Amine-based polymers

Furthermore, the chemical structure of networks are changed by thermal oxidation reactions 17,23,24F These are rather important for epoxy networks with aliphatic amines since they usually take place in the presence of air at T 130 °C. In aromatic amine-based polymers this kind of reaction becomes important at T > 220° 240 °C 17-23>. The only exception are polymers with a large excess of epoxy groups in the initial mixture. For example, the polymer with P = 0.4 23) starts loosing its weight at 160 °C17 23,24). All polymers considered in this paper are prepared from mixtures with 0.6 P 1.6. Cure and post-cure treatment temperatures are below 190 °C. This means we may not consider thermal oxidation processes in our structural analysis of the networks. 

Another approach that has been proven to be successful is the incorporation of reactive moieties in polymers to selectively increase the affinity of one penetrant over the others, the so-called facilitated transport mechanisms. In this case a chemical contribution is added to the physical flux in view of a chemical reaction of the target penetrant with the reactive moieties present in the membrane matrix, whereas aU of the other components are able to permeate only because of the physical mechanism. This approach allows the simultaneous achievement of high flux for the target compound and large selectivity, moving perpendicularly to the membrane upper bound. A typical example is the use of amine-based polymers as a membrane matrix under humid conditions because water is needed to catalyze the chemical reaction [37,38]. The carrier can be chemically bonded to the membrane matrix [39] or low-molecular-weight molecules able to freely move in the swollen matrix [40]. Nevertheless, this approach has also been used for the recovery of pharmaceutical chemicals, such as Cephalexin [41], as well as metal ions from waste water [42]. 

Antistatic polystyrenes have been developed in terms of additives or coatings to minimise primarily dust collecting problems in storage (see Antistatic agents). Large Hsts of commercial antistatic additives have been pubhshed (41). For styrene-based polymers, alkyl and/or aryl amines, amides, quaternary ammonium compounds, anionics, etc, are all used. 

A new family of peroxide-cured dipolymers was introduced in 1991. The peroxide cure provides copolymers that cure faster and exhibit good compression set properties without a postcure. The removal of the cure-site has also made the polymer less susceptible to attack from amine-based additives. By varying the methyl acrylate level in the dipolymer, two offerings in this family have been synthesized, VAMAC D and its more oil-resistant... 

The literature3 contains some limited work on decaborane-based polymer systems. Typically, most utilize the Lewis acid/base reaction between decaborane (Lewis acid, B10H12) and amines and phosphines (Lewis bases, L) resulting in the formation of complexes (see scheme 2) having the general formulas B10H12L2. For example, the... 

Amino-substituted (Mannich base) polymers can be prepared by reacting amide-containing polymers with formaldehyde and a suitable amine. Sugiyama and Kamogawa (16) treated PAM in aqueous solution with excess paraformaldehyde (50°C, lh) followed by excess dimethylamine (50°C, lh). This procedure gave 68% conversion to amine. Schiller and Suen (9) used a similar procedure with monomeric formaldehyde and various amines, but with excess PAM. Muller et al. (17) prepared monomeric amines from... 

Quenching polystyryllithium and polybutadienyllithiums with A-benzylidenemethyl-amine (PhCH=NMe) in benzene solution leads to amine-functionalized polymers (equation 103), that can be characterized by SEC, TLC, acid-base titration and H and C NMR spectroscopies. The end groups are monomeric. Gradual addition of Et20 reduces the yields. This is attributed to increased reactivity of the alkyllithium residues in the polymer, bringing about a concurrent metallation reaction of the imine reagent (e.g. equation 101) . 

On the other hand, Lucht showed the cross-coupling polycondensation of primary phosphine 172 with arylene dihalide to give polymer 173. (Equation (83)) The reaction takes place with a Pd(PPh3)4 catalyst in the presence of a tertiary amine base. In particular, the reaction of 1,4-diiodobenzene with isobutylphosphine proceeds at 70 °C in the presence of triethylamine to give the corresponding polymer 173a (R = Bu) in 83% yield (d/n= 1700, PDI = 1.3) 173b (d/ = 5000, PDI = 1.6). 

Copolymers of methacrylic add and ethylene termed as ethylene ionomers have been used as the base polymer for binding alkali, alkaline earth and transition metal ions. Organic amines such as n-hexylamine, hexamethylene tetraamine, 2,2,6,6-tetramethyM-hydroxy piperazine, ethylene diamine and polymeric diamines such as silicone diamine, polyether diamine and polymeric diamines such as silicone diamine, polyether diamine and polyamide oligomers considerably enhance the complex formation characteristics of Zn(II) ethylene ionomers thereby enhancing the physico-chemical properties [13]. 

Research into chemically modified electrodes has led to a number of new ways to build chemical selectivity into films that can be coated onto electrode surfaces. Perhaps the simplest example is the use of the polymer Nafion (see Table 13.2) to make selective electrodes for basic research in neurophysiology [88]. Starting with the pioneering investigations by Ralph Adams, electrochemists have become interested in the electrochemical detection of a class of amine-based neurotransmitters in living organisms. The quintessential example of this class of neurotransmitters is the molecule dopamine, which can be electrochemically oxidized via the following redox reaction ... 

Just as proteins are polymers made of amino acid units, nucleic acids are polymers made up of nucleotide units linked together to form a long chain. Each nucleotide is composed of a nucleoside plus phosphoric acid, H3PO4, and each nucleoside is composed of an aldopentose sugar plus an amine base. 

Liang, Z.-M., Yin, J., and Xu, H. J. Polyimide/montmorillonite nanocomposites based on thermally stable, rigid-rod aromatic amine modifies, Polymer (2003), 44, 1391-1399. 

The rate of reversion, or hydrolytic instability, depends on the chemical structure of the base polymer, its degree of crosslinking, and the permeability of the adhesive or sealant. Certain chemical linkages such as ester, urethane, amide, and urea can be hydrolyzed. The rate of attack is fastest for ester-based linkages. Ester linkages are present in certain types of polyurethanes and anhydride cured epoxies. Generally, amine cured epoxies offer better hydrolytic stability than anhydride cured types. 

Proteins are mostly separated by CZE. Strong interactions between the analyte molecules and the capillary wall that are predominately electrostatic in nature have a strong influence on separation efficiency. By the use of buffer additives like amines or the use of dynamically or permanently coated capillaries, highly efficient separation of proteins in CZE is achievable. Here, the native proteins with their tertiary structure are separated. Denatured proteins as SDS complexes can be separated in gels. Advantageous are polysaccharide-based polymers, because they permit UV detection at low wavelength (214 nm), impossible with acrylamide-based gels. A separation of SDS-denatured protein standards in a dextran gel is shown in Fig. 7. 

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