Poly ethyl methacrylate PDMAEMA

The first diblock copolymer brushes synthesized in our group were made by a combination of carbocationic polymerization and ATRP (Scheme 1) [46]. Zhao and co-workers [47] synthesized diblock copolymer brushes consisting of a tethered chlorine-terminated PS block, produced using carbocationic polymerization, on top of which was added a block of either PMMA, poly(methyl acrylate) (PMA) or poly((Ar,M -dimethylamino)ethyl methacrylate) (PDMAEMA), synthesized using ATRP. The thickness of the outer poly(meth)acrylate block was controlled by adding varying amounts of free initiator to the ATRP media. It has been reported that the addition of free initiator is required to provide a sufficiently high concentration of deactivator, which is necessary for controlled polymerizations from the sur-... 

There are only a few cases in which polyelectrolyte stars have been prepared by the arm-first strategy. Qiao et al. prepared pH responsive poly(acrylic acid) stars by the MI method using atom transfer radical polymerization (ATRP), which was used to form layer-by-layer (LBL) polyelectrolyte multilayers with linear cationic polyelectrolytes [54], Matyjaszewski et al. obtained cationic poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) stars and anionic PAA stars also using the MI method, which formed all-star LBL layers [55], Ishizu et al. obtained... 

Potentiometric [50] and viscometric [151] measurements on poly[2-(dimethylamino) ethyl methacrylate] (PDMAEMA) indicate that the polyelectrolyte undergoes a... 

Poly(2-dimethylamino)ethyl methacrylate (pDMAEMA) is a water-soluble cationic pol3maer that contains tertiary amines and shows the proton sponge effect to some extent due to pKa=7.5. Approximately 50% of the amines are protonated at pH 7.2 impl3rmg that the other 50% participate in buffering. The absence of primary and secondary amines indicates that pDMAEMA binds relatively loosely to pDNA compared to polycations such as PEI-25K and other high MW PEI. It has been shown to condense pDNA into 150-180 nm size particles and mediate transfection in different cell types. However, complexes with pDMAEMA are not very stable in physiological salt and serum and since they do not possess attributes other than DNA condensation and modest endoso-mal buffering, attempts have been made to modify them (71)... 

Using an original approach, Zhang and coworkers recently reported the synthesis of PMMA latex particles stabilized by MMT platelets tethered with poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) brushes (Fig. 33) [290]. The PDMAEMA polyelectrolyte brush was synthesized by atom transfer radical polymerization using a cationic initiator previously introduced in the clay galleries. The PDMAEMA-functionaUzed clay platelets were further used to stabilize the emulsion polymerization of MMA initiated by the remaining free radical initiator present on the clay surface. 

Polyamidoamine (PAMAM), polyethylenimine (PEI) and poly[2-(dimethyl-amino)ethyl methacrylate] (PDMAEMA) are widely used as non-viral vectors because of their ability to condense DNA and to form complexes (polyplexes) for more efficient uptake through endoc)d osis. However, it is difficult for these cationic polymers to enter the brain tissue by crossing the BBB. A list of synthetic cationic polymers enabling in vivo and ex vivo transfection to the CNS is provided in Table 17.4. 

Huang and coworkers [437] reported preparation of a series of well-defined amphiphilic block copolymers containing conjugated poly(fluorene) (PF) block and coil like poly(2-(dimethylamino) ethyl methacrylate) (PDMAEMA). The block copolymers were synthesized through ATRP. The reactions were initiated by a 2-bromoisobutyrate end-capped macroinitiator using CuCl/ 1,1,4,7,10,10-hexamethyltriethylenetetramine as the catalyst. 

