PHEMA backbone

It was demonstrated above that both the value and the stability of the refractive index modulation are far better for block copolymers than for statistical copolymers with comparable azobenzene content. But the influence of the morphology and the domain size on the refractive index modulation remains unclear. To investigate this we chose a block copolymer series with three different morphologies lamellar, cylindrical, and spherical. In Fig. 28 the growth and decay for different morphologies of the block copolymers 10 (Afn 45,900gmoP1 azobenzene content 31 wt%) and 11 (Mn 42,400gmon1 azobenzene content 25 wt%), which are based on a PMMA-PHEMA backbone, are shown [66, 113]. Both block copolymers exhibit a similar... 

ATRP was also combined with other polymerization methods in the preparation of polymer clay nanocomposites. Yang and coworkers reported the preparation of poly(L-lactide) (PLLA) comb polymer brushes on the surface of sihcate layers by using a combination of in-situ ATRP and ROP (Figure 10.7) [34]. An ATRP initiator with a quaternary ammonium salt end group was intercalated into the interlayer spacing of clay layers via ion exchange. In-situ ATRP of hydroxyethyl methacrylate (HEMA) in the presence of CuBr and bipyridine afforded the PHEMA backbone. PLLA comb polymers were grown from the PHEMA backbone by ROP. Because... 

When the nitrosyl-polymer composite Ru-pHEMA was exposed to low-power UV hght (5—10 mW), rapid release of NO was observed (detected by NO-sensitive electrode). The photorelease of NO was also confirmed through the nitrosylation of reduced myoglobin (Figure 11). Covalent attachment of the Ru nitrosyl complex to the organic backbone... 

By using ATRP, poly(2-hydroxyethyl methacrylate)- f-PS (PHEMA-g-PS) and PHEMA-g-poly(n-butyl acrylate) (42) were synthesized. The backbone, comprised... 

Metallocene and ATRP techniques were combined for the synthesis of graft ter- and quaterpolymers poly(ethylene-co-styrene) as backbone and one of PS, PMMA, PMMA- -PS, PMMA-6-polymethylacrylate, and PMMA-6-PHEMA as grafted chain (44). The aromatic rings of styrene were partially brominated and the C-Br groups that were formed were subsequently used as initiating sites for ATRP polymerization. 

PMEGA) that is less hydrophobic due to the absence of the methylene units attached to the polymer backbone is also reported to be water insoluble (Tanaka et al, 2000). In contrast, the strucmral isomer poly(2-hydroxyethyl methacrylate) (PHEM A) is water soluble at low molar mass (DP<30), exhibits LCST behavior at intermediate molar mass (30 < DP < 50) and is insoluble at higher molar mass. These different properties of PMEGA and PHEMA demonstrate that subtie differences in the hydrophihc-hydrophobic balance of the polymers as well as that the location of both hydrophilic and hydrophobic moieties can have strong effects on the solubility and thermoresponsive behavior of the polymers. 

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