Catalyst HMTETA

The polymerization of 2-(diethylamino)ethyl methacrylate, DEAEMA, was studied under different conditions. It was shown that the best system providing narrow molecular weight distribution polymers involved the use of p-toluenesulfonyl chloride/CuCl/HMTETA as the initiator/catalyst/ligand at 60 °C in methanol [72]. Taking advantage of these results, well-defined PDEAEMA-fr-PfBuMA block copolymers were obtained. The synthesis was successful when either fBuMA or DEAEMA was polymerized first. Poor results with bimodal distributions were obtained when CuBr was used as the catalyst. This behavior was attributed to the poor blocking efficiency of PDEAEMA-Br and the incomplete functionalization of the macroinitiator. 

PPO-b-PDEAEMA block copolymers were prepared using a PPO macroinitiator, synthesized as previously described. The copolymerization was performed in methanol at 55 °C using CuCl as the catalyst and HMTETA as the ligand [127]. The yield was quantitative and the molecular weight distribution equal to 1.20. 

VAc] = 10.8 M, VAc/EBiB/catalyst = 150 1 1 EBiB ethyl 2-bromoiso-butyrate HMTETA 1,1,4,7,10,10-Hexamethyltriethylenetetramine TPMA tris[(2-pyridyl)-... 

A continuous column reactor packed with siUca-gel-supported CuBr-HMTETA catalyst for ATRP of MMA exhibits high catalyst retention, high catalytic activity, and good stability up to 100 h (Fig. 21). Moreover, the product solution is colorless... 

The complexes of basic ligands, especially when their stability constants in the absence of protonation are relatively low (e.g., Cu complex of HMTETA) are very much destabilized in acidic media. The complex of the basic Me TREN is markedly more destabilized in acidic media than the complex of the less basic ligand TPMA. From this point of view, TPMA is a promising candidate for ARGET and ICAR reactions. The complex of Me TREN can also be used but in conjunction with excess base (or excess free ligand) that will trap the acid generated during the redox process. In the presence of side reaction, the amount of catalyst actually present in the system... 

Block copolymerization (PBLG-b-PMMA) In a dry round bottomed flask charged Cu(I)Br and macro-initiator were dissolved in DMF (abs.), the solution was degassed by bubbling with nitrogen for 15 minutes. The ligand (HMTETA), MMA and anisole as internal standard were added. The poljmerization was done at 80 °C. After the desired polymerization time the catalyst was removes by an alox column and the polymer was precipitated into methanol, isolated and reprecipitated two times. 

MMA/EMADTC/Cu(I)Br/HMTETA = 200/1/1/1 in 50% (v/v) anisole offered a well-controlled polymerization imder UV light irradiation. The polymerization process proceeded very slowly due to the slow activation of the dormant species by copper catalyst at 30°C in the dark, while it went on 25 times faster upon UV irradiation [QIN 01, KWA 11, KWA 10],... 

Compared to DMAEMA, there are only a few reports on the ATRP of DEAEMA polymer brushes [20,52,53]. Our efforts involved the SC-ATRP of PDEAEMA from silanized silicon (Si) wafer substrates, and different catalyst (CuBr, CuCl), initiator (Si-Br, Si-Cl), solvent (IPA/H2O, methanol, toluene, THE, anisole), and reaction temperature (25°C-90°C) combinations were examined. The thickest PDEAEMA brushes were obtained using CuCl/ CUCI2/HMTETA as the catalyst system with a 2-bromoisobutyryl-based initiator, MeOH as the solvent, and a reaction temperature of 60°C. Under these conditions, the maximum PDEAEMA dry layer thickness obtained was 19 nm after polymerization for 72 h. 

The solvent dependency of Katrp was also examined in terms of Kamlet-Taft parameters for 11 solvents and then extrapolated to cover catalyst activity in a total of 28 solvents, including water. The log(KATRp) values measured in this work for Cu Br/l,l,4,7,10,10-hexamethylttiethylenetetramine (HMTETA) + MBriB are plotted against values predicted by the Kamlet-Taft relationship the line representing values predicted by the Kamlet-Taft relationship is shown in Figure 8. Predicted values of Katrp for 16 organic solvents and water are also provided, based on these solvent-independent coefficients and the appropriate solvatochromic parameters. 

Figure 12 illustrates that while the Cu7N,N,N, N", N"-pentamethyldiethylenetriamine (PMDETA) complex is active, it disproportionates in aqueous ATRP. On the other hand, ligands such as bpy, HMTETA, and TPMA can be used in aqueous media, although with rather different activities. If necessary, catalyst disproportionation in water can be suppressed by using an appropriate cosolvent or by addition of a pseudoligand that will stabilize Cu versus Cu , such as pyridine, which allows... 

Recently, we have synthesized a series of well-defined stimuli responsive, water-soluble, fuUerene-containing polymers using ATRP. A well-defined alkali-soluble Co) end-capped poly(methacryhc acid) was synthesized by ATRP using group protecting chemistry [82]. A well-defined, stable Gl-terminated poly(tert-butyl methacrylate) (PtBMA) was synthesized using p-toluenesulfonic acid (p-TSA) as an initiator in the presence of CuCl/HMTETA catalyst complex at 90 °C. The Cl-terminated PtBMA was further used to perform in the presence of excess of Cso... 

Ampholytic block copolymer contains both positive and negative charges on different segments of the diblock copolymer. Stimuli responsive, water-soluble polyampholyte-Qo polymer has also been synthesized by ATRP [86]. First, a well-defined, stable Cl-terminated P(tBMAio2-b-DMAEMA,57)-Cl block copolymer was prepared by ATRP in the presence of the CuCl/HMTETA catalyst system [87]. ATRA of P(tBMA-b-DMAEMA)-Cl macro-initiator to excess C > using the same catalyst system at 90 °C offered a well-defined block copolymer-C ) (Scheme 3.5). Subsequently, the specific hydrolysis of P(tBMA-b-DMAEMA)-f)-C ) to remove the tert-butyl group in the presence of concentrated HCl in 1,4-dioxane offered well-defined polyampholyte P(MAA-b-DMAEMA)-b-Ca) polymer, which is responsive to both pH and temperature. 

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