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LUND UNIVERSITY LIBRARIES

A Light Scattering and Calorimetry Study on the Interaction between PEO-PPO-PEO Triblock Copolymers and the Bile Salt Sodium Glycodeoxycholate

Anderberg Haglund, Caroline LU (2014) KEMN10 20141
Department of Chemistry
Abstract
The interaction between two block copolymers (Pluronic® P65 and F127) and the bile salt sodium glycodeoxycholate (NaGDC) was investigated by means of static and dynamic light scattering (SLS and DLS) and differential scanning calorimetry (DSC). First a temperature study on pure P65 (1.0 wt%) in water in the temperature interval 5-80 °C revealed a critical micellization temperature of about 40 °C from SLS and 38 °C from DSC. The approximate hydrodynamic radius of unimers and micelles determined by DLS were 0.8±0.5 nm (at 45 °C) and 6.43±0.09 nm (at 50 °C), respectively. The interactions of P65 and F127 (1.0 and 5.0 wt%) with NaGDC at MR 0, 0.3, 0.6, and 2.9 (MR=n_NaGDC⁄n_polymer ) was thereafter investigated. For both block copolymers,... (More)
The interaction between two block copolymers (Pluronic® P65 and F127) and the bile salt sodium glycodeoxycholate (NaGDC) was investigated by means of static and dynamic light scattering (SLS and DLS) and differential scanning calorimetry (DSC). First a temperature study on pure P65 (1.0 wt%) in water in the temperature interval 5-80 °C revealed a critical micellization temperature of about 40 °C from SLS and 38 °C from DSC. The approximate hydrodynamic radius of unimers and micelles determined by DLS were 0.8±0.5 nm (at 45 °C) and 6.43±0.09 nm (at 50 °C), respectively. The interactions of P65 and F127 (1.0 and 5.0 wt%) with NaGDC at MR 0, 0.3, 0.6, and 2.9 (MR=n_NaGDC⁄n_polymer ) was thereafter investigated. For both block copolymers, small additions of NaGDC were observed to enhance the micellization of the polymers, shifting the onset temperature towards lower temperatures with increasing MR. In the case of the P65/NaGDC system larger additions have the opposite effect, however this was not observed for the F127/NaGDC system. DLS experiments on block copolymer/NaGDC mixed systems indicate the presence of repulsive electrostatic interactions between the block copolymer micelle/NaGDC mixed complexes that are formed at lower molar ratios. For the P65 system at the highest molar ratio the DLS data showed a bimodal relaxation time distribution, which is interpreted as the diffusion of two species; small NaGDC-rich and P65 micelle/NaGDC complexes. The effect of NaGDC is not as evident on F127, explained by the difference in hydrophilicity between the polymers. For both mixed systems a decreased relaxation time and Rayleigh ratio is observed with increased MR, indicating that the value of the second virial coefficient grows larger with increased MR and which also confirms the observed increase in the electrostatic repulsion among the complexes upon increasing the NaGDC content. From these results it was concluded that NaGDC interacts with block copolymers P65 and F127 in a similar fashion to the previously studied ionic surfactants sodium dodecyl sulfate and hexadecyltrimethylammonium chloride, with an enhanced micellization at low surfactant additions and a breakup of the micelles at higher additions. (Less)
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author
Anderberg Haglund, Caroline LU
supervisor
organization
course
KEMN10 20141
year
type
H2 - Master's Degree (Two Years)
subject
keywords
bile salt, NaGDC, sodium glycodeoxycholate, triblock copolymer, Pluronic P65, Pluronic F127, PEO-PPO-PEO
language
English
id
4497639
date added to LUP
2014-07-01 16:29:42
date last changed
2014-07-01 16:29:42
@misc{4497639,
  abstract     = {{The interaction between two block copolymers (Pluronic® P65 and F127) and the bile salt sodium glycodeoxycholate (NaGDC) was investigated by means of static and dynamic light scattering (SLS and DLS) and differential scanning calorimetry (DSC). First a temperature study on pure P65 (1.0 wt%) in water in the temperature interval 5-80 °C revealed a critical micellization temperature of about 40 °C from SLS and 38 °C from DSC. The approximate hydrodynamic radius of unimers and micelles determined by DLS were 0.8±0.5 nm (at 45 °C) and 6.43±0.09 nm (at 50 °C), respectively. The interactions of P65 and F127 (1.0 and 5.0 wt%) with NaGDC at MR 0, 0.3, 0.6, and 2.9 (MR=n_NaGDC⁄n_polymer ) was thereafter investigated. For both block copolymers, small additions of NaGDC were observed to enhance the micellization of the polymers, shifting the onset temperature towards lower temperatures with increasing MR. In the case of the P65/NaGDC system larger additions have the opposite effect, however this was not observed for the F127/NaGDC system. DLS experiments on block copolymer/NaGDC mixed systems indicate the presence of repulsive electrostatic interactions between the block copolymer micelle/NaGDC mixed complexes that are formed at lower molar ratios. For the P65 system at the highest molar ratio the DLS data showed a bimodal relaxation time distribution, which is interpreted as the diffusion of two species; small NaGDC-rich and P65 micelle/NaGDC complexes. The effect of NaGDC is not as evident on F127, explained by the difference in hydrophilicity between the polymers. For both mixed systems a decreased relaxation time and Rayleigh ratio is observed with increased MR, indicating that the value of the second virial coefficient grows larger with increased MR and which also confirms the observed increase in the electrostatic repulsion among the complexes upon increasing the NaGDC content. From these results it was concluded that NaGDC interacts with block copolymers P65 and F127 in a similar fashion to the previously studied ionic surfactants sodium dodecyl sulfate and hexadecyltrimethylammonium chloride, with an enhanced micellization at low surfactant additions and a breakup of the micelles at higher additions.}},
  author       = {{Anderberg Haglund, Caroline}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{A Light Scattering and Calorimetry Study on the Interaction between PEO-PPO-PEO Triblock Copolymers and the Bile Salt Sodium Glycodeoxycholate}},
  year         = {{2014}},
}