Polybutadiene telechelic

Alternatively, end-functionalization of growing chains can also be obtained via transfer in chain addition polymerization. For instance, dihydroxy polybutadiene telechelics (i.e. carrying one hydroxyl group at each chain-end) are industrially produced by free radical polymerization of butadiene initiated by hydrogen peroxide which simultaneously gives rise to transfer reactions ... 

In order to prove that intramolecular cyclization occurs before telechelic oligomer formation, an experiment similar to previous work by Calderonlf is performed using 14 in place of Calderon s classical catalyst system. Macrocyclic species are formed when a toluene solution of polybutadiene is exposed to this catalyst, supported by both NMR and GC data. The vinylic resonances are clearly shifted upfield from polybutadiene. GC analysis shows macrocyclic trimers and tetramer regioisomers. 

TDI isomers, 210 Tear strength tests, 242-243 TEDA. See Triethylene diamine (TEDA) Telechelic oligomers, 456, 457 copolymerization of, 453-454 Telechelics, from polybutadiene, 456-459 TEM technique, 163-164 Temperature, polyamide shear modulus and, 138. See also /3-transition temperature (7)>) Brill temperature Deblocking temperatures //-transition temperature (Ty) Glass transition temperature (7) ) Heat deflection temperature (HDT) Heat distortion temperature (HDT) High-temperature entries Low-temperature entries Melting temperature (Fm) Modulu s - temperature relationship Thermal entries Tensile strength, 3, 242 TEOS. See Tetraethoxysilane (TEOS)... 

These results indicate that if polydienes and similar polymers can be prepared quantitatively with tertiary amine terminal groups, then they can be combined with other halogen functional polymers using established techniques to create interesting new block copolymer systems. For example, consider the reaction between telechelic pyridine terminated polybutadiene and monofunctional bromine terminated polystyrene (equation 4) -the latter has been prepared in 95% yield. >it The product would be an ABA... 

The successful synthesis of such materials requires that, Initially, telechelic tertiary amine terminated polybutadiene be prepared quantitatively. Alternative routes are therefore being sought, two of which are outlined In this paper. 

Anionic polymerization has also been used to make telechelic polymers (Greek telos, end, and chele, claw), i.e., polymers with reactive terminal groups.We coined the term, telechelic in 1957 and it has been accepted ever since in technical as well as patent literature. Liquid carboxy- and hydroxy telechelic polybutadienes initiated with difunctional organolithium initiators are commercially produced since 1962. Some of the physical properties,production details and uses as in solid rockets... 

Fig. 17. Addition product of tetra-n-butoxy-titanium to carboxy telechelic polybutadiene...

Telechelic Polybutadiene Hycar Goodrich Sulfonated ethylene-propylene... 

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>). 

Here, x and y stand for the weight fraction of 1,2 and 1,4 units, respectively. On the other hand, commercial hydroxy-telechelic polybutadiene obtained by radical... 

Figure 11.12 JH-NMR spectrum of hydroxy-telechelic polybutadiene, observed at...

The functionality of hydroxy-telechelic polybutadiene and polyisoprene was determined by -NMR after modification with phenyl isocyanate or naphthyl isocyanate. Liquid telechelic polybutadiene and polyisoprene, prepared by choosing appropriate reaction conditions, showed Fn value of about 1.9, which agreed with the values determined by titration method [69]. 

Amino-terminated telechelic polybutadiene was prepared by LiAlH4 reduction of amidino end-group in polybutadiene, which was polymerised by a water-soluble initiator, 2,2 -azobis(amidinopropane)dihydrochloride. The structure was analysed by 1H- and 13C-NMR, but functionality of 2.0 was obtained by a titration method [70]. Synthesis of co-epoxy-functionalised polyisoprene was carried out by the reaction of 2-bromoethyloxirane with living polymer that was initiated with sec-butyl lithium. The functionality of the resulting polyisoprene was 1.04 by 1H-NMR and 1.00 by thin layer chromatography detected with flame ionisation detection [71]. 

The terminal hydroxyl groups in hydroxy-telechelic polybutadiene are assumed to be predominantly primary alcohols linked to c/s-1,4, trans-1,4, and 1,2 butadiene units [72], Detailed structure of the butadiene or isoprene units at both terminals was studied by the use of 2H-NMR [73], as shown in Section 6.1... 

