Effect of dangling chains on the structure and physical properties of a tightly crosslinked poly(ethylene glycol) network


Autoria(s): Radi, Babak; Wellard, R. Mark; George, Graeme A.
Data(s)

2013

Resumo

Major imperfections in crosslinked polymers include loose or dangling chain ends that lower the crosslink d., thereby reducing elastic recovery and increasing the solvent swelling. These imperfections are hard to detect, quantify and control when the network is initiated by free radical reactions. As an alternative approach, the sol-​gel synthesis of a model poly(ethylene glycol) (PEG-​2000) network is described using controlled amts. of bis- and mono-​triethoxy silyl Pr urethane PEG precursors to give silsesquioxane (SSQ, R-​SiO1.5) structures as crosslink junctions with a controlled no. of dangling chains. The effect of the no. of dangling chains on the structure and connectivity of the dried SSQ networks has been detd. by step-​crystn. differential scanning calorimetry. The role that micelle formation plays in controlling the sol-​gel PEG network connectivity has been studied by dynamic light scattering of the bis- and mono-​triethoxy silyl precursors and the networks have been characterized by 29Si solid state NMR, sol fraction and swelling measurements. These show that the dangling chains will increase the mesh size and water uptake. Compared to other end-​linked PEG hydrogels, the SSQ-​crosslinked networks show a low sol fraction and high connectivity, which reduces solvent swelling, degree of crystallinity and the crystal transition temp. The increased degree of freedom in segment movement on the addn. of dangling chains in the SSQ-​crosslinked network facilitates the packing process in crystn. of the dry network and, in the hydrogel, helps to accommodate more water mols. before reaching equil.

Formato

application/pdf

Identificador

http://eprints.qut.edu.au/65245/

Publicador

Royal Society of Chemistry

Relação

http://eprints.qut.edu.au/65245/1/Radi_DAngling_chains_Soft_Matter_2013.pdf

DOI:10.1039/c3sm27819k

Radi, Babak, Wellard, R. Mark, & George, Graeme A. (2013) Effect of dangling chains on the structure and physical properties of a tightly crosslinked poly(ethylene glycol) network. Soft Matter, 9(12), pp. 3262-3271.

http://purl.org/au-research/grants/ARC/DP 0877988

Direitos

Copyright 2013 The Royal Society of Chemistry

Fonte

School of Chemistry, Physics & Mechanical Engineering; Institute for Future Environments; Science & Engineering Faculty

Palavras-Chave #030300 MACROMOLECULAR AND MATERIALS CHEMISTRY #030500 ORGANIC CHEMISTRY #poly ethylene glycol #Solid State Magic angle spinning NMR #cross-linking #sol-gel
Tipo

Journal Article