Types of Cationic Polymer

Linear cationic polymers represent a single chain of cationic copolymers of well-defined molecular weights. These polymers as well as their analogues of different shapes can be subdivided into various categories based upon their molecular weights, compositions and co-monomer types. 

3 Architecture. The advent of LRP has allowed the synthesis of cationic copolymers of well-defined architectures, hence allowing a careful analysis of the structure-activity relationship of these polymers. Synthetic linear cationic glycopolymers of statistical, block and block-statistical architectures were prepared by RAFT polymerization and studied for their gene expression profiles, as a function of molecular weight, carbohydrate content as well as architecture. The copolymers of 30-40 kDa and of 

Star with N-based Core (S-N) Star with Protonated N based Core (S-NH) ATItP Prutortatien 

3 Enzymatically Degradable Polymers. The introduction of chit-osan in the cationic polymer backbone has been used as a way to obtain enzymatically degradable polymers. The chitosan backbone was copolymerized with DMEMA side-chains to obtain an enzymatically degradable vector with improved endosomal escape properties. 

4 Thermoresponsive Polymers. Poly[(ethylene glycol) methacrylate] (PEGMA) and poly(iV-isopropylacrylamide) (PNIPAam) are well-studied polymers for imparting thermoresponsive properties to cationic vectors. These polymers undergo a phase transition (from random coil to globular form) at a lower critical solution temperature (LCST) near the 

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The vapor-phase acylation of pyrrole was carried out over zeolite catalysts such as HZSM-5(19.7), HZSM-5(30), HZSM-5(280), HY, and cation-promoted modified zeolites like CeHZSM-5(30), LaHZSM-5(30), and CeHY, in a fixed-bed reactor at atmospheric pressure using acetic anhydride as an acylating agent <1998CAL95>. The catalytic activity of the zeolite catalysts was dependent on the reaction temperature and the type of cation polymer used in the modification of the zeolite surface. The acylation was found to be more active on Br0nsted acidic sites available over zeolite systems. The yield of l-(l//-pyrrol-2-yl)-l-ethanone 376 with respect to the conversion of pyrrole on HZSM-5(280) at 250 °C was 75.5% (Equation 87). 

The retention of the AKD, the breaking of the dispersion, and subsequent sizing development, will be influenced by the amount and type of cationic polymer/starch used, either in the dispersion, or added separately to the stock, and the amount of anionic trash present in the furnish. Good retention of the AKD is essential for efficient sizing, but unlike ASA, there is considerable evidence that the AKD dispersion, if not retained in the first pass, is still in an active form whilst in the white water, and can still provide sizing if retained on second, third and subsequent passes round the short circulation loop, provided that the conditions are not too harsh (high temperature/high shear). 

An example of an early and very detailed investigation of such a dual system is the work of Moore [13], in which different types of cationic polymers were combined with hydrolyzed polyacrylamides at various alumina concentrations. In contrast to other workers, Moore studied the charge relationship of the various charged species. He discovered that a combination of cationic and anionic polymers can give very high levels of retention with high shear resistance only in the case of a proper balance of charges and concentrations. 

Various types of cationic polymers have been tested for gene transfection into vascular or cardiac cells, including linear or branched PEI, polyamidoamine dendrimer, PLL, and poly(j3-amino esters). The positively charged polymer-DNA complexes enter the cytoplasm by binding... 

The chemical composihons of the zeolites such as Si/Al ratio and the type of cation can significantly affect the performance of the zeolite/polymer mixed-matrix membranes. MiUer and coworkers discovered that low silica-to-alumina molar ratio non-zeolitic smaU-pore molecular sieves could be properly dispersed within a continuous polymer phase to form a mixed-matrix membrane without defects. The resulting mixed-matrix membranes exhibited more than 10% increase in selectivity relative to the corresponding pure polymer membranes for CO2/CH4, O2/N2 and CO2/N2 separations [48]. Recently, Li and coworkers proposed a new ion exchange treatment approach to change the physical and chemical adsorption properties of the penetrants in the zeolites that are used as the dispersed phase in the mixed-matrix membranes [56]. It was demonstrated that mixed-matrix membranes prepared from the AgA or CuA zeolite and polyethersulfone showed increased CO2/CH4 selectivity compared to the neat polyethersulfone membrane. They proposed that the selectivity enhancement is due to the reversible reaction between CO2 and the noble metal ions in zeolite A and the formation of a 7i-bonded complex. 

