer Solutions as a Function of Temperature." Langmuir: 730-737. Print
Aguiar, J., et al., On the determination of the critical micelle concentration by the pyrene 1 : 3 ratio method. Journal of Colloid and Interface Science, 2003. 258(1): p. 116-122.](https://image.slidesharecdn.com/e59b5e30-21e6-42ba-89fc-bf98f6d60216-161002024029/75/Micellization-of-Alcohol-Ethoxylate-Surfactants-6-2048.jpg)
![RESULTS-FLUORESCENCE DATA
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
I1/I3
0.001 0.01 0.1 1 10
Lutensol Concentration [wt%]
XP-90
XL-90
XL-140
ES 8928-B
Lutensol® CMC (Wt %)
XP-90 0.2
XL-90 0.1
XL-140 0.25
ES 8928-B 0.9](https://image.slidesharecdn.com/e59b5e30-21e6-42ba-89fc-bf98f6d60216-161002024029/75/Micellization-of-Alcohol-Ethoxylate-Surfactants-8-2048.jpg)
![RESULTS-FLUORESCENCE DATA
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
I1/I3
0.001 0.01 0.1 1 10
Lutensol Concentration [wt%]
XP-90
XL-90
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
I1/I3
0.001 0.01 0.1 1 10
Lutensol Concentration [wt%]
XP-90
ES 8928-B](https://image.slidesharecdn.com/e59b5e30-21e6-42ba-89fc-bf98f6d60216-161002024029/75/Micellization-of-Alcohol-Ethoxylate-Surfactants-9-2048.jpg)
![RESULTS-UV DATA
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
Absorbance(A.U.)
0.001 0.01 0.1 1 10
Lutensol Concentration [wt%]
XP-90
XL-90
XL-140
ES 8928-B](https://image.slidesharecdn.com/e59b5e30-21e6-42ba-89fc-bf98f6d60216-161002024029/75/Micellization-of-Alcohol-Ethoxylate-Surfactants-11-2048.jpg)
More Related Content
Micellization of Alcohol Ethoxylate Surfactants
- 1. Jenny Chen Dr. Alexandridis Group MICELLIZATIONOF ALCOHOL ETHOXYLATE SURFACTANTS
- 2. Application of surfactants Formationof micelles in water Surfactants Hydrophilic Hydrophobic parts “Hydrophobic Effect” Driving force : Entropy MICELLIZATION OF SURFACTANTS Sarkar, B. and P. Alexandridis, Alkyl Propoxy Ethoxylate "Graded" Surfactants: Micelle Formation and Structure in Aqueous Solutions. Journal of Physical Chemistry B, 2010. 114(13): p. 4485-4494.
- 3. Polar head groupsize Larger head groups increases critical micellization concentration (CMC) More hydrophilic Alkyl Chain Length (hydrophobic) Longer chain decreases CMC More hydrophobic GENERAL TRENDS "Micellar solubilization of drugs.." Micellar solubilization of drugs.. N.p., n.d. Web. 7 May 2014. <http://www.ualberta.ca/~csps/JPPS8(2)/C.Rangel-Yagui/solubilization.htm>. Evans, D. Fennell, and Ha m. The colloidal domain: where physics, chemistry, biology, and technology meet. 2nd ed. New York: Wiley-VCH, 1999. Print.
- 4. Hydrophilic poly(ethyleneoxide) (PEO) head group Hydrophobic alkyl chain (tail) Poly(propylene oxide) (PPO) segment “Graded hydrophobicity” PPO is hydrophobic in water How character change based on: Molecular architecture, solvent ALKYL PROPOXY ETHOXYLATE (APE) PEO head group- PPO -Alkyl chain Sarkar, B. and P. Alexandridis, Alkyl Propoxy Ethoxylate "Graded" Surfactants: Micelle Formation and Structure in Aqueous Solutions. Journal of Physical Chemistry B, 2010. 114(13): p. 4485-4494.
- 5. Lutensol® : Branchedfatty alcohol alcoxylate Pyrene DPH MATERIALS Surfactant Structure XP-90 9 EO XL-90 9 EO and a PO XL-140 14 EO and a PO ES 8928-B 20 EO n O O n O "Lutensol®." - Non-ionic surfactants. N.p., n.d. Web. 7 May 2014. <http://www.basf.com/group/corporate/us/en/brand/LUTENSOL>.
- 6. Fluorescence Spectroscopy FL Spectrophotometer Sampleswith pyrene find 𝐼1/𝐼3 ratio CMC from 𝐼1/𝐼3 VS. log(concentration) plot UV-Vis Spectroscopy UV-Vis Spectrophotometer Samples with DPH Absorbance value at 356 nm METHODS 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 Intensity 460440420400380360340 Wavelength [nm] Alexandridis, P., J.F. Holzwarth, and T.A. Hatton, MICELLIZATION OF POLY(ETHYLENE OXIDE)-POLY(PROPYLENE OXIDE)-POLY(ETHYLENE OXIDE) TRIBLOCK COPOLYMERS IN AQUEOUS-SOLUTIONS - THERMODYNAMICS OF COPOLYMER ASSOCIATION. Macromolecules, 1994. 27(9): p. 2414-2425. Winnik, Mitchell A.. "Fluorescence Probe Studies of Pluronic Copolymer Solutions as a Function of Temperature." Langmuir: 730-737. Print Aguiar, J., et al., On the determination of the critical micelle concentration by the pyrene 1 : 3 ratio method. Journal of Colloid and Interface Science, 2003. 258(1): p. 116-122.
