Investigation of interpolymer complexation in swollen polyelectolyte networks using solid-state NMR spectroscopy

Abstract

Copolymer networks of poly(methacrylic acid) (PMAA) and poly(ethylene glycol) (PEG) exhibit large changes in their swelling behavior over a narrow pH range due to the reversible formation/dissociation of interpolymer complexes between the polymer chains. Intepolymer complexation occurs in copolymer gels of PMAA and PEG due to hydrogen bonding between protonated acid groups and the ether groups of the PEG. Because of their nature, these gels have been identified for use as delivery vehicles for macromolecular drugs. In this work, solid‐state, nuclear magnetic resonance nuclear Overhauser enhancement (NOE) experiments were performed to detect the molecular level complexation between PMAA and deuterated PEG in copolymer blends and crosslinked networks. For gels swollen in acidic media at room temperature or at 37 °C, strong enhancements were detected in the 13C resonance of the PEG carbons. The NOE was generated due to energy transfer between the rapidly rotating methyl group protons and the deuterated PEG carbons. The presence of the NOE was indicative of close packing of the polymer chains and was evidence of the presence of the intermacromolecular complexes. In basic solutions, no NOE was detected in the PEG, as the complexes were dissociated and the chains were separated in space. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2823–2831, 2000

Dynamics of poly(ethylene glycol)-tethered, pH responsive networks

“…Because the interactions between like molecules are counted twice, a factor of 2 is added. (4) From these equations, the heat of mixing can be expressed in the following form and is minimized when the difference between the solubility parameters of the liquids are as small as possible. Flory-Huggins solution theory shows that the free energy of mixing (6) is highly dependent on the molecular weight of the polymer.…”

“…Tethered polymer networks have received considerable attention for their use in modifying surface adhesion and friction [1][2][3], drug delivery systems [4][5][6][7][8], and bioadhesives [1,2,9,10]. Biomimetic systems, biomaterials that mimic a biological environment to elicit a desired cellular response [11], have also utilized tethered macromolecules to effectively enhance cellular adhesion [12][13][14] or prevent protein adsorption [15].…”

The Oral Delivery of Proteins Using Interpolymer Polyelectrolyte Complexes

“…Interpolymer complexes are often prepared by mixing aqueous solutions containing oppositely charged polymers at a specific pH resulting in the formation of interpolymer PECs exhibiting varied morphologies and functionalities as dictated by their chemical composition [106,107]. However, tailoring the use of these interpolyelectrolyte structures to surmounting the barriers inherent in oral protein delivery involves careful selection of complementary polycations and polyanions, which interact optimally providing a robust network suitable for the incorporation and protection of proteins intended for oral administration.…”

Thermodynamic Studies on Some Multicomponent Intermacromolecular Complexes of Varying Composition Involving an Acrylic Polymer, a Polyelectrolyte and a Nonionic Polymer

“…Studies on intermacromolecular complexes formed between macromolecules with complementary binding sites have aroused considerable interest in the filed of polymer science, these complexes have not only provided new materials, but they can also be tailored to special applications in industry and medicine [1][2][3][4][5][6][7][8][9][10][11][12] . Though a considerable amount of work have been reported in the literature regarding the fundamental studies on polymer-polymer interactions, and applications of intermacromolecular complexes, but detailed thermodynamic studies on their systems are particularly lacking.…”