Monomer reactivity ratios and glass-transition temperatures of copolymers based on dimethyl amino ethyl methacrylate and two structural hydroxy-functional acrylate isomers

Self-Assembled Injectable Nanocomposite Hydrogels Coordinated by in Situ Generated CaP Nanoparticles for Bone Regeneration

Due to the great similarity to the natural extracellular matrix and minimally invasive surgeries, injectable hydrogels are appealing biomaterials in cartilage and bone tissue engineering. Nevertheless, undesirable mechanical properties and bioactivity greatly hamper their availability in clinic applications. Here, we developed an injectable nanocomposite hydrogel by in situ growth of CaP nanoparticles (ICPNs) during the free-radical polymerization of dimethylaminoethyl methacrylate (DMAEMA) and 2-hydroxyethyl methacrylate (HEMA) matrix (PDH) for bone regeneration. The ICPNs are self-assembled by incorporation of poly-l-glutamic acid (PGA) with abundant carboxyl functional groups during the formation of carboxyl-Ca²⁺ coordination and further CaP precipitation. Furthermore, the carboxyl groups of PGA could interact with the tertiary amines of DMAEMA fragments and thus improve the mechanical strength of hydrogels. Upon mixing solutions of DMAEMA and HEMA bearing PGA, Ca²⁺, and PO₄^3-, this effective and dynamic coordination led to the rapid self-assembly of CaP NPs and PDH nanocomposite hydrogels (PDH/mICPN). The obtained optimal nanocomposite hydrogels exhibited suitable injectable time, an enhanced tensile strength of 321.1 kPa, and a fracture energy of 29.0 kJ/m² and dramatically facilitated cell adhesion and upregulated osteodifferentiation compared to hydrogels prepared by blending ex situ prefabricated CaP NPs. In vivo experiments confirmed the promoted osteogenesis, which shows a striking contrast to pure PDH hydrogels. Additionally, the methacrylate groups on the monomers could easily be functionalized with aptamers and thereby facilitate recognition and capturing of bone marrow stromal cells both in vitro and in vivo and strengthen the bone regeneration. We believe that our conducted research about in situ self-assembled CaP nanoparticle-coordinated hydrogels will open a new avenue for bone regeneration in the future endeavors.

Preparation of a poly(DMAEMA-co-HEMA) self-supporting microfiltration membrane with high anionic permselectivity by electrospinning

A cross-linked microfibrous anion exchange membrane with high ion permselectivity and robust mechanical properties was fabricated by electrospinning. Copolymer, poly N,N-dimethylaminoethyl methacrylate (DMAEMA)-co-2-hydroxyethyl methacrylate (HEMA), was selected as the electrospun material. Fourier transform infrared (FTIR) spectroscopy, 1HNMR and scanning electron microscopy (SEM) were employed to characterize the copolymer and microfibrous mat. The electrospinning optimal parameters were determined by orthogonal experiments. Formaldehyde vapor was applied to crosslink the mat. It was observed that the water sorption decreased from 75.7% to 30.4% as the crosslinking time increased from 20 h to 32 h. The robust mat with the high tensile strength of 4.62 MPa and 50% elongation at break was obtained at 24 h. The ion permeability of NO3−, Cl−, SO42− were 94, 91 and 87%.

Deciphering Physical versus Chemical Contributions to the Ionic Conductivity of Functionalized Poly(methacrylate)-Based Ionogel Electrolytes

Polymer-supported ionic liquids (ionogels) are emergent, nonvolatile electrolytes for electrochemical energy storage applications. Here, chemical and physical interactions between the ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMI TFSI) and three different cross-linked polymer scaffolds with varying chemical functional groups have been investigated in ionogels fabricated via in situ UV-initiated radical polymerization of methyl methacrylate (MMA), 2,2,2-trifluoroethyl methacrylate (TFEMA), or 2-(dimethylamino)ethyl methacrylate (DMAEMA) and a small amount of the cross-linker pentaerythritol tetraacrylate. Experimental findings demonstrate that the chemical functionality of the polymer side groups can significantly affect the degree of ion dissociation within the ionic liquid component of the ionogel and that the fraction of dissociated ions is the dominant factor in determining relative ionic conductivity in these materials, rather than any large differences in ion diffusivity. The MMA-based polymer scaffold exhibits a stronger attractive interaction with EMI TFSI (as evidenced by a higher activation energy of ionic conductivity) compared to the TFEMA- and DMAEMA-based scaffolds, resulting in consistently lower ionic conductivity values for MMA-based ionogels. These results may offer guidance toward the rational selection of future polymer-ionic liquid pairings in order to maximize the fraction of dissociated ions, thereby yielding highly conductive ionogel electrolytes.