Polybutadiene, hydroxyl preparative method

Reed 332) has reported that reaction of ethylene oxide with the a,(a-dilithiumpoly-butadiene in predominantly hydrocarbon media (some residual ether from the dilithium initiator preparation was present) produced telechelic polybutadienes with hydroxyl functionalities (determined by infrared spectroscopy) of 2.0 + 0.1 in most cases. A recent report by Morton, et al.146) confirms the efficiency of the ethylene oxide termination reaction for a,ta-dilithiumpolyisoprene functionalities of 1.99, 1.92 and 2.0j were reported (determined by titration using Method B of ASTM method E222-66). It should be noted, however, that term of a, co-dilithium-polymers with ethylene oxide resulted in gel formation which required 1-4 days for completion. In general, epoxides are not polymerized by lithium bases 333,334), presumably because of the unreactivity of the strongly associated lithium alkoxides641 which are formed. With counter ions such as sodium or potassium, reaction of the polymeric anions with ethylene oxide will effect polymerization to form block copolymers (Eq. (80) 334 336>). 

The x,x -azobis(x-cyano-alkanol)s are prepared by the Strecker synthesis followed by oxidation of the hydrazo intermediate. The same method was also used for 4,4 -azobis(4-cyano-n-pentanol) and 5,5 -azobis(5-cyanohexane-2-ol). The former one was a good initiator for secondary hydroxyl-terminated polydienes. Similar results were reported by Reed (see Sect. 1.1.2. a) for hydroxytelechelic polybutadienes (the functionality was 1.9 to 2.5, generally higher than 2, M < 5000). 

Reed has reported that reaction of ethylene oxide with the a,(a-dilithiumpoly-butadiene in predominantly hydrocarbon media (some residual ether from the dilithium initiator preparation was present) produced telechelic polybutadienes with hydroxyl functionalities (determined by infrared spectroscopy) of 2.0 + 0.1 in most cases. A recent report by Morton, et al. confirms the efficiency of the ethylene oxide termination reaction for a,ta-dilithiumpolyisoprene functionalities of 1.9, 1.92 - i reported (determined by titration using Method B of ASTM... 

Ethylene polymerized with diethyl peroxydicarbonate contains terminal ester groups (41). Using C-labeled cyclohexane peroxydicarbonate, the fate of the primary radicals during the polymerization of methyl methacrylate (MMA) and styrene has been studied (42). Although this reference includes no detailed analysis of the products, it indicates that ROOCO-terminated polystyrene telechelics may be obtained by this technique. A similar method has been used for the preparation of telechelic polybutadiene (43). The carbonate end groups are easily modified into terminal hydroxyl groups by hydrolysis. Hydrogenation of the carbonate functionahzed telechelic polybutadiene, followed by hydrolysis, srields hydroxy-terminated polyethylene telechelics. 

The preparation of hydroxyl-terminated polybutadiene (HTPB) by free radical methods is not well documented. As shown in Table 5, four commercial organizations in the United States suppUed these products in 1968. Two of these use ionic polymerization, and of the remaining two, Goodrich and Sinclair, Goodrich is believed to use a free radical method of preparation. The method of production of Sinclair s product is not known. 

Hydroxyl-terminated polybutadiene can be prepared from polymers having two living ends by addition of oxides, aldehydes, or ketones [279,282,285]. HTPB prepared by ionic methods is commercially available from Phillips Petroleum Company and General Tire and Rubber Company. The former supplies a secondary hydroxyl-terminated product and General Tire and Rubber Company produces both primary and secondary hydroxyl-terminated polybutadiene. 

---