Polyisobutylene diol

This paper concerns the synthesis of a new telechelic polyisobutylene diol, a, a)-di (hydroxy) po lyi so-butylene (formula IV in Scheme I), and the preparation of new linear polyurethanes containing polyisobutylene (PIB) soft segments by the use of this diol and conv-ventional extension techniques with TDI. 

Chain extension of polyisobutylene diols have been carried out with TDI under a dry N2 atmosphere in a stainless steel enclosure at a.80°C on a heating plate. The diol containing a trace amount of DBTDL catalyst and TDI (NCO/OH 1.0) were rapidly mixed with a glass rod and the charge was maintained at 78-80° for two days. Molecular weights were determined by GPC the equipment and procedure used have been described [1]. 

A. Synthesis of Linear Telechelic Polyisobutylene Diols. According to model calculations [5-7] efficient chain extension of telechelics can be carried out only with prepolymers having (number average... 

In conclusion, these experiments indicate the possibility of synthesizing polyurethanes with polyisobutylene soft segments. The polyisobutylene diols have been synthesized by the inifer method and careful characterization techniques indicate Fn = 2.0. It is anticipated that polyurethanes with polyisobutylene soft segments will exhibit superior thermal, UV, oxidative and chemical resistance to conventional polyurethanes having polyester, polyether, or polybutadiene soft segments. 

Common SS include polyethers, polyesters and polyalkyl glycols with glass transition temperatures in the range of -70°to -30°C. Commonly used macrodiols in the PUs synthesis are polyalkyl-diols, such as polyisobutylene diol [70], polybutadiene (PBU) [20, 71], or oligo-butadiene diols [72] as well as hydrogenated polybutadiene diol [20] polyether diols polytetrahydrofuran (PTHF or PTMO) [50-52], polyethylene glycol (PEG) or (PEO) [73], polypropyleneoxide (PPO) [73] or mixed blocks of them PEO-PPO-PEO [74] and PPO-THF [54] polyester diols poly(ethylene adipate) (PEA) [4,20], poly(butylene adipate) (PBA) [20, 73], and latterly polycaprolactone diol (PCL or PCD) [75], polyalkylcarbonate polyol [20] or mixed blocks of them, for example poly(carbonate-co-ester)diol [76], poly(hexamethylene-carbonate)diol [77], as well as poly(hexamethylene-carbonate-co-caprolactone)diol [78] and a mixed block copolymer of polyether and polyester blocks PCL-b-PTHF-b-PCL [79]. Examples schemes of macrodiols are shown in Eig. 1.9. 

The processes described in Table 2 present a peculiar interest in the working out of new materials as polyurethanes. These last polymers are very often based on macro diols coming from polyethers or polyesters, a-co functional polyolefins being relatively uncommon. Hence, Rhein and Ingham [139] prepared macrodiols by ozonization of polyisobutylene in CC14 at... 

THF) of the chlorine-terminated products led to olefin telechelic derivatives which in turn yielded many potentially useful materials (14). Thus hydroboration (a quantitative reaction) gave rise to new polyisobutylene-based diols and triols which in combination with isocyanates gave unique polyurethanes ... 

Scheme I. Synthesis of polyisobutylene-based diols and polyurethanes.

A novel polyisobutylene-based diol has been synthesized and subsequently used in conjunction with tolylene diisocyanate (TDI) to yield polyurethanes. 

Speckhard T, et al. Properties of polyisobutylene polyurethane block copolymers 3. Hard segments based on 4, 4 -dicyclohexylmethane diisocyanate (H12MDI) and butane diol. Polymer 1985 26(l) 70-8. 

Cross-linking can be done by various techniques depending on the chemical composition of the polymer. Thus, if the polymer contains C=C unsaturation, e.g. in polydienes, natural rubber, polyisobutylenes (from copolymerized isoprene), then reaction with sulphur forms —S—S— links. With polysiloxanes or EP rubbers (no C=C) then peroxides are used. With fluorocarbon elastomers, e.g. Viton (a copolymer of vinylidene difluoride and hexafluoropropylene), diamines are used which form H-bonded cross-links. With polyurethanes (formed from diols and di-isocyanates) a controlled number (low) of cross-links are formed during the polymerization by the addition of triols. 

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