- 7. CMC FROM 𝐼1/𝐼3VS. LOG(CONCENTRATION) PLOT
- 8. RESULTS-FLUORESCENCE DATA 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 I1/I3 0.001 0.010.1 1 10 Lutensol Concentration [wt%] XP-90 XL-90 XL-140 ES 8928-B Lutensol® CMC (Wt %) XP-90 0.2 XL-90 0.1 XL-140 0.25 ES 8928-B 0.9
- 9. RESULTS-FLUORESCENCE DATA 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 I1/I3 0.001 0.010.1 1 10 Lutensol Concentration [wt%] XP-90 XL-90 1.8 1.7 1.6 1.5 1.4 1.3 1.2 1.1 I1/I3 0.001 0.01 0.1 1 10 Lutensol Concentration [wt%] XP-90 ES 8928-B
- 10. RESULTS-UV DATA 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.001 0.010.1 1 10 Absorbanceat356nm Log(concentration) XP-90 0.06
- 11. RESULTS-UV DATA 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0.00 Absorbance(A.U.) 0.001 0.010.1 1 10 Lutensol Concentration [wt%] XP-90 XL-90 XL-140 ES 8928-B
- 12. 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 XP-90 XL-90 XL-140ES 8928-B CMC Surfactant FL UV RESULTS- FLUORESCENCE VS. UV DATA Lutensol® CMC (FL) (Wt %) CMC (UV) (Wt %) XP-90 0.2 0.06 XL-90 0.1 0.08 XL-140 0.25 0.1 ES 8928-B 0.9 0.6
- 13. Lutensol® CMC (Wt %) CMC (mol frac) ΔG (KJ/mol) XP-900.2 6.56E-05 -23.9 XL-90 0.1 3.13E-05 -25.7 XL-140 0.25 5.67E-05 -24.2 ES 8928-B 0.9 1.63E-04 -21.6 RESULTS- FREE ENERGY OF MICELLIZATION ΔG=RTln(𝑋 𝑪𝑴𝑪)
- 14. Lutensol® ΔG mic (KJ/mol) ΔG(C)mic (KJ/mol) ΔG(EO)mic (KJ/mol) ΔG micPO (KJ/mol) XP-90 -23.9 -36.6 - - XL-90 -25.7 -36.6 8.9 2 XL-140 -24.2 -36.6 9.4 3 ES 8928-B -21.6 -36.6 - - RESULTS- FREE ENERGY CONTRIBUTION ΔG=RTln(𝑋 𝑪𝑴𝑪) ΔG=ΔG(C)+ΔG(PO)+ΔG(EO)ΔG (C)=−3.0(𝐍 𝐂 − 𝟏) − 𝟗. 𝟔
- 15. Different molecularstructure = Graded PO character Different ΔG of micellization Hydrophobic Hydrophilic groups Innovation CONCLUSION "The Thomas Group - PTCL, Oxford." The Thomas Group - PTCL, Oxford. N.p., n.d. Web. 7 May 2014. http://rkt.chem.ox.ac.uk/topics/surfactant.html
- 16. Dr. Alexandridis Andrew Bodratti Gulfof Mexico Research Initiative (GoMRI) BASF Care Products (Dr. Elvira Stesikova) ACKNOWLEDGEMENTS
- 17. 1. Sarkar, B.and P. Alexandridis, Alkyl Propoxy Ethoxylate "Graded" Surfactants: Micelle Formation and Structure in Aqueous Solutions. Journal of Physical Chemistry B, 2010. 114(13): p. 4485-4494. 2. Alexandridis, P., J.F. Holzwarth, and T.A. Hatton, MICELLIZATION OF POLY(ETHYLENE OXIDE)- POLY(PROPYLENE OXIDE)-POLY(ETHYLENE OXIDE) TRIBLOCK COPOLYMERS IN AQUEOUS-SOLUTIONS - THERMODYNAMICS OF COPOLYMER ASSOCIATION. Macromolecules, 1994. 27(9): p. 2414-2425. 3. Aguiar, J., et al., On the determination of the critical micelle concentration by the pyrene 1 : 3 ratio method. Journal of Colloid and Interface Science, 2003. 258(1): p. 116-122. 4. "Lutensol®." - Non-ionic surfactants. N.p., n.d. Web. 7 May 2014. <http://www.basf.com/group/corporate/us/en/brand/LUTENSOL>. 5. "Micellar solubilization of drugs.." Micellar solubilization of drugs.. N.p., n.d. Web. 7 May 2014. <http://www.ualberta.ca/~csps/JPPS8(2)/C.Rangel-Yagui/solubilization.htm>. 6. "The Thomas Group - PTCL, Oxford." The Thomas Group - PTCL, Oxford. N.p., n.d. Web. 7 May 2014. http://rkt.chem.ox.ac.uk/topics/surfactant.html 7. Winnik, Mitchell A.. "Fluorescence Probe Studies of Pluronic Copolymer Solutions as a Function of Temperature." Langmuir: 730-737. Print. 8. Evans, D. Fennell, and Ha m. The colloidal domain: where physics, chemistry, biology, and technology meet. 2nd ed. New York: Wiley -VCH, 1999. Print. REFERENCES
Editor's Notes
- #3 Understanding how surfactants act and react is important because they are applied in many areas. For example, they are used in personal care products, lubrication, detergency, and paint formulation. Surfactants are amphiphilic compounds, meaning they have a hydrophobic and a hydrophilic part. The formation of micelles of surfactants in water occurs due to the “hydrophobic effect”, meaning the hydrophobic tail of the surfactant aggregate while the head group forms a kind of barrier for the tail from touching water. Thus, forming a micelle structure. The driving force of Micellization in water is entropy. Before Micellization, entropy of the system is low because of the unfavorable interaction between the hydrophobic tail and water, which leads to micelles forming in order to increase entropy.
