Poly ethyl methacrylate block copolymers

We shall examine the range of stability of the ordered structures of copolymers containing an amorphous polystyrene, polybutadiene or poly(ethyl methacrylate) block and acrystallizable polyethylene oxide) (PEO) or poly(e-caprolactone) (PCL) crystallizable block and the factors that determine the existence and the geometrical parameters of such periodic structures. 

Wakebayashi D, Nishiyama N, Itaka K, Miyata K, Yamasaki Y, Harada A, Koyama H, Nagasaki Y, Kataoka K, Harada A (2004) Polyion complex micelles of pDNA with acetal-poly(ethylene glycol)-poly(2-(dimethylamino)ethyl methacrylate) block copolymer as the gene carrier system physicochemical properties of micelles relevant to gene transfection efficacy. Biomacromolecules 5 2128-2136... 

Tian, Z.C., Liu, X., Chen, C., Allcock, H.R. Synthesis and micellar behavior of novel amphiphilic poly bis(trifluoroethoxy)phosphazene -co-poly (dimethylamino)ethyl methacrylate block copolymers. Macromolecules 45(5), 2502-2508 (2012). doi 10.1021/ ma300139z... 

Poly[2-(dimethylamino)ethyl methacrylate-block- methyl methacrylate] copolymer, 20 485... 

On the contrary, copolymers polystyrene-poly(ethylene oxide) (SEO), poly-butadiene-poly(ethylene oxide) (BEO), poly(ethyl methacrylate)-poly(ethylene oxide) (EMAEO) and polystyrene-poly(e-coprolactone)(SCL) exhibit well organized periodic structures. Copolymers SEO261-266), BEO267-270) and SCL27 ) have been studied in the dry state and in a preferential solvent for each type of block, while copolymers EMAEO have only been studied in the dry state272-274). 

Figure 15 Schematic representation of the different morphologies obtained from poly(2-(dimethylamino)ethyl methacrylate)-f>-poly(glutamic acid) block copolymers at different pH and temperature. (Reproduced from Ref. 60. American Chemical Society, 2010.)...

Pan, Q., et al. (1999). Synthesis and characterization of block-graft copolymers composed of poly(styrene-b-ethylene-co-propylene) and poly(ethyl methacrylate) by atom transfer radical pol5merization. J. Polym. ScL, Part A Polym. Chem., 57(15) 2699-2702. 

A nice example is given by Lei et al. (2013), in which they studied adsorption of lysozyme on poly(2-(dimethylamino ethyl) methacrylate)-block-poly(methaaylic acid) (PDMAEMA-b-PMAA) diblock-copolymer brushes (Figure 5.14). Lysozyme has a relatively high isoelectric point (/p=ll.l) thus controlling its adsorption (on Si) by pH is too difficult. It has been shown that lysozyme adsorption decreases on weak base polyelectrolyte, PDMAEMA, and increases on weak acid polyelectrolyte, PMAA brushes. Authors show that the thickness of the PMAA block in PDMAEMA-b-PMAA is critical when the outer PMAA block is less than 10 nm, adsorption of the lysozyme increases with pH. Lysozyme adsorption reached to 16.4-fold more at pH 10 compared with its value at pH 4. At thicker regimes (>10nm), diblock-copolymer brush exhibited similar behavior to that of PMAA homopolymer brush. 

A cleavable, temperature-responsive polymeric cross-linker was utilized by Xu and cowoikers [111] to stabilize micelles from PEO-b-PAPMA-b-poly((Af,Af-diisopropylamino)ethyl methacrylate) triblock copolymer. The PNIPAm cross-linker contained activated ester end groups that were reacted with the primary amines on the PAPMA middle block. The trithiocarbonate moiety located at the middle of PNIPAm cross-linker could then be degraded by aminolysis to break the cross-links. Temperature-responsive micelles and vesicles from diblock and triblock copolymers were shell cross-linked via interpolyelectrolyte complexation [108, 112]. The cross-links formed by the electrostatic interactions of oppositely charged polyelectrolytes could be disrupted by the addition of SME. 

Topham PD, et al. Synthesis and solid state properties of a poly(methyl methacrylate)-block-poly(2-(diethylamino)ethyl methacrylate)-block-poly(methyl methacrylate) triblock copolymer. Macromolecnles... 

Poly(methyl methacrylate -block-t-butylaziridine) ABA type copolymer with MW 12000 butylaziridine (B) and MW 16000 Ambient to 600 CO, CH4, CO2, ethene, propene, isobutene, aziridine, methanol, methyl methacrylate, cc-methylstyrene, 2-phenyl-2-butene, 1 -t-butylamino-2-isopropenylamino-ethane, 2-r-butylaminoethyl-ethyl-isopropenylamine, 2-aminoethyl-2-r-butylaminoethyl-isopropenylamine, oligomers - principally butylaziridine based 287... 

