Amide-containing block copolymers

Block copolymers can contain crystalline or amorphous hard blocks. Examples of crystalline block copolymers are polyurethanes (e.g. B.F. Goodrich s Estane line), polyether esters (e.g. Dupont s Hytrel polymers), polyether amides (e.g. Atofina s Pebax grades). Polyurethanes have enjoyed limited utility due to their relatively low thermal stability use temperatures must be kept below 275°F, due to the reversibility of the urethane linkage. Recently, polyurethanes with stability at 350°F for nearly 100 h have been claimed [2]. Polyether esters and polyether amides have been explored for PSA applications where their heat and plasticizer resistance is a benefit [3]. However, the high price of these materials and their multiblock architecture have limited their use. All of these crystalline block copolymers consist of multiblocks with relatively short, amorphous, polyether or polyester mid-blocks. Consequently they can not be diluted as extensively with tackifiers and diluents as styrenic triblock copolymers. Thereby it is more difficult to obtain strong, yet soft adhesives — the primary goals of adding rubber to hot melts. 

One of the most important uses of end-functionalized polymers is the preparation of block copolymers.73,74 The reactions are identical to the chain extensions already mentioned, except that the sequences being joined are chemically different. In the case of the -OSilCR Y chain ends mentioned above, R is typically (CH2)3 5 and Y can be NH2, OH, COOH, CH=CH2, and so on The siloxane sequences containing these ends have been joined to other polymeric sequences such as carbonates, ureas, urethanes, amides, and imides. 

Block copolymers of vinyl acetate with methyl methacrylate, acrylic acid, acrylonitrile, and vinyl pyrrolidinone have been prepared by copolymerization in viscous conditions, with solvents that are poor solvents for the vinyl acetate macroradical (123). Similady, the copolymerization of vinyl acetate with methyl methacrylate is enhanced by the solvents acetonitrile and acetone and is decreased by propanol (124). Copolymers of vinyl acetate containing cyclic functional groups in the polymer chain have been prepared by copolymerization of vinyl acetate with IV,IV- diallylcyan amide and N,N-diallylamine (125,126). 

A polymeric initiator with terminal halogen containing groups can be prepared by using a bifimctional initiator 4,4 -azobis(4-cyanopentanoic acid-trichloroacetyl-amide) (ACPT) [142]. When this polymer is irradiated at 436nm in the presence of Mn2(CO)io and the appropriate monomer, block copolymers are obtained [143], according to Scheme 40 ... 

Tsubouchi and Yoshikawa [79] are concerned with pervaporation separation of benzene/cyclohexane mixtures using membranes based on polyamide/polyether block copolymers. It has been established that the separation factor increases with the increase in the polyamide component containing polar amide groups capable of forming hydrogen bonds e.g., the 1 1 block copolymer of polyamide 12 and polyoxyethylene has the benzene/cyclohexane separation factor /3p = 2.8 and the flux 2 = 300 g/m h a more rigid 3 1 polyamide 12/polyoxyethylene block copolymer has a much higher separation factor )8p = 5.0 and 2 = 80 g/m h. 

PLLA block copolymers with poly(amino acids] are a class of copolymers which contain both ester and amide linkages, referred... 

Acrylic elastomer Chlorotrifluoroethylene polymer EPDM rubber Ethylene/ethyl acrylate copolymer Polyvinyl chloride pPDI-PTMEG jSilicone elastomer Styrenated diphenylamine Styrene-ethylene/butylene-styrene block copolymer Tetrafluoroethylene/propylene copolymer gaskets, closure-sealing food containers Arachidyl-behenyl amide Azodicarbonamide Benzyl alcohol Butylene glycol Carbon, activated... 

Block copolymers containing EO units like poly(amide-b-ether) have been shown as a good material for this purpose. 

