Copoly derivatives

The incorporation of fluorine atoms improves the solubility of aromatic condensation polymers without causing them to lose their high thermal stability and modifies the processability. Hexafluoroisopropylidene-unit-containing poly-(azomethine)s and copoly(azomethine)s are readily soluble in highly polar solvents such as DMAc, HMPA, and NMP, and they also dissolve completely in dichloromethane, chloroform, and THF, whereas poly(azomethine)s derived from 21 and 22 and having no fluorine atom are insoluble in these solvents.20 Accordingly, the solubility of aromatic poly(azomethine)s is remarkably improved by substituting isopropylidene units with fluorine atoms. 

These contributions between 1988 and 1997 set the stage for a wide variety of contributions in the field of porous materials derived from block copoly-... 

New polymeric solid supports have been devised, which include macroporous styrene-divinylbenzene containing large fixed pores, porous glass beads, insoluble carbohydrate polymers, poly(ethylene oxide), cross-linked derivatives of polyacrylamide resins, and graft copolymers of polystyrene and poly(ethylene oxide). The last two have been the most effective and widely used and have competed well with the original copoly(styrene-divi-nylbenzene) beads. 

Most of the resins used in batch synthesis are derivatives of 1% crosslinked copoly-(styrene-divinylbenzene) resin in the form of beads 50 to 100 p in diameter. These beads swell four to six times their dry volume in the solvents used in peptide assembly and during the chain elongation process the resin again may double its swollen volume. In batch synthesis, provided the proper size vessel is chosen, the increase in swollen volume is not a major concern. 

Kobayashi et al. reported the first synthesis of polymer-supported silyl enolates (thioketene silyl acetals) and their reactions with aldehydes for the preparation of 1,3-diol, / -hydroxy carboxylic acid, and /i-hydroxy aldehyde libraries (Scheme 10.37) [104]. In the presence of 20 mol% Sc(OTf)3, polymer-supported silyl enolate 42 derived from chloromethyl copoly(styrene-l% divinylbenzene) resin via 41 reacts smoothly with a variety of aldehydes. The resulting adducts can be easily purified by acid treatment and subsequent washing with water and organic solvents. The purified adducts are converted into 1,3-diols with LiBH4, -hydroxy carboxylic acids with NaOH, and -hydroxy aldehydes with DIBALH. This strategy has been used for efficient synfhesis of diverse monosaccharide derivatives [105]. 

Introduced by Blout et a , for use in peptide synthesis, the reagent is prepared as shown in Chart I by condensing copoly(ethylenemaleic anhydride) (I, Monsanto DX840) with hydroxylamine hydrochloride in DMF. BOC-a-amino derivatives of alanine, phenylalanine, threonine, methionine, leucine, etc., were synthesized in... 

Fig. 19. Phase diagram of copoly(ester-imide)s derived from 4-aminobenzoic acid trimellit-imide and phenylhydroquinone + isosorbide...

Polyimides, and derivative copolymers such as poly(ester-imide)s have been known for decades but none were reported before 1987 to contain lyotropic or thermotropic mesophases, except certain copoly(esterimide)s with three or more monomers [6,7]. 

Since 1991 Kricheldorf has published many other articles on liquid crystal polyesterimides. These include two series of thermotropic copoly(esterimides) derived from N-(3 -hydroxyphenyl)trimellitimide and 4-hydroxybenzoic acid or 6-hydroxy-2-naphthoic acid, in which the critical compositions for obtaining mesophases were discovered by varying monomer levels [34]. A series of homopoly(esterimide)s were synthesised from N-(4-carboxyphenyl)trimelliti-mide and various diacetylated linked diphenols. When the diphenol contained an ether or carbonyl linking group, mobile nematic phases were observed. Various naphthalene diols were also employed instead of the diphenol, but only the 2,7-dihydroxy naphthalene produced a nematic phase [35]. 

The author s work on polyimide synthesis and its use to derive MI values for polyimides has been described in the previous section [43, 45-46]. These are virtually the only strictly true mesogenic polyimides which have been reported in the literature to date. However, in addition, there have been many reports of modified copolyimides such as copoly(etherimide)s, copoly(amide-imide)s, co-poly(esterimide)s or copoly(imide-carbonate)s which are discussed below. 

Equation (7.52) can also be derived from Eq. (7.43) by eliminating radical concentrations with the help of two steady-state assumptions written as Eqs. (7.44) and (7.47) and then using the definitions of ri and r2. Equation (7.52) represents a one-parameter model for the copoly merization rate (Melville et al., 1947) containing the parameter (p. Statistically, (p is expected to equal unity. However, the values of (p obtained in practice by inserting experimental copolymerization rates into Eq. (7.52) are frequently greater than unity. (For styrene-methylmethacrylate, for... 

P8 M is not the only polymer forming the isotropic smectic phase. To date, we have observed formation of that phase for a half-dozen chiral polymethacrylates and polysiloxanes. Table 5.1 summarizes the chemical structure and phase behavior of synthesized side-chain homopolymers, which carry chirally substituted side chains derived from asymmetric esters of terephthalic acid and hydroquinone. Such a structure with alternating orientation of carboxylic link groups seems to favour the formation of the IsoSm phase, whereas isomeric derivatives of p-hydroxybenzoic acid, where all carboxylic links have the same orientation, form only conventional Sm A and Sm C phases. Molar mass of all the synthesized homo- and copoly(meth)acrylates is within the range of 1 to 2-10 g mol the poiysilox-anes have the average degree of polymerization, p 35. 

