Hillmyer and Hartwig et al. Results and Discussion. We have recently developed a copper-based catalytic system for the functionalization of alkanes through insertion of CHCO2Et into C—H bonds using commercial ethyl diazoacetate EDA as the carbene source.
The polymerization of transbutene with a-di-imine Ni II catalysts11 provides a high molecular weight polyolefin with a well-defined structure corresponding to a linear polyethylene with a methyl branch on every third carbon atom precisely Scheme 1. We have carried out the room temperature reaction of ethyl diazoacetate and the poly 2-butene 12 in the presence of catalytic amounts of TpBr3Cu NCMe Scheme 1.
Table 1. Mw and Mn values x 10 3 g mol. Figure 1 shows the 1H NMR spectrum of the functionalized polymer. The degree of incorporation determined by NMR was ca.
US20080045683A1 - Polyolefin Treatment for Separating Volatile Material - Google Patents
A significant feature of this methodology was revealed by GPC of the functionalized materials Table 1, entries 1—3. Note that molecular weights are apparent molecular weights relative to linear polyethylene standards; i. As shown in Figure 1, the 1H NMR spectrum13 of the modified polymer displays again the resonances attributable to — CH2—CO2Et groups with similar patterns to those observed in the functionalization of smaller alkanes.
The existence of a large. Figure 2. This could also account for the observed increase in the degree of ester group incorporation in terms of the number of carboxylates per C , as inferred from the data in entries 3 and 9 in Table 1. These results are in good agreement with the observed regioselectivity in the case of 2-methylbu-tane and 2-methylpentane. Since control of the degree of ester incorporation is desirable due to its relationship to polymer properties, we have performed a series of experiments where we have modified the following variables: i EDA addition time, ii catalyst loading, and iii polymer:EDA ratio Table 1, entries 4— Although each of them exerts a certain degree of influence in the number of :CHCO Figure 3.
Left: polymer repeat units:EDA Right: polymer repeat units:EDA , incorporation: 2.
A multi-scale tool for functionalization of polyolefins through radical grafting
Et groups incorporated, the EDAipolymer ratio seems to be the predominant factor. Figure 2 shows the variation of the degree of incorporation, at a fixed addition rate and catalyst loading, with respect to such ratio, for the poly ethylene-co-l-octene case: it is quite evident that this system enables control of the number of ester groups incorporated into the polymer chain.
Functionalization of an atactic, saturated polypropylene oligomer Mn vs polystyrene standards was also studied. Whereas IR detection is nonspecific, the UV detection is selective for the ester groups introduced. In conclusion, the results described herein represent a new method to introduce polar ester groups into polyolefin chains, distinct to all those reported to date in operating under mild conditions without any observable chain scission in a one-step procedure.
The versatility of the method has been demonstrated also for a commercial standard polyolefin. Support by a DAAD travel grant is acknowledged. Reviews: d Ittel, S.
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Functionalization of Polyolefins
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