It is possible not only to achieve high mass conversions of polybutadiene to 1,5-hexadiene but also to create telechelic oligomers in this manner [38-40]. Catalyst selection plays an important role here ruthenium-based catalysts appeared to be best in bringing about clean conversions of high molecular weight unsaturated polymers to their telechelic oligomers [1]. 

The functional initiators were prepared many years ago and were used for the synthesis of polybutadiene carboxy telechelic by the Thiokol Company [74] according to the following scheme ... 

As an example of first block obtained by ionic polymerization, Tung et al. [118] have synthesized an a,co-polybutadiene, the end-groups of which were deactivated onto episulfide in order to generate a telechelic polybutadiene dithiol. Such a compound was successfully used to initiate the copolymerization... 

ADMET depolymerizations with substituted alkenes have been done as well, thereby generating perfectly difunctional telechelic molecules. As an example, 1,4-polybutadiene has been depolymerized in an inert atmosphere with a 10-fold molar excess (based on the repeat unit) of either allyltrimethylsilane or allylchlorodimethylsilane (equation 23). In these examples, the chemistry can be driven to complete depolymerization to yield structures with either one, two, three, or four repeat units of 1,4-butadiene. The synthesis of perfectly difunctional oligomers by this chemistry offers significant opportunity, particularly for functional groups such as alcohols, esters, carboxylic acids, and amines. 

Elastomers are prepared by chain extension of hydroxyl-terminated low-molecular-weight polymers followed by vulcanization 180). The most important work concerns the use of hydroxy telechelic polybutadienes and polyisoprenes in the tire industry 249 252>. The hydroxylated polydienes of molecular weight 1000-20000 are mixed with a diisocyanate, a catalyst, vulcanization agent (sulfur), and accelerator, reinforcing additives (carbon black), and surface-active agents. The reaction takes place in two steps simultaneously or consecutively ... 

Several interesting applications can be envisioned on the basis of that behaviour, but again saturated-elastomers will be more suitable for most of them, in terms of ageing. Here again, hydrogenated telechelic polybutadiene is a possible answer to that problem although telechelic polyisobutene might alternatively be used in some cases. 

AIBN can be quantitatively converted to azo-esters. Bulk polymerization of butadiene with azo-esters results in the formation of telechelic polybutadiene with ester end-groups. 

Polymer Preparation. Two bifunctional (telechelic) polymers were used in this study. Carboxy-telechelic polybutadiene (PB) is commercially available from B. F. Goodrich (Hycar CTB 2000X156) with molecular characteristics of Mn=4,600, Mw/Mn= 1.8, functionality 2.00 and cis/trans/vinyl ratio of 20/65/15. Carboxy-telechelic polyisoprene (PIP) was prepared by anionic polymerization in THF at -78°C with a-methylstyrene tetramer as a difunctional initiator. The living macrodianions were deactivated by anhydrous carbon dioxide. Five polymers werejjrepared with Mn=6,000 10,000, 24,000, 30,000 and 37,000 having Mw/Mn=sl.l5 a microstructure ratio of 3, 4/1, 2 of 65/35, respectively, and a functionality >1.95. 

Solomon et al. [203] developed a technique allowing the terminal aminoxyl to be replaced by a hydroxyl function. With this aim, they reacted the terminal aminoxyl containing oligomer with acetic acid catalyzed by zinc. Pradel et al. [218] achieved the synthesis of hydroxy-telechelic polybutadiene by applying the methodology of Solomon et al. to a-hydroxyl/o-aminoxyl polybutadiene (the synthesis was presented earlier) at 80 °C. After 2 h, they obtained a quantitative reduction of the aminoxyl functions evidenced by ll NMR (Scheme 38). The average hydroxyl functionality of oligobutadiene was 2.06. 

Another variant for the synthesis of hydroxy telechelic polybutadiene is based on the anionic living polymerisation of butadiene, using sodium naphthalene as catalyst [16]. Sodium naphthalene generates, by reaction with butadiene, a radical anion (9.8). If two of these radicals are coupled together, they generate a dianion (9.9), which is an ideal bifunctional initiator for the synthesis of perfectly bifunctional polybutadiene by anionic polymerisation. 

Using the same approach, ABA block copolymers (with TBA segments forming block A) were prepared using bifunctional telechelic amino- or carboxy-terminated polybutadiene or poly(butadiene-co-acrylonitrile). The latters are commercially... 

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