KWS-2

• Colloids, nanocomposites, polymer gels, networks
• Polymer blends, diblock copolymers
• Microemulsions, complex fluids, micelles
• Membranes, films; in-situ adsorption – desorption/humidifying – drying phenomena
• Kinetics of demixing, formation, aggregation
• Shear induced micelle deformation, rubber network deformation, nanocomposite ordering
• Protein structure and folding/ unfolding
• Pressure dependence of phase diagrams, fluctuations, molecular interactions
• In-situ crystallisation semi-crystalline polymer

Self-assembly of block-copolymers in micellar structures is a widely studied topic at KWS-2. The properties of block-copolymer micelles tuned by changing e.g. solvent quality, temperature, solvent selectivity, block copolymer composition, and molecular weight are investigated thoroughly benefiting from the adjustable instrumental resolution between 2 and 20%.

Another kind of typical application relate to fast structural changes of micellar systems (formation, transformation or chain exchange at equilibrium) or polymer crystallisation which are investigated by time-resolved SANS in the second or sub-second (up to 50 ms) regimes. More recently, the determination and control of the morphological parameters of biocompatible gels and amphiphiles became an important topic of study stimulated by the demands from nanomedicine related to the design of new functional drug delivery vehicles.

• Anton-Paar fluid rheometer
• Stopped flow cell
• Sample holders: 9 horizontal x 3 vertical (temperature controlled) for standard Hellma cells
• Oil & water thermostats (typical 10 …100°C)
• 8-positions thermostated (Peltier) sample holder (-40°C … 150°C)
• Magnet (1.5 T, vertical)
• Cryostat with sapphire windows
• Pressure cells (500 bar, 5000 bar)
• Humidity chamber, 5% … 95% for 10°C … 60°C

Complementary in-situ techniques (optional at sample aperture, see instrument drawing)

• FT-IR spectroscopy
• DLS & SLS
• ³He spin analyzer (SEOP)

Overall performance

• Q = 0.0001… 1 Å^-1
• Maximal flux: 2 x 10⁸ n cm^-2 s^-1
• Typical flux: 2.5 x 10⁷ n cm^-2 s^-1 (collimation 8 m, 50 x 50 mm², λ = 5 Å)

Velocity selector

• Astrium, Δλ/λ = 10% standard) or 20% tilted selector), λ = 3… 20 Å

Chopper

• Tunable Δλ/λ: 20%… 2% (TOF analysis)

Active apertures

• 2 m, 4 m, 8 m, 14 m, 20 m, sample position

Aperture sizes

• Rectangular 1 x 1 mm² – 50 x 50 mm²

Neutron lenses

• MgF₂, diameter 50 mm, curvature 20 mm
• Packs with 4, 6,16 lenses

Polariser

• Transmission, P > 95% for λ > 4.5Å

Sample stage

• XYZθ translational-rotational stage + craddle
• Accuracy better than 0.01°, 0.01 mm

Detector 1

• Detection range: continuous 1 – 20 m
• ³He tubes array
• active area ~0.9 m²
• count rate for no deadtime >2 MHz
• resolution = < 8 mm
• stability of pixel response ~0.1%
• efficiency 85% for 5 Å

Detector 2 (high res.)

• Spatial resolution 0.45 x 0.45 mm²
• Active area: Ø = 8.7 cm
• ⁶Li-Scintillator 1 mm thickness
• Fixed position: 17 m after sample position