2016 TUM Magnetic Sensor

Thermo-responsive Polymeric Magnetic Sensor

▶ Copolymer Templated Magnetic Sensor

Dissertation: H Xu, et al. Structure and Properties of Thermoresponsive Diblock Copolymers Embedded with Metal Oxide Nanoparticles [D]. TU & LMU München. 2016 [Link] [Poster]

• Polymer Basics

Copolymers

Structure of Copolymers

Thermoresponsive Effect

• Fundamentals of Magnetism

Susceptibility

Figure 2-8: Classification of materials on the basis of susceptibility [30]

Type of Magnetic Field

• Materials Preparation

Preparation

Figure 3-4: Schematic diagram of solution casting method where bulk samples are sandwiched between two mica windows.

Figure 3-5: Schematic diagram of spin-coating method.

• Diblock Structure Characterization

Characterization

Figure 5-1: (a) SAXS profile of iron salt/ PS-b-PNIPAM nanocomposites with [Fe]/[NIPAM] molecular ratio increasing from 0 to 0.5. (b) Lamellar distance D versus [Fe]/[NIPAM] molecular ratio extracting from the fitting results of SAXS profiles in (a) by Scatter software.

Figure 5-2: SAXS 2D profiles of iron salt / PS-b-PNIPAM DBC nanocomposites with [Fe]/[NIPAM] molecular ratio of 0, 0.01, 0.03, 0.05 and 0.1 corresponding to figure a) to e).

Figure 5-6: SEM images of both bare a) PS-b-PNIPAM and b) PS-b-PNIPAM DBCs

• Thermoresponsive Behaviour

Thermoresponsive

Figure 5-8: Peak fitting results of 1D SAXS profiles for q position and FWHM and its evolution versus time during three temperature cycles.

Figure 5-9: Schematic of block structure evolution versus time for PS-b-PNIPAM in high relative humidity.

Figure 5-13: a) SAXS 1D profiles of PS-b-PNIPAM DBC bulk sample in water vapor and water:THF=1:1 mixed vapor for 1~2 weeks. b) Peak fitting results of the 1D SAXS profiles in figure a).

• Magnetic Properties

Magnetism

Figure 5-16: Magnetic moments measured as a function of external magnetic fields at 2K, 150K and 300K for PS-b-PNIPAM DBC / Fe salt or Fe NPs nanocomposites

Figure 5-17: Coercivity Bc extracted from the measured magnetic moments at different temperatures 2K, 150K and 300K for PS-b-PNIPAM DBC / Fe salt or Fe NPs nanocomposites