Small-angle neutron scattering branches

In t-DVB/S copolymerization, Antonietti and Rosenauer isolated microgels slightly below the macrogelation point [221]. Using small angle neutron scattering measurements they demonstrated that these microgels exhibit fractal behavior, i.e. they are self-similar like the critically branched structures formed close to the sol-gel transition. 

Characterization of Dendritically Branched Polymers by Small Angle Neutron Scattering (SANS), Small Angle X-Ray Scattering (SAXS) and Transmission Electron Microscopy (TEM)... 

Plestil, J. Pospisil, H. Sikora, A. Krakovsky, K.A.I. Small-angle neutron scattering and differential scanning calorimetry study of associative behaviour of branched poly(ethylene oxide)/poly(propylene oxide) copolymer in aqueous solution. Journal of Applied Crystallography 2003, 36, 970-975. 

Fig. 1.17 Small-angle neutron scattering pattern for a sample of per-deuterated lightly branched polyethylene containing 10% of hydrogen containing linear polyethylene. The sample is molten and has just been subjected to deformation in a channel die. The flow axis is horizontal and the effective extension ratio is 3.

Many LLDPE are compositionally heterogeneous, since they contain molecules with few branches and molecules that are highly branched. The more highly branched fraction can be separated by solvent extraction. Small-angle neutron scattering (SANS) has confirmed the prediction that stmcturally disperse LLDPE display liquid-liquid phase separation, even if the overall branch content is low. These LLDPE behave like polyethylene blends even though they are the result of a single polymerization. 

Relations (6.10) and (6.11) were tested experimentally by small angle neutron scattering. Let us mention that starshaped polymers are in this same universality class the mass dependence of their radius of gyration also follows relations (6.10). However, it also depends on the number/of branches, indicating the special geometry of the object. For more details, the reader is referred to Refs. [21-25]. 

Bauer BJ, Amis EJ (2001) Characterization of dendritically branched polymers by small angle neutron scattering (SANS), small angle X-ray scattering (SAXS), and transmission... 

Habas and co-workers [43] carried out an investigation into the viscoelastic properties of aqueous solutions of a four-branched polyethylene oxide - polypropylene oxide - polyethylene oxide triblock copolymer in the unimer range using TMA, DMTA and small-angle neutron scattering. The aqueous solutions were characterised in the crystalline phase and a modified version of Eyring s theory was used to describe the stress-time dependence of ordered solutions. 

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