Solubilizing side groups

As has been outlined above, a second, very fruitful synthetic principle for obtaining structurally homogeneous, processable PPP derivatives involves the preparation of soluble PPPs via introduction of solubilizing side groups. The pioneering work here was carried out at the end of the eighties by Schluler, Wegner, et al. [11, 121, who for the first lime prepared soluble poly(2,5-dialkyl-1,4-phenylene)s 6. 

The polymerization of l,4-bis(halomethyl)benzenes to PPVs in the presence of a large excess of potassium f-butoxide is referred as the Gilch route [81]. The method was first described for the synthesis of unsubstituted PPV 60, but -unfortunately - this route produces the PPV as an intractable, insoluble powder. However, the adaptation of the Gilch route to the polymerization of l,4-bis(halo-methyl)benzenes possessing solubilizing side groups gives access to soluble PPV materials. 

Disklike rc-conjugated mesogen Mesogenic side group Flexible spacer Solubilizing side chain... 

One of the main advantages of water-soluble polyphosphazcncs is the ease with which water-solubilizing side groups can sufficiently cross-link in a stable matrix with high energy radiation such as x-rays, gamma-rays, electron beams, or ultraviolet light. 

The copolymerization of species having hydrophilic side groups with hydrophobic monomer units has led to the development of water-dispersible coatings of considerable promise. The morphology of these polymers and the orientation that takes place at the interface are of particular importance, for organic cosolvents are used in the copolymer synthesis and also as solubilizers. 

A synthetic sequence to poly(quinoxaline)s with (dialkylamino)vinyl substituents as solubilizing side-groups was developed by Yu and Dalton by combining the two approaches discussed [18, 19]. The condensation of a bis-(dialkylamino)vinyl-2,5-dichloro-l,4-benzoquinone (8) with tetraaminobenzene... 

The second approach to PPV, is the Gilch synthesis [147], which consists in the introduction of solubilizing side groups, as represented in the case of the most studied dialkoxy derivative poly[2-methoxy-5-(2 -ethylhexyloxy)-l,4-phenylene vinylene] (MEH-PPV, XII) [29,148-150] (Fig. 9.20). 

---