Poly- , chemical structure

Depending on the chemical structure of the MAI, a suitable solvent is sometimes needed to get a homogenous state of reaction mixture. Even if using the same combination of comonomers, for example, to prepare PMMA-b-poly(butyl acrylate) (PBA), the selection of the using order of comonomers for the first step or second step would affect the solvent selections, since PMMA is not easily soluble to BA monomer, while PBA is soluble to MM A monomer [28]. 

This article, while not being intended to provide a full account of poly(arylene)s, emphasises the synthetic aspects. The synthesis of conjugated oligomers and polymers is, however, always part of an interdisciplinaiy approach with their active physical function being a key concern. In that sense the research being reviewed above concentrates on physical properties rather than playing with exotic chemical structures. 

Two Hell UPS spectra of poly(3-hexylthiophene), or P3HT, compared with the DOVS derived from VEH band structure calculations 83], arc shown in Figure 5-14. The general chemical structure of poIy(3-a ky thiophcne) is sketched in Figure 5-4. The two UPS spectra, were recorded at two different temperatures, +190°C and -60 "C, respectively, and the DOVS was derived from VEH calculations on a planar conformation of P3HT. Compared to unsubslitutcd polythio-phene, the main influence in the UPS spectra due to the presence of the hexyl... 

Figure 10-6. Chemical structure of the ladder-type poly(/xi/u-pheny-Icne). X represents u methyl-group and R and R are /i-hcxyl aud 1,4-dccylphcnyl, respectively.

Figure 11-1. Chemical structure of poly(pura-phenylene vinylene) (PPV) and schematic polymer LED device structure.

In Figure 8-1 we show the chemical structure of m-LPPP. The increase in conjugation and the reduction of geometrical defects was the main motivation to incorporate a poly(/ -phenylene)(PPP) backbone into a ladder polymer structure [21]. Due to the side groups attached to the PPP main chain excellent solubility in nonpolar solvents is achieved. This is the prerequisite for producing polymer films of high optical quality. A detailed presentation of the synthesis, sample preparation,... 

See also PBT degradation structure and properties of, 44-46 synthesis of, 106, 191 Polycaprolactam (PCA), 530, 541 Poly(e-caprolactone) (CAPA, PCL), 28, 42, 86. See also PCL degradation OH-terminated, 98-99 Polycaprolactones, 213 Poly(carbo[dimethyl]silane)s, 450, 451 Polycarbonate glycols, 207 Polycarbonate-polysulfone block copolymer, 360 Polycarbonates, 213 chemical structure of, 5 Polycarbosilanes, 450-456 Poly(chlorocarbosilanes), 454 Polycondensations, 57, 100 Poly(l,4-cyclohexylenedimethylene terephthalate) (PCT), 25 Polydimethyl siloxanes, 4 Poly(dioxanone) (PDO), 27 Poly (4,4 -dipheny lpheny lpho sphine oxide) (PAPO), 347 Polydispersity, 57 Polydispersity index, 444 Poly(D-lactic acid) (PDLA), 41 Poly(DL-lactic acid) (PDLLA), 42 Polyester amides, 18 Polyester-based networks, 58-60 Polyester carbonates, 18 Polyester-ether block copolymers, 20 Polyester-ethers, 26... 

Molecular structural changes in polyphosphazenes are achieved mainly by macromolecular substitution reactions rather than by variations in monomer types or monomer ratios (1-4). The method makes use of a reactive macromolecular intermediate, poly(dichlorophosphazene) structure (3), that allows the facile replacement of chloro side groups by reactions of this macromolecule with a wide range of chemical reagents. The overall pathway is summarized in Scheme I. 

FIG. 7 Chemical structures of fluorocarbon ammonium amphiphile 1 and poly(styrene sulfonate) (PSS). 

Our interest in the past few years has been on biodegradable polymers. We have been evaluating the potential of poly(phosphoesters) as degradable biomaterials (4).We were attracted to this class of polymers because the phosphoester bond in the backbone is cleavable under physiological conditions, the presence of the P-O-C group would facilitate fabrication, and the versatile chemical structure affords a wide... 

