کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5188559 1381160 2006 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Gelation and swelling behavior of end-linked hydrogels prepared from linear poly(ethylene glycol) and poly(amidoamine) dendrimers
موضوعات مرتبط
مهندسی و علوم پایه شیمی شیمی آلی
پیش نمایش صفحه اول مقاله
Gelation and swelling behavior of end-linked hydrogels prepared from linear poly(ethylene glycol) and poly(amidoamine) dendrimers
چکیده انگلیسی
Linear α,ω di-epoxide-terminated poly(ethylene glycol) of molar mass 4000 g mol−1 was end-linked with amine-terminated poly(amidoamine) (PAMAM) dendrimers of generations 0, 2, and 4 in water to prepare architecturally well-defined copolymer hydrogels. The gelation and equilibrium swelling of the gels in water were characterized while systematically varying the polymer concentration at preparation, dendrimer generation, and mole ratio of dendrimer endgroups to PEG endgroups. The Ahmad-Rolfes-Stepto (ARS) theory of non-linear polymerization was applied to predict conditions favoring gelation, and to estimate the extent of reaction of amine and epoxide groups. Hydrogels having a large stoichiometric excess of amines over epoxides exhibited “superabsorbent” behavior upon extraction and equilibrium swelling in pure water. The mole ratio of amines to epoxides (equivalently, the mass fraction of dendrimers) was the most important factor governing superabsorbent behavior, although the polymer volume fraction at crosslinking and dendrimer generation also affected swelling to a lesser extent. The superabsorbency arises in part from protonation of the dendrimer amine endgroups at external pH = 7, which is supported by the drastic shrinkage of the most highly swelling gels in aqueous NH4OH at pH = 11. Equilibrium swelling at pH = 7 was noticeably enhanced in gels having a high soluble fraction and high mass fraction of dendrimers. End-linking of linear polymer precursors to PAMAM dendrimers can potentially produce novel copolymer gels that combine attractive properties of the linear precursors with high swelling and pH-responsive behavior of PAMAM-containing networks.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Polymer - Volume 47, Issue 24, 8 November 2006, Pages 8173-8182
نویسندگان
, ,