An alkylimidazole derivative having a vinyl bond was synthesized 1-imidazolyl-dodecadienoylacid ester 20) The phospholipid derivative 18 or 19 was copoly-merized with 20 in the presence of / 7 to give a more advanced poly-lipid liposome/ lipid-heme (Fig. 8) where 17 was more strongly fixed into the poly-lipid liposome. 

A copolymeric derivative of the para-aramid fibres was introduced by Teijin in 1985 under the tradename Technora . This fibre is based on the copolymeric structure copoly-(paraphenylene/3,4 -oxydiphenylene terephthalamide) and is claimed to have a much higher chemical resistance than PPTA as well as increased abrasion and steam resistance, which are useful properties in many protective applications. Technora has a decomposition temperature of about 500 °C, and other properties are comparable with PPTA although its LOI value is slightly lower at 25 vol%. 

Infrared spectra are valuable in the examination of small molecular-weight intermediates, such as blocked and activated derivatives of amino acids. The stretching frequency for the urethane carbonyl (around 1700 cm" ) is distinguishable from that of the activated carbonyl group in anhydrides (over 1800 cm or in active esters (around 1800 cm ). Also, changes in ir spectra were used for monitoring transformations in polymeric supports. For instance, conversion of chloromethylated copoly-styrene-divinylbenzene to the acetoxy... 

Melt spun fibers of copoly(HBA/DHN/TPA) were obtained from Celanese Research Company for three monomer mole ratios 60/20/20, 50/25/25, and 40/30/30. These copolymers had been prepared by melt copolymerization of the three monomers (using the acetoxy derivatives of HBA and DHN) as described by Calundann [9]. Melt spun fibers of HBA-modified PET were supplied by Tennessee Eastman Company, and contained 60 and 80 mole % HBA. These had been synthesized from PET and 4-acetoxy-benzoic acid by transesterification in the melt, as described by Jackson and Kuhfuss [10]. 

Examination on a hot-stage polarized microscope, as well as SALS and DSC data let us to the conclusion, that all polymers derived from the mixture of DHBP-A and DHBP with suberyl dichloride (Series I) or sebacyl dichloride (Series II) behave as thermotropic liquid crystals. For most of them DSC scans revealed two endo-therms, which are believed to correspond to solid-to-liquid crystalline (Tm) and mesophasic-to-isotropic (Ti) transitions. In few cases, i.e. for polycimidoester derived from DHBP-A with sebacyl dichloride and the copoly-amidoesters of Series II in which DHBP-A content exceeded 40 mol%, the multiple melting endotherms were observed. Though the similar phenomena were demonstrated by several authors (11,12) their origin is still not clear. 

In this paper, we review continuous thermodynamics as applied to copolymer systems. Special attention is focused on liquid-liquid equilibria and thermodynamic stability. Equilibria in solutions of random copolymers, blends of random copolymers with homo- or copolymers, and also the high pressure phase equihbrium in the mixture of copoly(ethene vinylacetate) with its monomers are also discussed. A special examination of polydispersity effects in solutions with block copolymers is made. Thus, the paper reviews in a comprehensive way how to build up continuous thermodynamics with multivariate distribution functions and how to derive relations necessary for solving special problems. Some short remarks on possible future prospects will round up the paper. 

Choksi and Ren (2005) derived a density functional theory for diblock copoly-mer/homopolymer blends. Their numerical results were shown to capture the muMscale separation in the system (i) macrophase separation into homopolymer-and copolymer-rich macrodomains followed by (ii) microphase separation into A- and B-rich microdomains within the copolymer-rich macrodomains. They also demonstrated a result on local minimizers in one space dimension, confirming a lamellar multiscale phase separation. 

The names of copolymers, derived either from the main scheme or the alternative, can be further modified to indicate various structural features. For example, the chemical nature of end groups can be specified as a-X-)-carboxy-6ZocA-copoly(st5n ene/butadiene). 

Copoly(Styrene-bUtylene glycol). Because of the favorable properties shown by the PEG-based cross-linkers, Janda investigated other types of crosslinkers (97). Because of the tendency of PEG to complex organometalUc com-poimds and its high hydrophilicity, new t3q>es of polyst5Tene resin containing polytetrahydrofuran -st5T ene derivatives as cross-linkers were prepared to allow... 

Typical of these materials are the poly(vinyl thioethers), the poly(vinyl isocyanates), the polyfvinyl ureas) and the poly(alkyl vinyl ketones). Methyl isopropenyl ketone and certain vinylpyridine derivatives have been copoly-merised with butadiene to give special purpose rubbers. 

Liu, Y., Wang, L., and Pan, C. (1999). Synthesis of block copoly(styrene-b-p-nitrophenyl methacrylate) and its derivatives by atom transfer radical polymerization. Macromolecules, 32(25) 8301-8305. 

LeCorre D, Bras J, Dufresne A (2011) Evidence of micro- and nanoscaled particles during starch nanocrystals preparation and their isolation. Biomacromolecules 12 3039-3046 Lee KY, Tang M, Williams CK, Bismarck A (2012a) Carbohydrate derived copoly(lactide) as the compatibilizer for bacterial cellulose reinforced polylactide nanocomposites. Compos Sci Technol 72 1646-1650... 

---