Table I. The chemical structures used in the synthesis of poly(phosphoester-urethanes)...

The in vitro degradation profiles of several TDI poly(phosphoester-ure thanes) are shown in Figure 2. It is not possible from this study to correlate the decomposition kinetics with the chemical structure, except for the fact that biodegradability is demonstrated. The in vitro release of 5-FU from PPU-7 is shown in Figure 3. After an initial burst, a reasonably steady and sustained release followed. The UV spectrum of the released 5-FU was identical to that of pure 5-FU, suggesting the chemical integrity of the drug. 

F Koosha, RH Muller, SS Davis, MC Davies. The surface chemical structure of poly (/J-hydroxybutyrate) microparticles produced by solvent evaporation process. J Control Rel 9 149, 1989. 

Figure 10.2 Chemical structures of po y(methyl methacrylate) and poly(vmylidene fluoride)...

Likewise, poly (methyl methacrylate) and polyfvinylidene fluoride), the chemical structures of which are shown in Fig. 10.2, make a miscible blend because of the strong specific interactions between the oxygen atoms on the methacrylate and the fluoride group in the vinylidene fluoride group. 

Similar molecular weight poly(DMA-co-EPl), 1750 daltons, ca. 13 repeat units, and poly(TMDAB-co-DCB), 1500 daltons, ca. 11 repeat units were compared. The two condensation polymers appeared to be about equally effective in preventing the swelling of Wyoming bento-nite. Any small differences are probably due to repeat unit chemical structure differences rather than the small variations in polymer molecular weight. The presence of the hydroxyl group and the smaller N - N distance in poly(DMA-co-EPl) could affect polymer conforma-tion in solution, geometry of the polymer - clay complex, and surface properties of the polymer - clay complex as compared to poly(TMDAB-co-DCB). 

Figure 9 Chemical structures of poly(acrylate)s and numberings of carbons.

The polyesters synthesized by microorganisms were first investigated by Lemoigne, who isolated the reserve polymers in Bacillus megaterium in 1925 and identified the polymer to be poly(3-hydroxybutyrate), poly(3HB) [1]. The chemical structure of poly(3HB) is shown in Fig. 1. 

Since the chemical structure and monomer composition of a specific polymer are the most important factors in determining the polymer s physical and material properties, a short recapitulation of typical representatives of microbially synthesized poly(hydroxyalkanoates) is presented in this section. A more detailed overview on this issue is available from References [19-21], but is not within our scope here. The monomer composition of PHAs depends on the nature of the carbon source and the microorganisms used. This way, numerous monomers have been introduced into PH A chains [3-9]. PHAs have been divided roughly into two classes [19]. 

First, the short chain length PHAs, poly(HASCL), are composed of monomeric units containing up to 5 carbon atoms. The most well-known representatives are poly(3-hydroxybutyrate) (PHB), and its copolymers with hydroxyvalerate. Of all the PHAs, PHB is by far the most commonly encountered in nature [18]. It is the simplest PHA with respect to chemical structure, having a methylene (-CH3) group as the pendent R-unit in Fig. 1. Owing to its enzymatic synthesis, PHB has an exceptional stereochemical regularity. The chains are linear and the chiral centers all are in the R-stereochemical conformation, which implies that this polymer is completely isotactic. 

Fig. i. Chemical structure of poly(hydroxyalkanoate) repeating unit... 

Fig. 4 Chemical structures of synthetic and naturally occurring poly(amino acidjs...

Fig. 12 (a) Chemical structure of poly(sarcosine)-b-poly(y-methyl L-glutamate) copolymer. 

Fig. 1 Chemical structure of water-soluble poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate-co-p-vinylphenylboronic acid (PMBV)...

An exhaustive theoretical characterization of the chemical structure of poly-disperse block copolymers suggests knowledge of the distributions of ... 

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