טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentGoldgraber Ilanit
SubjectCharacterization of Thermo Responsive Polymer Systems
in Aqueous Solutions
DepartmentDepartment of Chemical Engineering
Supervisor Professor Havazelet Bianco-Peled


Abstract

This research focuses on a new material that was developed by Prof. Daniel Cohen from the Hebrew Universit y in Jerusalem. This material, termed DP4, is made of four F127 molecules attached to each other head-to-tail, leading to a molecule with four basic unit.

The main aims of the research were to understand the self-assembly of the DP4 compared to F127 by evaluating the critical micelle concentration (CMC) and critical temperature for micellization (CMT), to characterize the aggregation properties of the DP4 due to concentration and temperature changes and to understand the gel behavior of the DP4 in different temperatures and concentrations.

Light scattering was used is order to measure the CMC and CMT. The CMC curves of the DP4 is resemble that of the F127, The CMT values for the DP4 were also lower then these of the F127.

In order to characterize the aggregation properties of the DP4 and to study the mechanism of gel formation in DP4 we have used Small Angle Neutron Scattering (SANS) measurements. Two theoretical models fit the experimental SANS results. The cap-and-gown model describes a spherical core shell structure and In addition the intermicellar factor, which describes the interaction between the micelles, is calculated. The Mortensen model divides the micelle formation to 3 main stages. At low temperature as independent polymer chains called unimers. It becomes more hydrophobic upon increasing the temperature and spherical micelles are formed. The scattering function becomes increasingly dominated by the correlation hole upon increasing polymer concentration or temperature, revealing significant inter-micellar correlations.