All of the above features make silica colloidal crystals ideal candidates for highly selective responsive nanoporous membranes. However, until 2005, there were no publications describing transport through surface-modified colloidal membranes. In 2005, Zharov group introduced, for the first time, the concept of permselective colloidal nanoporous membranes by describing pH-responsive amine-modified colloidal membranes with controlled transport of positively charged species [26]. Later, they reported a detailed study of transport through amine-modified colloidal membranes [27], as well as membranes modified with sulfonic acids [28,29], Methods to modify the colloidal nanopores with polymers were developed [30], which allowed us to introduce temperature-responsive poly(A-isopropylacrylamide) (PNIPAAM) [31], pH- and ion-responsive poly(2-(dimethylamino)ethyl methacrylate), PDMAEMA [32], and pH- and temperature-responsive poly(L-alanine) [33], and to study the molecular transport in these polymer-modified nanoporous coUoidal membranes as a function of the environmental conditions. In this chapter we summarize these results. 

Controlled structure polymeric betaines were reported for the first time only recently (286). The first examples were those prepared from the post-polymerization modification of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA), and its block copolymers, which had been prepared imder GTP conditions (286,287). Initial reports detailed the modification of hydrophilic-hydrophobic block copolymers, but this was subsequently extended to the selective modification of diamino hydrophilic-hydrophilic block copolymers (276). 

Poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) is usually used as weak polyelectrolyte for gene delivery and has the additional property of being temperature sensitive [140, 141]. The study by Stolnik and coworkers on PDMAEMA (Fig. 7a) emphasized the condensation behavior of PDMAEMA as a function of pH [102]. As can be intuitively understood, the ionization of PDMAEMA increases from pH 8 (only 24% ionization) to pH 4 (polycation nearly completely ionized), therefore the binding of PDMAEMA with DNA is tighter (EtBr displacement assay) at lower pH, which is counterproductive when it comes to release of the genetic material. But, this effect is balanced by its buffering capacity via the tertiary amine groups, which is favorable for endosomal escape. 

Fig. 1 Plots of 0 versus pH for various polyelectrolyte systems (1) poly(acrylic acid) (PAA) -poly(L-lysine) (2) PAA - poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) (3) poly (L-glutamlc acid) - PDMAEMA (4) PAA - poly(A-ethyl-4-vinylpyridinium bromide) (P4VPQ) (5) poly(4-vinylpyridine) - poly(sodium styrene sulfonate) (PSSNa) (6) PDMAEMA - PSSNa. Reprinted from [27] with kind permission from MAIK Nauka/Interperiodica Copyright 1999...

So what is known about the kinetics of C3M association and dissociation In 1998, Cohen Stuart and co-workers first studied the formation kinetics of H-C3Ms for poly((dimethylamino)ethyl methacrylate)-co-poly-(glyceryl methacrylate) (PDMAEMA -co-PGMA) and poly(acrylic acid) (PAA) [17]. A strong excess... 

The group of Hennink et aL [69-72] synthesized and evaluated poly(2-(dimethylamino)ethyl methacrylate) pDMAEMA for gene transfer. The polymer forms positively charged DNA polyplexes which can be used successfully for in vitro transfection of different cell lines, including COS-7 and OVCAR-3... 

Zhang et al. controlled the size of nanoparticles by exploiting the pH and temperature responsiveness ofa poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) brush [68]. Briefly, a PDMAEMA bmsh was synthesized onto a polystyrene latex nanoparticle via atom transfer radical polymerization (ATRP). Dynamic light-scattering events indicated that pH changes led to temperature changes in solution, which resulted in an alteration in particle size. This approach could be useful in enzyme immobilization or protein separation. 

In a previous study, our group synthesized a new temperature and pH-sensitive poly(2-(dimethylamino) ethylmethacrylate-fe-vinylcaprolactam-fc-(2-(dimethylamino) ethyl methacrylate)), PDMAEMA- i-PVCL-fc-PDMAEMA, triblock copolymer by RAFT polymerization. PDMAEMA is dual sensitive (pH and temperature) and its LCST was around 50 °C, while PVCL is a thermo-responsive polymer and its LCST was around 32 °C. By modifying the structure and adjusting the composition of these polymers it is possible reduce the LSCT and pK values in order to ensure compatibility with physiological temperature and pH (see Table 9.1, Triblock 1). The results showed that these polymers can self-assemble into micelles in different environments [60]. 

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