PDMAEMA

New drug delivery systems are of great scientific and commercial interest. Amphiphilic networks composed of about 50/50 hydrophobic PIB and hydrophilic poly(2-(-dimethylamino)ethyl methacrylate) (DMAEMA) polymer segments were found to be biocompatible and to a large extent avascular (7). These PHM-PDMAEMA networks (i, in line with propositions of Weber and Stadler (2), and Sperling (J), denotes PDMAEMA chains linked by PIB chains) gave pH dependent... 

Monofunctional 2-bromo-2-methylpropionic acid 4-methoxyphenyl ester and difunctional l,4-(2/-bromo-2/-methyl-propionate)benzene initiators, given in Scheme 26, were employed for the polymerization of n-BuMA followed by the addition of DMAEMA, thus leading to the formation of PnBuMA-fo-PDMAEMA block and PDMAEMA-b-PnBuMA-h-PDMAEMA tri-... 

GTP was employed for the synthesis of block copolymers with the first block PDMAEMA and the second PDEAEMA, poly[2-(diisopropylamino)e-thyl methacrylate], PDIPAEMA or poly[2-(N-morpholino)ethyl methacrylate], PM EM A (Scheme 33) [87]. The reactions took place under an inert atmosphere in THF at room temperature with l-methoxy-l-trimethylsiloxy-2-methyl-1-propane, MTS, as the initiator and tetra-n-butyl ammonium bibenzoate, TBABB, as the catalyst. Little or no homopolymer contamination was evidenced by SEC analysis. Copolymers in high yields with controlled molecular weights and narrow molecular weight distributions were obtained in all cases. The micellar properties of these materials were studied in aqueous solutions. 

ABC, ACB, and BAC triblock terpolymers, where A is PMMA, B is PDMAEMA, and C is poly[hexa(ethylene glycol)methacrylate], PHEGMA, were synthesized via GTP and sequential monomer addition [89]. The polymerizations were conducted in THF using MTS and TBABB as the initiator... 

The triblock terpolymer polypropylene oxide)-h-poly[2-(dimethylami-no)ethyl methacrylate]-b-poly[oligo(ethylene glycol) methacrylate], PPO-fc-PDMAEMA-fc-POEGMA, was prepared using the PPO macroinitiator followed by the addition of CuCl, HMTETA, and DMAEMA for the polymerization of the second block and finally OEGMA for the synthesis of the final product (Scheme 54) [128]. 

Hydrogels that have the ability to respond to pH changes have been studied extensively over the years. These gels typically contain side ioni-zable side groups such as carboxylic acids or amine groups (Oppermann, 1992 Scranton et al., 1995). The most commonly studied ionic polymers include polyacrlyamide (PAAm), poly(acrylic acid) (PAA), poly(metha-crylic acid) (PMAA), poly (diethylaminoethyl methacrylate) (PDEAEMA), and poly(dimethylaminoethyl methacrylate) (PDMAEMA). 

Selective betainization of the PDMAEMA block of PDMAEMA-PDEAEMA, PDMAEMA-PDPAEMA, and PDMAEMA-PMEMA copolymers by propane-sultone resulted in thermosensitive systems, as reported by Armes and coworkers [160,188]. 

Early examples of micelles formed by BAC triblock copolymers have been reported by Patrickios and coworkers, who studied the formation of micelles from polyampholytic PDMAEMA-PMMA-PMAA and PDMAEMA-poly(2-phenylethylmethacrylate)-PMAA copolymers as a function of pH [285-287]. 

IPEC-containing micelles based on double-hydrophilic cationic block copolymers, such as PLL [303-306], PEI [307], or PDMAEMA [308] in combination with PEO, have been examined for the complexation of oligonucleotides in order to provide new pharmaceutical forms for gene therapy [309]. 

Fig. 11 Chemical formulas of poly(acryl amide) (PAAm), poly(methyl methacrylate) (PMMA), poly(2-hydroxyethyl methacrylate) (PHEMA), poly(t-butyl acrylate) (PtBA), and poly(acrylic acid) (PAA), and poly(dimethyl aminoethyl methacrylate) (PDMAEMA)...

While the bulk behavior of polyampholytes has been investigated for some time now, studies of interfacial performance of polyampholytes are still in their infancy. There are several reasons for the limited amount of experimental work the major one being the rather complex behavior of polyampholytes at interfaces. This complexity stems from a large array of system parameters governing the interaction between the polymer and the substrate. Nearly all interfacial studies on polyampholytes reported to-date involved their adsorption on solid interfaces. For example, Jerome and Stamm and coworkers studied the adsorption of poly(methacryhc acid)-block-poly(dimethyl aminoethyl methacrylate) (PMAA-fc-PDMAEMA) from aqueous solution on sihcon substrates [102,103]. The researchers found that the amount of PMAA-fo-PDMAEMA adsorbed at the solution/substrate interface depended on the solution pH. Specifically, the adsorption increased... 

Fig. 31 Dry thicknesses of PDMAEMA ( ), PDMAEMA-fc-PAA ( ), and PDMAEMA-fc-PtBA (A) as a function of the position on the silica substrate. The symbols , , , and mark the loci on the specimen where the wet thickness measurement was carried out (cf. Pigs. 32-34)...

Fig. 32 Dependence of cosine of A and tangent of where A and are ellipsometric angles related to the change of amplitude and phase shift of the incident polarized light, on the wavelength of the incident polarized light collected from PDMAEMA- -PAA brushes immersed in solutions of a constant ionic strength 0.001 M) and pH ranging from 3.52 to 9.50. The data in figures a and b (c and d) have been collected at the position 1 (4). For clarity the data for cos(A) and tan(V ) collected at pH > 3.53 were shifted vertically by - 0.2 relative to each previous set...

Fig. 34 Schematics illustrating the suggested conformations of PDMAEMA-fc-PAA brushes of a constant composition grafted on a solid substrate as a function of the solution pH (cf. Figs. 31 and 33)...

Fig. 36 Dry thickness of polyfdimethyl aminoethyl methacrylate) (PDMAEMA) on an orthogonal PDMAEMA gradient grafted on a silica substrate. Thickness was measured in a grid of 5 mm x 5 mm on the substrate. (Reproduced with permission from [117])...

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