Polyolefin (PO = PP, HOPE, EPR, or PMP) was blended with an impact modifier, 0.1-5 wt% colorant and/or 5-50 wt% of opadfios, and a styrene-diolefin block copolymer, grafted with 1-6 mol% of acrylic acid, maleic anhydride, or snlftniale functionality (SEBS, SEPS, radial SEB, or SEP). To improve scratch resistance the blend contained 100-3,000 ppm Zn stearate and 16-22C fatty acid amide. The alloys were injection molded into parts showing impact, scratch, and abrasion resistance. They were used to manufacture interior trim for vehicles and in other applications where a scratch- and scuff-resistant plastic material is required ... 

Previous approaches towards peptide containing rod-coil block copolymers all used the coil polymer as macro-initiator for the NCA polymerization. The doubleheaded initiator can be used for both sequences - peptide first or vinyl polymer first. In the later case it is necessary to perform the ATR-polymerization with the initiator in the alloc-amide form, thus before the activation with Ni(COD)2 (see scheme 2). The activation step then has to be done after the polymerization, thus this sequence requires polymer end group modification. On the other hand if the NCA polymerization is done first no end group modifications are necessary and the peptide block is used as macro-initiator. 

Recently, we have found that acrylamide derivatives such as N-methylacrylamide-(NMAAm) and N-methylmethacrylamide (NMMAm) were polymerized by radical initiators in adequate solvents to form polymer microspheres, which contained the very stable propagating radicals of the amide monomers in high concentrations. Furthermore, the living polymer radicals were found to react readily with other vinyl monomers at room temperature, yielding block copolymers. We have also investigated these reactions by means of ESR. This article reviews our recent work on the formation of living propagating radicals, their reactions with vinyl monomers, and their use in block copolymer synthesis. 

As described above, when NMAAm or NMMAm is photo-polymerized in benzene at room temperature, the amide monomer is converted to polymer microspheres containing its living propagating radicals in high concentrations. These living radicals react easily with other vinyl monomers. These reactions can be applied to the synthesis of block copolymers. 

Block copolymers combing PBI with other types of macromolecular units have also been developed for superior membrane properties, as shown in Fig. 7.6. Two types of copolymers have been prepared, characterized, and evaluated as fuel cell electrolytes. One is the sulfcmated copolymer containing PBI and snUrmated polymer moieties for low temperature PEMs in both PEM fuel cells and direct methanol fuel cells (DMFCs) [123-126]. The other is the random copolymer containing PBI and poly(imine/ amide) moieties [127, 128]. For the sulfonated PBI copolymers, benzimidazole monomers... 

Lastly, mention will be made of two further amide block copolymer syntheses not mentioned above. The first employs living polymer anions from styrene, isoprene or methyl methacrylate to initiate the polymerization of isocyanates to diblock polymers containing nylon 1 sequences. In this approach, selective polymerization can be achieved at the unhindered isocyanate group of diisocyanates such as tolylene 2,4-diisocyanate to give products with pendant NCO groups (32) which are crosslinkable with diols to give tough resins. 

Strange enough, so far there are no books entirely devoted to condensation TPEs and the latter are considered only in chapters of more general works. The most important TPEs prepared by polycondensation are the subject of several chapters of this book polyester-based TPEs, poly(amide-6-ethers), polyurethanes, etc. However, some less known condensation TPEs are described in Chapter 2 metal-containing macrocycles as monomers, liquid crystalline side chains, metallo-supramolecular block copolymers, as well as the use of enzymatic catalysis or of microorganisms. 

The elemental analysis of C gave little information, since the compositions of the copolymer and the reactant mixture are identical. Its infrared spectrum showed that the reaction took place, since new absorption groups (amide) were observed. On the other hand, the SEC traces of the products obtained by processes I and II are almost identical, suggesting that they probably do not contain homopolymer because its content has little chance to be the same. The solubility of the block copolymers, of the initial oligomers, and of the corresponding homopolymers provides useful information, despite that it is mainly a qualitative property (Table 1). 

---