Thermoplastic elastomers, synthesis

This chapter discusses synthetic polymers based primarily on monomers produced from petroleum chemicals. The first section covers the synthesis of thermoplastics and engineering resins. The second part reviews thermosetting plastics and their uses. The third part discusses the chemistry of synthetic rubbers, including a brief review on thermoplastic elastomers, which are generally not used for tire production but to make other rubber products. The last section addresses synthetic fibers. 

Phthalazinone, 355 synthesis of, 356 Phthalic anhydride, 101 Phthalic anhydride-glycerol reaction, 19 Physical properties. See also Barrier properties Dielectric properties Mechanical properties Molecular weight Optical properties Structure-property relationships Thermal properties of aliphatic polyesters, 40-44 of aromatic-aliphatic polyesters, 44-47 of aromatic polyesters, 47-53 of aromatic polymers, 273-274 of epoxy-phenol networks, 413-416 molecular weight and, 3 of PBT, PEN, and PTT, 44-46 of polyester-ether thermoplastic elastomers, 54 of polyesters, 32-60 of polyimides, 273-287 of polymers, 3... 

The synthesis of well defined block copolymers exhibiting controlled molecular weight, low compositional heterogeneity and narrow molecular weight distribution is a major success of anionic polymerization techniques 6,7,14-111,112,113). Blocks of unlike chemical nature have a general tendency to undergo microphase separation, thereby producing mesomorphic phases. Block copolymers therefore exhibit unique properties, that prompted numerous studies and applications (e.g. thermoplastic elastomers). 

FIGURE 5.2 Synthesis of polyisobutylene (PIB)-based star-block thermoplastic elastomer (TPE). (From Jacob, S. and Kennedy, J.P., Adv. Polym. Sci., 146, 1, 1999.)... 

Varshney S.K. et al.. Synthesis of ABA type thermoplastic elastomers based on poly acrylates. Macromolecules, 32, 235, 1999. 

Yu J.M., Dubios P., and Jerome R., Synthesis and properties of polypsobomylmethacrylate (IBMA)-b-butadiene (BD)-b-IBMA] copolymers New thermoplastic elastomers of a large service temperature range. Macromolecules, 29, 7316, 1996. 

Puskas, J.E. et al. Synthesis and characterization of novel dendritic (arborescent) polyisobutylene-polystyrene thermoplastic elastomers, J. Polym. Set A, 43, 1811, 2005. 

Controlled/living radical polymerisation (CRP) is currently a fast developing area in polymer synthesis and it allows preparation of many advanced polymeric materials, including thermoplastic elastomers, surfactants, gels, coatings, biomaterials, materials for electronics and many others. 

A wide variety of such topics are covered in this book. Most of the chapters are from papers presented at a symposium held in August 1981. This symposium was preceded by a half-day tutorial session, with corresponding introductory review articles on synthesis of elastomers by G. Odian and rubber elasticity by J. E. Mark (published in the November 1981 issue of the Journal of Chemical Education). To aid the reader, a brief review of thermoplastic elastomers is included in this book. 

To sum up, the living character of the aluminum alkoxide mediated ROP of lactones has permitted the synthesis of novel ABA triblock copolymers, the composition and molecular weight of which can purposely be tuned up for displaying excellent elastomeric properties. Interestingly, the inherent biodegradability of each partner, PCL and PDXO, would open up new applications for these novel thermoplastic elastomers. 

Condensation polymerization and stepwise addition polymerization are, for example, applied for the preparation of block polyesters. The synthesis concepts are different from those of chain polymerization in that at least one monomer is an oligomer with one or two functional end groups, for example polytetrahy-drofurane with a molecular weight of several hundred and OH-end groups (see Example 3-23). If this oligomer partially replaces butandiol in the condensation polymerization with terephthalic acid (compare examples 4-1 and 4-2), a po-ly(ether ester) is obtained with hard ester segments and soft ether segments and with the properties of a thermoplastic elastomer. 

There is a growing interest in the synthesis of star-block thermoplastic elastomers (TPEs) on account of their unique mechanical and rheological properties [71-73]. PIB-based TPEs exhibit excellent mechanical properties and have superior thermal and oxidative stabiHties relative to polydiene-based TPEs [73,74]. 

One of the most important discoveries relating to synthesis and physical behavior was made by Dr. Milkovich while at the Shell Development Co. He and his colleagues showed that triblock copolymers containing polystyrene-polydiene-polystyrene blocks in appropriate sizes could behave as a physically cross-linked but linear thermoplastic elastomer. Thus Dr. Milkovich was involved with two very crucial discoveries in this field. Interestingly, he received his M. S. degree at Syracuse with Professor Szwarc and his Ph.D. at Akron with Professor Morton. I was pleased that Dr. Milkovich accepted my invitation to be a plenary speaker at the symposium, along with Professors Szwarc and Morton. 

Z. Fodor and R. Faust, Polyisobutylene-based thermoplastic elastomers. IV. Synthesis of poly (styrene-block-isobutylene-block-styr-ene) triblock copolymers using n-butyl chloride as solvent, J. Macromol. Sci.-Chem., 33(3) 305-324, March 1996. 

The nonterminating nature of living anionic polymerization allows the synthesis of block copolymers,480,481 which are useful thermoplastic elastomers. They have many properties of rubber (softness, flexibility, resilience) but in contrast to rubber can be processed as thermoplastics 482,483 Block copolymers can be manufactured by polymerizing a mixture of two monomers or by using sequential polymerization. 

In the 1960s, anionic polymerized solutron SBR (SSBR) began to challenge emulsion SBR in the automotive tire market. Organolithium compounds allow control of the butadiene microstructure, not possible with ESBR. Because this type of chain polymerization takes place without a termination step, an easy synthesis of block polymers is available, whereby glassy (polystyrene) and rubbery (polybutadicnc) segments can be combined in the same molecule. These thermoplastic elastomers (TPE) have found use ill nontire applications. 

The "living characteristic of lithium initiators is uniquely suited to synthesis of block copolymers. A rapidly growing new type of thermoplastic elastomer market is based on this technology. 

The synthesis, characterization, and mechanical properties of a novel star block copolymer thermoplastic elastomer with eight poly(isobutylene-b-sty-rene) arms radiating from a calix[8]arene was recently reported by Jacob et al. [41]. The process involved the synthesis of eight arm star PIB by a method essentially identical to that described above, followed by sequential addition of S after the IB conversion has reached 95%. To minimize alkylation and to obtain high MW PS blocks, moderate TiCl4 concentration (0.059 mol 1 x) and a 2- to... 

The species -O-N-R in the scheme is a stable organic radical called a nitroxide, one type of radical that does not react with itself but which reacts with carbon radicals forming weak C-O-N bonds. This approach continues to develop and allows the synthesis of polymers with very narrow molar mass distributions, block copolymers, and polymers with different architectures such as highly branched materials (discussed shortly). This is but one of a limited number of techniques that show promise for producing improved thermoplastics, elastomers, and adhesives for packaging and automotive applications (Anon. 2002). 

Poly (iso butylene) glycol is a suitable rubbery segment in thermoplastic elastomers. An oligomer such as 56 with a tertiary chloro group at both ends could be employed also as the initiator of cationic polymerization of a-methylstyrene (a-MeSt) in the synthesis of a three-block copolymer of poly(a MeSt)-polyisobutylene-poly(a-MeSt)52). 

Title Synthesis of Energetic Thermoplastic Elastomers Containing Both Polyoxirane and Polyoxetane Blocks... 

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