US EPA

5180388 

Journal Article 

Novel highly branched polyester nanoparticles(I) - Light-scattering characterization 

Ma, RJ; Wu, Q 

1998 

Yes 

Chemical Research in Chinese Universities
ISSN: 1005-9040 

HIGHER EDUCATION PRESS 

BEIJING 

14 

1 

70-75 

WOS:000072402400013 

Highly branched polyester nanoparticles (HBPN) with a weight-averaged molecular weight of 1.2X10(4) g/mol and a hydrodynamic radius of 4.3 nm were prepared by the polycondensation of phthalic anhydride and pentaerythritol at 142 degrees C under vacuum. The laser light-scattering (LLS) characterization of HBPN in both N, N-dimethylformamide (DMF) and the buffer (pH = 12) was accomplished. DMF is a good solvent for HBPN and there is no aggregation or association between individual particles of HBPN in DMF at room temperature. In the buffer, there exists a very small amount of HBPN aggregates whose size is about 10 times larger than that of individual HBPN particles, There is a balance between individual HBPN particles and the HBPN aggregates, so that HBPN is stable in the buffer and most of HBPN remain as individual particles. The particle size of HBPN can be controlled by the copolymerization time. A combination of static and dynamic LLS results, i.e., M-w and R-b, enables us to estimate that on average each HBPN particle (dentritic-like cluster) contains 4 layers or generation. 

branched polymer; nanoparticles; laser light scattering; characterization