Particle Size Determination with Dynamic Light Scattering DLS

Transcription

1 Particle Size Determination with Dynamic Light Scattering DLS Applications with the Nano Particle Sizer ANALYSETTE 12 DynaSizer The new ANALYSETTE 12 DynaSizer uses the dynamic light scattering as a measuring method and therefore enables the measurement of particle size distributions between 1 and 6000 nm. The advantages of this measuring method are described by means of three different samples (black ink, gold nano particles and Nano capsules with hydrous core).

2 Content: Analysis of black ink Analysis of gold nano particles Analysis of Nano capsules with hydrous core (NLCA) The ANALYSETTE 12 DynaSizer Features overview

3 Analysis of black ink with the Nano Particle Sizer ANALYSETTE 12 DynaSizer Setting of the task Analysis of both batches of black ink, labelled A and B with the Nano Particle Sizer ANALYSETTE 12 DynaSizer. It is UV drying black liquid paint, consisting of organic dispersion pigments and acrylic. The size of the pigments contained in the sample and possible additives shall be measured. A diluting agent supplied by the manufacturer enables the dilution of the paints. But we also want to analyse and evaluate the paints without dilution and without any alterations. Analysis of the diluted paints The paints which we will characterize are deep black and opaque so it is impossible to measure them with dynamic light scattering in classic configurations. This would especially bear the risk, to locally heat up the sample with the laser beam, which would falsify the measurement. A first solution is to dilute the sample in such a manner, that half transparent samples evolve. The samples in batches A and B must be heavily diluted with a diluting agent in order to generate an acceptable transparency. In this case we used a time dilution prior to measuring the Nano Particle Sizer ANALYSETTE 12 DynaSizer. According to the manufacturer, the viscosity of the acrylic is 35cps and the refraction index is Despite the heavy dilution, the ANALYSETTE 12 DynaSizer recognizes a suitable and within one to two minutes after the start of the measurement an analyzable signal. This signal relates to particles in the submicron range of both samples. In order to obtain a statistic evaluation of the particle size, we program more successive measurements of 120 seconds and collect the results. The results of these analyses were documented in a histogram of the cumulated sizes in figure 1 for the diluted batch B and in figure 2 for the diluted batch A.

4 Figure 1: Batch B, times diluted: The histogram shows the cumulated size which we obtained by several measurements in 120 seconds. The height of the bar corresponds with the share of the evaluated particles in regards to the entire intensity of the signal. Figure 2: Batch A, times diluted: The histogram shows the cumulated size which we obtained by several measurements in 120 seconds. The height of the bar corresponds with the share of the evaluated particles in regards to the entire intensity of the signal. Initially the results show that the times diluted paint B, basically consists of relatively monodispers particles and around on average hydrodynamic diameter of 32 nm, centred particles. During the analysis though, in certain areas, several larger particles were also discovered (up to 1.3 Microns). Batch A, the of 10,000 times diluted paint, basically consists of an average hydrodynamic diameter of 48 nm centred particles.

5 The distribution of this sample seems a little larger than the previous sample, with a particle distribution between 22 and 100 nm. During the analysis though, in certain areas, several larger particles were also discovered (up to1.2 Microns). Analysis of the undiluted paints In order to analyse the unaltered paint especially without heavy dilution the Nano Particle Sizer ANALYSETTE 12 DynaSizer offers the possibility, to operate in a Thin-Layer mode. This with the excess energy collector of the laser beam (photon trap) connected type of configuration, facilitates the avoidance of the heating-up effect of opaque and absorbent samples. Both paints are therefore directly tested with a Thin-Layer with strength in the range of 20 micrometer. The instrument recognizes an interpretable signal within three minutes after the measurement. In order to obtain a statistic evaluation of the size of these particles like before, we program several successive measurements of 180 seconds and collect the results. We documented the results of these analyses in a histogram of the cumulative values in figure 3 for the undiluted batch B and in figure 4 for the undiluted batch A. Figure 3: Batch B undiluted: The histogram shows the cumulated value obtained via several measurements of 180 seconds. The height of the bar relates to the share of the evaluated particles in relation to the intensity of the signal.

6 Figure 4: Batch A undiluted: The histogram shows the cumulated value obtained via several measurements of 180 seconds. The height of the bar relates to the share of the evaluated particles in relation to the intensity of the signal. The result The results of the analysis of the undiluted paints greatly differ from he results of the analysis with heavy dilution. The average size in the undiluted sample B existing particles is approximately 40 nm, but seems much more polydispers as with the diluted sample. We especially observe statistically clearly more particles between 30 and 100 nm. This result is even more significant with paint A. The discovered particles have an even stronger in the direction of the larger sizes shifted distribution, meaning between approximately 10 nm and nm with an average hydrodynamic diameter of 72 nm. We were able to analyse both paints in diluted and undiluted condition. Both samples showed larger particle amounts in the range of several dozen nanometres; on average nm with batch B and approximately nm with batch A. It seems though that the concentration influences the existing larger particles in the sample in a size range of one or several dozen nanometres. A possible explanation for this could be for example, the existence of additives made up of fine particles, which are vaguely bonded with the pure paint. These could be redispersed after a dilution of the system.

