Synthesis, physical characterization, and biological performance of sequential homointerpenetrating polymer network sponges based on poly(2-hydroxyethyl methacrylate)

Abstract

A limitation in the use of hydrophilic poly(2-hydroxyethyl methacrylate) (PHEMA) sponges as implantable devices is their inherently poor mechanical strength. This precludes proper surgical manipulation, especially in the eye where the size of the implant is usually small. In this study a new method was developed to produce mechanically stronger PHEMA sponges. Sequential homointerpenetrating polymer network (homo-IPN) sponges were made by using HEMA as the precursor for generating both the first network and the successive interpenetrated networks. Following the formation of network I, the sponge was squeezed to remove the interstitial water, soaked in the second monomer (also HEMA), and squeezed again to remove the excess monomer from the pores before being subjected to the second polymerization leading to the formation of network II. Two two-component IPN sponges (K2 and K4) with increasing HEMA content in the network II and a three-component IPN sponge (K3) were produced, and their properties were compared to those of a homopolymer PHEMA sponge (control). Apart from elongation, the tensile properties were all significantly enhanced in the IPN sponges; the water content was the same as in the control sponge, except for sponge K4, which was lower. Light microscopy revealed similar pore morphologies of the control and IPN sponges K2 and K3, and the majority of the pores were around 25 microm. Sponge K4 displayed smaller pores of around 10 microm. Cellular invasion into the sponges was examined in vitro (incubation with 3T3 fibroblasts) and in vivo (implantation in rabbit corneas). Although the in vitro assay detected a change in the cell behavior in the early stage of invasion, which was probably due to the formation of IPNs, such changes were not reflected in the longer term in vivo experiment. There was a proper integration of sponges K2 and K3 with the corneal stroma, but much less cellular invasion and no neovascularization in sponge K4. We concluded that IPN formation is a valid method to enhance the strength of PHEMA sponges, provided that the content of HEMA in the successive networks is not too high.

New resin gel for uranium determination by diffusive gradient in thin films technique

“…Hydroxyethyl methacrylate (HEMA)-ethylene dimethacrylate (EDMA) copolymer was chosen as one of the well documented potentially useful gels [19][20][21][22][23]. Unfortunately no applicable gels were obtained in spite of the fact that synthesis of new gels was experienced under various polymerization conditions (percentage of EDMA cross-linker, thermal and UV initiation, content of water as porogenous aid).…”

AlphaCor artificial cornea: clinical outcome

“…[5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] Several complications, associations, and risk factors have been identified. [21][22][23][24][25] The indications and surgical techniques have been evolving with experience.…”

Mechanical properties of semi-interpenetrating polymer network hydrogels based on poly(2-hydroxyethyl methacrylate) copolymer and chitosan

“…The simultaneous interpenetration of two crosslinked polymers is expected to impart outstanding mechanical properties that are due to a synergistic effect induced by the enforced compatibility of the components [2][3][4]. Hydrogels are described as hydrophilic polymers that are swollen by water, but do not dissolve in water.…”