Trialkylsilyl-protected oligo(ethylene glycol)methacrylates, 2- 2- (tert-butyldimethylsilyl)oxy]ethoxy ethyl methacrylate (1), and 2- 2-[2-[(ferf-butyldimethylsilyl)oxy] ethoxy] ethoxy ethyl methacrylate (2) (Scheme 7) were used for the synthesis of amphiphilic block copolymers by anionic poly-... 

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. 

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-... 

These materials, however, as a rule exhibit rather broad chemical composition distribution. Block copolymers may contain important amounts of parent homopolymer(s) [232,244,269], In any case, it is to be kept in mind that practically all calibration materials contain the end groups that differ in the chemical composition, size, and in the enthalpic interactivity from the mers forming the main chain. In some cases, also the entire physical architecture of the apparently identical calibration materials and analyzed polymers may differ substantially. The typical example is the difference in stereoregularity of poly(methyl and ethyl methacrylate)s while the size of the isotactic macromolecules in solution is similar to their syndiotactic pendants of the same molar mass, their enthalpic interactivity and retention in LC CC may differ remarkably [258,259]. 

Polyisobutylene-based block anionomers and cationomers, ( ), were prepared by Kennedy et al. (3) and used in drug release devices. Poly(2-dimethylami-no)ethyl methacrylate was quaternized after the block copolymer was synthesized to form a cationic block copolymer. 

The adsorption of block copolymers can be controlled by different stimuli, in particular by the pH since most of the brushes formed by block copolymers adsorption are polyelectrolyte brushes [129, 130], The group of Armes, for instance, studied the pH-controlled adsorption of a series of block copolymers [131, 132], In the case of copolymers bearing hydrophobic 2-(diethylamino)ethyl methacrylate groups (DEA) and a water-soluble zwiterionic poly(2-methacryloyl phosphoryl-choline) (MPC) block, they showed that at low pH the cationic DEA flatted to the anionic silicon surface while the MPC was in contact with the solution [132], At around neutral pH, micelles were formed in solution and adsorbed onto the surface because the DEA core was still weakly cationic. The MPC block formed the micelle coronas. Nevertheless, at higher pH the micelles became less cationic and the adsorption rate decreased. 

The different situations of the block copolyampholyte as a function of pH are depicted in Scheme. 1. The same order of deprotonation was observed in copolymers of poly(methacrylic acid) and poly(2-(diethylamino)ethyl methacrylate) [70, 71, 72, 75-77]. In copolymers of poly(methacrylic acid) [78] and poly(2/4-vinylpyridine), on the other hand, deprotonation of the pyridine hydrochloride takes place prior to deprotonation of the carboxyl [79-83] because in comparison to carboxylic functionalities amine hydrochlorides are the weaker acids and vinylpyridinium hydrochlorides the stronger ones. Thus, in the latter systems an isoelectric point (iep) is not observable, while in the first case polyzwitterions are formed which possess the highest amount of charges at that pH resulting in a polyelectrolyte complex (PEC). In the second case polymers with a minimal net charge built the PEC which is stabilized by hydrophobic interactions often accompanied by hydrogen bonding [79, 84-88]. 

ABA copolymers poly(methyl methacrylate)-polyisoprene-poly(methyl methacrylate) having polyisoprene with a high vinyl content as central block have been synthetized by Cole et al. 2I°. Dynamic mechanical properties of films of these ABA copolymers have been studied as a function of the copolymer composition, the temperature and the nature of the solvent (carbon tetrachloride, toluene, ethyl acetate, methylethyl ketone, dioxane) used for film preparation210. ... 

The masked disilene procednre was nsed by Saknrai and co-workers to synthesize two samples of diblock copolymers of 1,1-dimethyl-2,2-dihexylsilane (MHS) and 2-(trimethylsilyloxy)ethyl methacrylate, which differed only in the relative lengths of their blocks. Hydrolysis of the trimethylsilyl protecting groups gave the corresponding amphiphilic diblock copolymers, poly(l,l-dimethyl-2,2-dihexyldisilene)-fe-poly(2-hydroxyethyl methacrylate) (PMH S-fc-PHEMA), depicted in Pig. 22 [48]. 

Figure 6.37. Synthetic scheme for three-layer cross-linked micelles. Shown is the micellation of poly[(ethylene oxide)-block-glycerol monomethacrylate-block-2-(diethylamino)ethyl methacrylate] (PEO-GMA-DEA) triblock copolymers to the final onion-like" layered nanostructure. Reproduced with permission from Liu, S. Weaver, J. V. M. Save, M. Armes, S. P. Langmuir 2002, 18, 8350. Copyright 2002 American Chemical Society.

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