Poly(methacrylic acid)-l-Polyisobutylene:  A Novel Polyelectrolyte Amphiphilic Conetwork

Abstract

For the first time, a reliable procedure for synthesizing new acidic polyelectrolyte-containing amphiphilic conetworks (APCNs), poly(methacrylic acid)-l-polyisobutylene (PMAA-l-PIB), is described. The thorough characterization of the synthesis products is also presented through elemental analysis, differential scanning calorimetry (DSC), and basic swelling studies. Three series of APCNs were successfully synthesized in wide composition ranges by the macromonomer method using exact bifunctional methacrylate-telechelic PIB cross-linkers (MA−PIB−MA) of three different molecular weights (M n): 2000, 5000, and 13000. The MA−PIB−MA macromolecular cross-linkers were prepared via quasiliving carbocationic polymerization. To prevent phase separation and thus insufficient network formation during synthesis, the conetworks were synthesized by thermally initiated free radical copolymerization of MA−PIB−MA and trimethylsilyl methacrylate, a hydrophobized precursor of methacrylic acid. After the next critical synthetic step, the quantitative hydrolytic cleavage of the trimethylsilyl groups from the poly(trimethylsilyl methacrylate) chains in the resulting precursor conetworks, 5−8 different compositions of each PMAA-l-PIB conetwork series were obtained. The low amounts of extractables (<8−10%) and elemental analysis data showed high copolymerization yields and close to target compositions. DSC investigations indicated phase separation of the PMAA and PIB components. As all PMAA-l-PIB conetworks are optically clear materials, the extent of phase separation must occur on the nanometer scale. The amphiphilic character of these new materials was demonstrated by uniform swelling of PMAA-l-PIB conetworks in both aqueous and apolar media which indicates cocontinuous nanophasic morphology.

Tailoring pH-responsive acrylic acid microgels with hydrophobic crosslinks for drug release

“…5, it was apparent that by increasing the crosslinking density and the hydrophobic content, the size of the microgels decreased, as anticipated since the crosslinks avert the microgel from expanding. This expected trend, that has been observed before in microgels 4,39 as well as macrogels, 40 was only apparent in high pH solutions in which the AA units were ionised. At lower pH values, the polymer chains of the microgels were not extended, i.e.…”

Wide Bicontinuous Compositional Windows from Co-Networks Made with Telechelic Macromonomers

“…42,43 Later studies confirmed that the presence of random cross-links frustrates the formation of highly ordered phases, 44 resulting in disordered bicontinuous structures under appropriate conditions. 45,46,47,48 However, these studies have relied on random co-polymerization of monomers with a telechelic macromonomer as a cross-linker, leading to uncontrolled network architectures. 45,46,47,48,49 Furthermore, bicontinuity has most commonly been established through measurements of the swelling ratios in water and non-polar solvents, which can be complicated to interpret due to the possibility for solvent-induced structural rearrangements.…”

Evaluating a simple blending approach to prepare magnetic and stimuli-responsive composite hydrogel particles for application in biomedical field

“…P(S-NIPAM-MAA-PEGMA) hydrogel particles exhibit different morphology with central darker parts possibly represents the hydrophobic PS rich segment. The hydrophobic-hydrophobic interactions among PS segments in amphiphilic P(S-NIPAM-MAA-PEGMA) conetwork led to the reorientation of polymer chains forming core-shell type microgels in water [60][61][62][63][64]. Compared to P(S-NIPAM-MAA-PEGMA) hydrogel particles the size of Fe 3 O 4 / SiO 2 /P(S-NIPAM-MAA-PEGMA) composite hydrogel particles decreases after blending with Fe 3 O 4 / SiO 2 nanocomposite particles.…”

“…MMA/MAA was added to improve the solubility of styrene in the aqueous dispersion media for facilitating smooth copolymerization with NIPAM as the latter in absence of MMA/MAA may produce larger proportion of water soluble homopolymer due to its comparatively high reaction rate. The hydrophobichydrophobic interactions among hydrophobic PS-PMMA or PS segments in the prepared conetworks are expected to form microgels in water, a phenom-enon generally observed for amphiphilic copolymer networks consisting of hydrophilic and hydrophobic polymer segments [60][61][62][63][64] 4 OH and other chemicals were of analytical grade. Ethanol and deionized water was distilled using a glass (Pyrex) distillation apparatus.…”