142 Advances in Polymer Science Editorial Board: A. Abe. A.-C ...

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198 J. Roovers, B. Comanita Fig. 5. Dependence of the hydrodynamic radius of poly(benzyl ether) dendrimers on molecular weight;m monodendron; o tridendron; data on low MW polystyrene (D) in a good solvent are included for comparison ed especially for the low MW dendrimers. The same study [76] reported results in three different solvents of decreasing polarity, water at pH 8.0 with 0.1 mol/l NaCl, methanol and n-butanol. At low MW up to the fourth generation, R h~M 0.4 and the dimensions of the dendrimers vary little with the solvent quality. This behavior is comparable to that of low MW organic compounds and oligomers. For example, Yamakawa et al. showed that poor and good solvent distinctions disappear for polystyrene oligomers with MWR h (MeOH)>R h (n-BuOH). Such behavior is typical of polymers and reflects the influence of solvent on long-range interactions. It is remarkable that hydrodynamic radii of PAMAM dendrimers in MeOH based on the ammonia core are in good agreement with the hydrodynamic radii of the dendrimers based on ethylenediamine core [3, 77]. These results have also been included in Fig. 4. Intrinsic viscosity results on DAB(CN) x and DAB(NH 2 ) x have been quoted in various publications [5, 71, 78]. Unfortunately, the solvent and experimental conditions are not specified. R h is found to increase by a constant increment for five generations. In a double logarithmic plot of R h against MW it is found that the slope decreased from slightly larger than 0.4 at low MW to about 0.3 at high MW. Intrinsic viscosities of four generations of carbosilane dendrimers [79] (see Fig. 3a for structure) and four generations of poly(dimethylsiloxane) dendrimers [80] lead to R h–M n dependencies with n=0.4 for these low MW dendrimers.
Dendrimers and Dendrimer-Polymer Hybrids 199 The studies of R g as well as R h and R h of a number of dendrimer systems establish a transition from n=0.45+0.05 to n=0.25+0.05 dependence on MW as shown in Figs. 4 and 5. This result is qualitatively consistent with the simulation results and has several consequences. Because [h]~R h 3 /M, the value of [h] will increase with the MW of the dendrimer when n>1/3, be independent of MW when n=1/3, and decrease with MW when n1/3 but increases at high generation when n
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142 Advances in Polymer Science Edi
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Branched Polymers I Volume Editor:
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Volume Editor Dr. Jacques Roovers I
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Preface While books have been writt
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Contents Synthesis of Branched Poly
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Synthesis of Branched Polymers by C
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72 N. Hadjichristidis, S. Pispas, M
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100 N. Hadjichristidis, S. Pispas,
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Poly(macromonomers): Homo- and Copo
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Poly(macromonomers), Homo- and Copo
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Page 155 and 156: Poly(macromonomers), Homo- and Copo
Page 187 and 188: Dendrimers and Dendrimer-Polymer Hy
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Page 237 and 238: Author Index Volumes 101-142 Author
Page 239 and 240: Author IndexVolumes 101-142 231 Dun
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Page 247 and 248: Subject Index Addition-fragmentatio
Page 249 and 250: Subject Index 241 Microphases 11z,
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142 Advances in Polymer Science Editorial Board: A. Abe. A.-C ...

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