PEO Unsaturated Macromonomers

Poly(ethylene oxide) (PEO) macromonomers constitute a new class of surface active monomers which give, by emulsifier-free emulsion polymerization or copolymerization, stable polymer dispersions and comb-like materials with very interesting properties due to the exceptional properties of ethylene oxide (EO) side chains. They are a basis for a number of various applications which take advantage of the binding properties of PEO [39], its hydrophilic and amphipathic behavior [40], as well as its bio compatibility and non-absorbing character towards proteins [41]. Various types of PEO macromonomers have been proposed and among them the most popular are the acrylates and methacrylates [42]. 

A different behavior of monomeric and polymeric molecules (polymacromonomers) in aqueous solution was found which was discussed in terms of strong correlation between molar mass and solution structure. Amphiphilic molecules try to minimize the contact area of hydrophobic groups with water molecules. 

With monomeric molecules, the aggregation number of micelles is determined by equilibrium thermodynamics. In polymeric molecules, however, topological constraints are imposed on the system. If the degree of polymerization exceeds the aggregation number of the monomeric micelle, unsaturated sites of the polymeric molecules become available (directed to the aqueous phase) and inter-molecular interactions (agglomeration) occur. In the case of polymer with Mw= 6.23x105, typical surfactant behavior was found. 

The weight-average molecular weight (Mw), intrinsic viscosity ([r ] cirr3 g ), and hydrodynamic radius (Rh nm ) increase with increasing temperature. The second virial coefficient (A2) decreases with temperature 2.3 xlO mol cm3 g 1 at 10 °C and 0.8 xl0 4mol cm3 g 1 at 30 °C. 

The dependence of reduced viscosity on concentration is curved upward, which could be interpreted as entanglement of rod-like micelles and/or a strong micellar interaction [47]. The increase in microviscosity results mainly from the growth in micellar size [48]. 

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