Novel Amphiphilic Network Polymers Consisting of Polar, Short Primary Polymer Chains and Nonpolar, Long Cross-link Units Obtained by Free-Radical Cross-linking Monomethacrylate/Dimethacrylate Copolymerizations

Abstract

Solution copolymerizations of 2-hydroxyethyl methacrylate (HEMA), a polar monomer having a hydroxyl group, with 5 mol % (corresponding to 35.7 wt %) heneicosapropylene glycol dimethacrylate (PPGDMA-21), a nonpolar monomer having a poly(oxypropylene) unit, were carried out in MeOH at a dilution of 2/3 in the presence of different amounts of lauryl mercaptan as a chain transfer agent, providing novel amphiphilic vinyl-type network polymers consisting of polar, short primary polymer chains and nonpolar, long cross-link units. The vinyl-type network polymers formed via highly branched prepolymers have abundant dangling chains as their characteristic feature, especially when the primary polymer chain length is short, because both terminal parts of primary polymer chain would be dangling chains. The amphiphilicity of the resulting gels was checked by measuring their swelling ratios in the mixed solvents consisting of nonpolar tert-butylbenzene (t-BB) and polar MeOH; thus, with an increase in the MeOH volume percent, the gels shrank to the smallest swelling ratio at the start point (i.e., in pure t-BB), swelled gradually and then rather sharply beyond 20 vol %, reached the maximum swelling at about 70 vol %, and then shrank gradually up to a rather high swelling ratio at the terminal (i.e., in pure MeOH). The profiles of the solvent component dependencies of the swelling ratios are characteristic of novel amphiphilic gels. The conversion dependency of the characteristic swelling behavior suggests that the response of the gel obtained at an earlier stage of gelation was sharper than that of the gel obtained at a late stage of gelation. The influence of H 2O on the characteristic swelling behavior of resulting amphiphilic gels was examined by measuring their swelling ratios in the mixed solvents consisting of MeOH/H2O or acetone/ H2O in order to collect information about the role of cross-link units on the swelling behavior of amphiphilic gel.

Construction of Crosslink‐System‐Materials Utilizing Designed Network‐Polymer‐Precursor Modules

“…[22] This ideal NPP formation was developed to the preparation of novel amphiphilic polymers [11] and, moreover, amphiphilic CSMs. [37][38][39] As the latter case of controlling intramolecular crosslinking in the free-radical crosslinking monovinyl/divinyl copolymerization, we pursued the intramolecular crosslinking reaction to generate the net or loop structure as an origin of CSM, although the locally extensive occurrence of intramolecular crosslinking leads to microgelation. [3,[40][41][42][43][44] Eventually, we reached the preparation of novel loopstructures containing net polymers as the ultimate precursors of CSM consisting of microgel-like NPPs.…”

“…Thus, we could construct novel CSMs utilizing designed NPPs as modules, providing semi-interpenetrating polymer network (IPN) involving DAT networks and linear poly(BzMA), [46] and simultaneous-IPN between polymethacrylate and polyurethane networks, [47][48][49] novel amphiphilic CSMs [37][38][39]50,51] and patchwork-type CSMs, [52] and so on. Another example is concerned with the emulsion crosslinking (co)polymerization of multivinyl monomers, [53] especially focusing on the formation of reactive crosslinked polymer nanoparticles (CPNs) as models of microgels, with the intention of clarifying the correlation of the network structure with the reactivity of resulting CPNs which would be useful as functionalized polymeric materials.…”

Solid‐State NMR Investigations of the Unusual Effects Resulting from the Nanoconfinement of Water within Amphiphilic Crosslinked Polymer Networks

“…4). For the latter, the phase of the 908 pulse matched the phase of the carbon spin lock, which for isolated natural-abundance 13 C results in a standard full-size signal (vide infra).…”

“…That is, there is no contribution to the signals of Figure 8 from the PEG domains. The protons making the transfer to the 70-ppm 13 Cs are in the interface.…”

“…[11] Distinguishing features of amphiphilic crosslinked networks arise from the properties of the individual hydrophobic and hydrophilic polymer components, which can be trapped kinetically by subsequent covalent crosslinking between the dissimilar regimes. These materials [12] have many desirable features including unique swelling properties [13][14][15][16] important for anti-fouling coatings for the marine environment, [17] and inhibition of biomolecule adsorption or promotion of release [18] for use as potential pharmaceutical or biomedical devices. Such systems can be prepared readily, but often pose unique challenges in the characterization of their heterogeneous structures and morphologies.…”