I am dissolving two polymers in a single solvent and then combine them together form single solution and cast it as a membrane using solvent casting method.. Main aim is to form a polymer blend.
How i can confirm wheater the prepared membrane is a polymer blend or not ?
Many polymers do not blend. Typically, only polymers which have a ”good” interaction with each other will blend As the solvent evaporates from your solution, the polymers will often tend to associate with like polymers so that you will have domains made of polymer A and domains made of polymer B but not a nearly homogeneous blend. Various microscopy techniques may be able to image the micro domains - depending on the size of the domains and the polymers it may require SEM or TEM or some type of elemental analysis like EDX. Scattering from the domain boundaries may also be used. If you are unable to visualize the domains it is harder to prove a blend exists - I have seen solid state NMR used but that is pretty specialized…. You might want to look into DSC - domains that are pure A or pure B should retain the Tg and Tm of the bulk phases but a true blend would have a new set of thermal properties.
Dear all, you can find full information in the following book. My Regards
https://www.wiley.com/en-us/Characterization+of+Polymer+Blends%3A+Miscibility%2C+Morphology+and+Interfaces-p-9783527331536
It depends on whether you are looking for a genuine thermodynamic mixture (i.e., a single phase) or a heterogeneous phase-separated blend. The first one is hard to achieve since polymers are generally poorly miscible, as James E Hanson mentioned. Therefore, the second case is probably much more common. When selecting an experimental technique for quantifying the domain size, you must consider two parameters - resolution and contrast.
For instance, Tg measured by DSC could determine if the polymers are genuinely mixed (see James E Hanson's comment), but it cannot measure the domain size. Optical incompatibility is probably the easiest method. It is based on differences in refractive index, transparency, etc. You can use an optical microscope, but the wavelength of the detected light limits the resolution.
Spectroscopic microscopy (FTIR, Raman) could be used to quantify domains with a resolution of approx several microns (Raman with green or UV laser) to tens of microns (FTIR, Raman with IR laser).
Article Application of FTIR Microscopy in Combinatorial Experimentat...
SEM/TEM has a good resolution, but you must consider the contrast. EDS is one option, but it will not do for polymers with similar elemental compositions, such as PP/PE blends. Also, note that the EDS signal comes from a much larger interaction volume than the SE or BSE used for topography observation. You often have to use a larger beam intensity to gain enough signal, which further increases the interaction volume. Selective etching by a chemical agent is another common way of visualizing the blend composition in SEM/TEM.
You can also use X-ray diffraction, but resolving the data might not be as straightforward as in other techniques.
Article Characterization of Polymer Blends by X-Ray Scattering: SAXS and WAXS
AFM/SPM is another good pick. You can use either AFM's oscillation-mode phase contrast, electric force probe
Article Electric force microscopy of dielectric heterogeneous polymer blends
or Kelvin probe.
Article Scanning Kelvin Probe Microscopy on Bulk Heterojunction Polymer Blends
There are several methods that can be used to confirm the blending of two polymers. Some common methods include:
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