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Synthesis of poly(acrylic acid) nanogels by preparative pulse radiolysis
被引:71
作者:
Ulanski, P
[1
]
Kadlubowski, S
[1
]
Rosiak, JM
[1
]
机构:
[1] Tech Univ Lodz, Inst Appl Radiat Chem, PL-93590 Lodz, Poland
关键词:
polymer;
crosslinking;
hydrogel;
nanogel;
D O I:
10.1016/S0969-806X(01)00549-7
中图分类号:
O64 [物理化学(理论化学)、化学物理学];
学科分类号:
070304 ;
081704 ;
摘要:
Nanogels are sub-micron size, water-swellable crosslinked structures of hydrophilic polymers. In this work a radiation-based synthesis method that has been previously tested for neutral polymers is applied for production of nanogels of a synthetic polyelectrolyte-poly(acrylic acid) (PAA). In this technique dilute, deoxygenated PAA solution (pH 2) circulating in a closed loop is subjected to pulse irradiation with fast electrons. In each pulse many tens of radicals are instantaneously formed on every macromolecule. One of the major reaction paths of these radicals is intramolecular recombination leading to the formation of nanogels. It is demonstrated that radiation-induced reactions in our system show a typical feature of intramolecular crosslinking, i.e. a strong decrease in dimensions of a polymer coil without an accompanying decrease in molecular weight. In accordance with expectations based on earlier observations on non-polar polymers, intramolecular recombination of PAA-derived radicals proceeds according to non-classical kinetics. A model of non-homogeneous kinetics with time-dependent rate constant has been applied to describe this behaviour and the relationship between kinetic parameters and initial average number of radicals per chain is briefly discussed. The weight-average molecular weight of the products is influenced by side reactions, mainly degradation (chain breakage) and intermolecular crosslinking. (C) 2002 Elsevier Science Ltd. All rights reserved.
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页码:533 / 537
页数:5
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