The equilibrium water content of some thermoplastic hydroxyalkyl methacrylate polymers

Abstract

SynopsisThe equilibrium water content (EWC) of thermoplastic 2-hydroxypropyl methacrylate and 2-hydroxyethyl methacrylate homopolymers from technical grade monomer and of copolymers of the latter with methyl methacrylate has been measured in distilled water and in phosphatebuffered saline (PBS). In distilled water, as expected, EWCs increased monotonically with the proportion of hydrophilic monomer in the polymer and showed only a small dependence on molecular weight. In contrast, the degree of swelling (and in same cases dissolution) and "freezable" water content of polymers in PBS were shown to be anomalously high and to be a consequence of ionization at pH 7.4 of methacrylic acid incorporated into the polymer in small quantity (< 1 mol I%) as an impurity. Initial studies indicated a strong relationship between copolymer molecular weight and small molecule permeability in distilled water.

New Hydrophobic IOL Materials and Understanding the Science of Glistenings

“…40 The equilibrium water content of various copolymers can also vary strongly depending on the concentration of salts (ionic strength) in the surrounding solution, for example, the aqueous humor or storage media. 41 The hygroscopic nature of polymers, and how this varies depending on temperature and ionic strength of the surrounding solution, is well explained and understood from the perspective of chemical potential equilibrium using concepts familiar to physical chemistry. 42 Due to the dynamics of the process of polymerization, it is clear that an entire piece of bulk material will not be completely connected, with polymer chains perfectly folded.…”

Preparation and characterization of polyelectrolyte copolymers containing methyl methacrylate and 2‐hydroxyethyl methacrylate. I. Polymers based on methacrylic acid

“…6 Measurements were performed at 35 k O.O5"C, taking the usual precautions, in previously described dilution viscometers. '…”

Gel Entrapment and Micro-Encapsulation: Methods, Applications and Engineering Principles

“…The growth rate and viability of the cells were not affected in these capsules (Gharapetian et al, 1986). Due to their good hydrolytic stability, Stevenson and Sefton (1988; used methacrylates to produce micro-capsules by polyelectrolyte complexation. Functionality could be introduced through the introduction of either MAA or DMAEMA to the polymer and the hydrophobic-hydrophilic balance in the remainder of the polymer can be adjusted by copolymerising with MMA, HEMA or hydroxypropyl methacrylate (HPMA).…”