P-Divinyl benzene

Immobilized cryptates. Like the crowns, cryptates have been immobilized on polymeric backbones. A typical system is given by (221) (Cinquini, Colonna, Molinari, Montanari Tundo, 1976). In this case, the polymeric matrix is polystyrene cross-linked with p-divinyl benzene and the cage is connected to this matrix via a long-chain aliphatic spacer group. This reagent is quite effective as a (triphase) transfer catalyst. 

Figure 10. Thermal polymerization of styrene-p-divinyl benzene at 70°C optimum for popcorn polymer formation...

The alternating copolymers (PPOX-CAR and PMOX-CAR) are easily prepared by the Wittig condensation polymerization between the oxadiazole containing salt monomers and the carbazole dialdehyde. The copolymer, PPOXPV, composed of oxadiazole unit and phenylenevinylene unit, can be prepared by the same way as shown in Scheme 10. But the kinked PPOXPV copolymer is prepared in different synthetic pathway. Reaction of bis(2-bromo-5-hexyloxyben-zyl)-l,3,4-oxadiazole with p-divinyl benzene results in the formation of POOX-PV copolymer [69]. 

Polyfunctional polybutadienyldilithium anions have been used to prepare ABA block copolymers of butadiene-styreneCl jl5) and butadiene-a-me thy 1 styrene(l )containing rubbery center blocks. Comparable block copolymers of butadiene-a-methyl styrene with a-methyl styrene center blocks have also been reported(19,20). In a similar preparation, Worsfold has capped an isoprene-a-methyl styrene block copolymer with p-divinyl benzene(21). This polymer is capable of further copol3nnerization. 

The opposite effect, namely that of stiffening a material by interlinking may be referred to here. In the case of polystyrene this can be effected by means of p-divinyl benzene, / CH = CH2 having two double bonds, leading to the inter-... 

METATHESIS POLYCONDENSATION OF SUBSTITUTED p-DIVINYL-BENZENES A WAY TO EASILY PROCESSABLE /i-PHENYLENEVINYLENE (PV) OLIGOMERS WITH VALUABLE PROPERTIES... 

The solubility may also be used to determine whether cross-linking of pol3rmer chains to a three-dimensional network has occurred. A network cannot actually disperse, although it may undergo intense swelling. Polystyrene is a linear polymer, and therefore soluble but when a small amount of p-divinyl benzene is added, the interpolymer, due to cross-linking of the polystyrene chains by p-divinyl benzene bridges, becomes insoluble (27). 

Fig. 50 Activation energies for oxidation obtained from different kinetic characteristics for thermal oxidation of butadiene a-methyl styrene copolymer (black), poly(p-divinyl benzene (grey) and polystyrene (white). The data were taken from [06J2].

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