- #4 Larger hydrophilic head groups increases CMC, which is the concentration of surfactants where micelles start to form. And a larger hydrophobic tail will decreases CMC.
- #5 APE are non-ionic surfactants with hydrophilic PEO head group, hydrophobic alkyl chain, and PPO segment. PPO is hydrophobic in water, but when in this surfactant, it has a “graded character”, so the level of hydrophobicity in APE changes We want to know how this character changes through molecular architecture and different solvent conditions.
- #6 We experimented with a surfactant called lutensol, which is branched fatty alcohol alcoxylate. The XP and ES types do not have PPO segment, while the XL types do. The number, 90, in the name, means there are 9 PEO groups, while 140 means there are 14 PEO groups and ES 8928-B has 20 PEO groups. We also used pyrene and DPH to help indicate when micelles form.
- #7 Using fluorescence spectroscopy , we made samples of varied concentrations of surfactants and added pyrene to them. This will give us 5 peaks. The ratio of peak 1 to peak 3 will will indicate when micelles are formed. After collecting the data, we plotted 𝐼 1 / 𝐼 3 vs. log(concentration) plot to find the CMC value. A second method was used with UV-Vis Spectrophotometer to find the absorption spectra of samples containing DPH. DPH will solubilize when micelles form. We found CMC by plotting absorption at main peak at 356 nm vs. log(concentration)
- #8 As mentioned before. We look at the second inflection point from the i1:i3 plot to find CMC.
- #9 These plots shows i1/i3 for all four surfactants. From the plots, we found the CMC values. You could clearly see and compare the cmc values from these plots.
- #10 Comparing XP90 to XL90. The only difference between the two is that XL90 has a PO group, which seemed to have made a difference in CMC. If you look at the graph, you see that XP90 has higher CMC than XL90, meaning micelles form at a higher concentration for XP90. So it seems that the hydrophobic nature of the PO segment might have caused micelles to form at a lower concentration. If you look at the next graph, the cmc for ES8928B is at a greater concentration, so it is more hydrophilic than XP90. Also, the intensity ratio is greater for ES8928B than it is for XP90, which also indicates it is more hydrophilic than XP90.
- #11 This is the UV plotted data of absorption at 356 nm vs. log(concentration). We look for the first inflection point to find CMC. We can see that at that point, DPH starts to solubilize because of the hydrophobic environment when micelles form.
- #12 This graph shows the absorbance plots for all four surfactants
- #13 Comparing the 2 methods, the UV method seem to yield a lower CMC value.
- #14 Using the CMC values, free energy of micellization could be calculated for each surfactant. ΔG is negative, which is to be expected because the formation of micelles were spontaneous. From the data, we can see that the greater the CMC, the less negative ΔG is. This expected because surfactants will be less prone to forming micelle as it becomes more hydrophilic.
- #15 Looking at how the molecular structure of each surfactant might affect the free energy of micellization, we see that ΔG contribution from alkyl chain is very negative. This is because the alkyl chain is strongly hydrophobic. The EO head group contributes a positive ΔG, which is expected because it is hydrophilic. Comparing XL-90 to XL-140, XL-140 head group contributes a more positive ΔG because it has more EOs. (Δ G of the PO group was determine by subtracting ΔG of alkyl chain and EO group from ΔG of micellization.) We can observe that the PO group contributes a low positive ΔG. Meaning it is acting weakly hydrophilic, which was not expected based on the CMC comparison from the FL and UV readings, where it was concluded that the PO group’s hydrophobicity was the reason for the low CMCs in XL90 and XL140.
- #16 By understanding how different molecular structure affect the degree of hydrophobicity of a surfactant, we can control how easily they from micelles. Thus, discovering how parts of surfactants contribute to the way they react is important when trying to innovate products and methods.