ZIL monomers, having both cation and anion in the same monomer unit, were prepared in order to give different types of ampholyte polymers. Figure 30.4 shows the structure of the monomers used here [6]. Four different monomers were synthesized to study the relation between structure and such properties as ionic conductivity and Tg. 

More recent efforts investigating the kinetics and mechanism of cationic polymerization of oxazolines are aimed at the preparation of various types of functional polymers as described in a recent review [181] (cf., Section IV.D). One of the examples is the development of efficient di- and tetrafunctional initiators of oxazolines polymerization, allylic or benzylic dihalides and allylic tetrahalides [182], e.g. ... 

Another type of cationic graftir involves the initiation from a halogenated polymer submitted to ionising radiation. Chapiro has summarised the little work done in this field and reported some work of his own on the grafting of styrene and isobu-... 

Penczek discussed at Kyoto the interesting problem of carbenium ion — onium ion equilibria and summariKd data and concepts elaborated recently in his laboratory. The aspect most relevant here has to do with the cationic polymerisation of rr — and n-donor monomers in which the active carbenium ions can equilibrate with the corre onding onium ions both intramolecularly (isomerisation of the active species) and intermolrani-larly (reaction with the n-donor atom of a polymer chain). Owing to the marked differences in stability and reactivity of the two types of cations, these interactions would of course bring about important kinetic complications in sterns involvii such monomers as vinyl ethers. 

Non viral gene delivery still suffers from limited in vivo applications due to a poor vector efficacy to deliver the gene at the target. Works on DNA delivery involve different types of cationic lipids (1, 2) or polymers (3) and degradable cationic lipid/DNA complexes (4, 5) or polymer/DNA complexes (6). 

F. D Alelio, of General Electric Co., prepared the first styrene-divinyl benzene polymers (U.S. Patents 2,340,110 and 2,340,111). These allowed various porosities of material to be prepared and provided a backbone for various types of cation and anion exchange groups to be added. (See the reaction on p. 271.)... 

Conditioning agents for shampoos are varied and may generally be classified as lipid-type, soap-type or salts of carboxylic acids, cationic-type including cationic polymers, or silicone-type including dimethicone or... 

Starch adsorption decreases with increasing specific conductivity and is sensitive to the type of salt cation. The bivalent cations Ca " and Mg " appear to be ten times as effective as Na" in suppressing the adsorption of cationic polymers. 

The macrocyles formed depend on the overall proportions of 1 and 2, the diamine chain length and the type of cation used as the template. Of importance is the fact that the imine formation is a reversible reaction. Expressed in the DCC sense, one can say that all products, the macrocycies and the nonrepresented oligomers and polymers, are in constant equilibrium, and that all the species represented in Fig. 22 constitute a virtual combinatorial library (VCL). From this library, the high proportion of a specific macrocycle can be obtained by the use of the appropriate conditions (type of metal template, relative proportion of reactants). 

Cationic polymerization [91, 92] is one of the most fundamental methods of synthesizing polymers. Although there are several types of cationic polymerization, the most important is cationic polymerization of vinyl monomers having a cation stabilizing group (Y) (Scheme 1). 

In the concept of water soluble ABC block copolymers one has also to mention a huge amount of work that has been presented on the synthesis and solution behavior of copolymers with two hydrophilic blocks and one hydrophobic. However, the presence of a permanently hydrophobic block in this type of block polymers makes difficult their categorization as DHBCs. The synthesis of ABC triblock terpolymers with at least two hydrophilic blocks has been realized via a number of polymerization methodologies, like GTP and cationic polymerization, and has been studied in detail [42,43,44,45,46,47,48,49]. In most of the cases, the terpolymers were based on suitably functionalized methacrylate monomers and have been produced by the sequential monomer addition method. 

This chapter describes the synthesis of a variety of cationic vectors hy ATRP and RAFT polymerization approaches. Owing to the facile synthesis of cationic polymers, libraries of cationic polymers of different types are produced and are evaluated for their gene expression profiles. As discussed above. 

The cytotoxicity of cationic polymers is seen as a major limiting factor in their success as drug or gene delivery vectors. Mechanisms of cytotoxicity caused by polycations is not yet fully understood however, mechanisms are thought to be influenced by different properties of the polymers, such as (i) MW, (ii) charge density and type of the cationic functionalities, (iii) structure and sequence, such as block, random, linear and branched, and finally (iv) conformational flexibility. ... 

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