7 Analysis of gold nano particles with the Nano Particle Sizer ANALYSETTE 12 DynaSizer Task Characterization of one sample of gold nano particles, through dynamic light scattering with the Nano Particle Sizer ANALYSETTE 12 DynaSizer. Details about the sample and the measurement The sample is directly measured pure without any dilution by using the ultra-thin layer function of the Nano Particle Sizer ANALYSETTE 12 DynaSizer. Physical properties of the sample Temperature: 25 C Viscosity: Refraction Index (solvent): 1.3 Amplitude vs diameter Figure 1: Cumulative size histogram obtained with 1 minute measurement. The height of a column represents the share of the considered particles to the total intensity of the signal. The sample appears to be polydisperse, with hydrodynamic diameters measured from about 110 nm to 6 μm. The population of big amplitude centred on an average diameter of 250 nm is probably in majority.

8 Number of particles (%) vs diameter Figure 2: Cumulative size histogram after the Mie correction. The height of a column represents the ratio of objects in term of number of particles. The size distribution report by number of particles indicates that the sample is centred on an average diameter of 120 nm.

9 Analysis of Nano capsules with hydrous core (NLCA) with the Nano Particle Sizer ANALYSETTE 12 DynaSizer Task Analysis of a dispersion of nano capsules with hydrous core in water, through dynamic light scattering with the Nano Particle Sizer ANALYSETTE 12 DynaSizer. Sample preparation The provided sample was already 100 times diluted. This 1/100 diluted NLCA sample was measured and then the sample was again diluted 100 times with distilled water and afterwards analysed - altogether a dilution of a factor 1/ was conducted. Physical properties of the sample - Temperature: 20 C - Dynamic Viscosity of the solvent: 100cps - Refraction index of the solvent: Analysis of the 1/100 times diluted NLCA The Die ANALYSETTE 12 DynaSizer already recognizes within three minutes after the start of the measurement a suitable and analysable signal. In order to obtain a statistic assessment of the size of these particles, we program several successive measurements of 180 seconds and gather the results. The result of this analysis was documented in a histogram of the cumulated size in figure 1 (presentation of the result in the amplitude of the scattered light). Figure 1: Sample NLCA diluted 1/100 times. The histogram shows the cumulative size obtained after several measurements within 3 minutes. The height of a bar corresponds with the share of the evaluated particles in regards to the entire intensity of the signal.

10 The sample contains particles with a hydrodynamic diameter between 80 nm and 470 nm. The maximum measured amplitude equates to a hydrodynamic diameter of 165 nm. Analysis of the 1/ diluted NLCA The ANALYSETTE 12 DynaSizer recognizes within five minutes after the start of the measurement a suitable and analysable signal. The result of this analysis was documented in a histogram of the cumulated size in figure 2 (presentation of the result in the amplitude of the scattered light). Figure 2: Sample NLCA diluted 1/ The histogram shows the cumulated size obtained after several measurements within 5 minutes. The height of the bar corresponds with the share of the evaluated particles in regards to the entire intensity of the signal. The maximum measured amplitude equates to a hydrodynamic diameter of 165 nm.

11 Features overview - ANALYSETTE 12 DynaSizer Smallest sample volumes For measurements with the ANALYSETTE 12 DynaSizer only smallest sample volumes of 50 μl 5 ml are necessary, which are applied directly onto the optical measuring cell inside the instrument: making disposables such as cuvettes or similar obsolete. Due to the intelligent design, cleaning is as easy as a child s play. Measurement of ultra thin layers Due to the cuvette-free design the thickness of the measurement layer can be variably adjusted. This enables measurements of even extremely thin layers and prevents unwanted multi-scattering effects. It also facilitates the measurement of highly concentrated suspensions as well as in dark media. ANALYSETTE 12 DynaSizer measurement system Variable laser power The power of the laser of the ANALYSETTE 12 DynaSizer is variably adjustable and allows measurements of very dark samples or high particle concentrations of up to 40 Vol.-%. Particle size distribution and particle concentration The maximum output power of 65 mw at a wavelength of 658 nm allows the measurement of low particle concentrations. In addition to analysis according to the cumulant method, the powerful Padé-Laplace algorithm is also available for multimodal samples. Combined with the multiacquisition mode, it is possible to determine medium particle sizes, complete particle size distributions and the polydispersity-index. Effective, user-friendly and accurate to the nanometer! The advantage of the ANALYSETTE 12 DynaSizer at a glance: Particle size measurement via dynamic light scattering at a constant scattering angle of 135 Measuring range form 1 nm to 16 µm, smallest sample quantities 50 μl 5 ml Simple sample feeding directly into the instrument Ultra-Thin Layer an extremely thin measurement layer avoids multiple scatterings Measurement of particle concentrations between % up to 40 Vol.-% Limitation of laser-induced-temperature-effects Selectable sample temperature between15ºc and 70ºC Unique algorithm for particle size calculation