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Starch nanoparticles (SNP) were modified with synthetic polymers using the “grafting to” approach and nitroxide-mediated polymerization. SG1-capped poly(methyl methacrylate-co-styrene) (P(MMA-co-S)...

Starch nanoparticles (SNPs) were used to partially replace petroleum-based polymers in a biobased latex adhesive application. Modification of SNPs (i.e., increasing cross-link density, functionalizing using a sugar-based monomer, and tuning SNP hydrophobicity) was performed prior to their incorporation in a semibatch emulsion polymerization to produce stable SNP-based latexes. SNP loadings and latex solids content were varied to study their effect on latex stability and properties (e.g., viscosity, particle size, adhesive properties, particle morphology). Stable and low viscosity latexes with up to 45 wt % SNP loadings and 55 wt % latex solids were achieved. STEM images confirmed the presence of the core–shell morphology, where SNPs were located in the particle cores and provided biocontent, while the acrylic polymers were present as the shell and governed the application properties. Pushing the limits of SNP loading and latex solids was shown to come at a cost to adhesive and other properties.

The incorporation of charge within in situ covalently gelling poly(oligo ethylene glycol methacrylate) (POEGMA) precursor polymers enables the fabrication of hydrogels that exhibit both pH-responsive swelling and tunable network structures due to multimechanism cross-linking interactions. The gelation times, swelling responses, degradation kinetics, and mechanics of the resulting gels were strongly influenced by both the type of charge(s) incorporated and pH, with both amphoteric gels and anionic gels showing clear evidence of dual network formation. While the amphoteric dual network was anticipated due to charge interactions, the mechanism of the 5-fold enhancement in mechanical properties observed with the anionic gel relative to the neutral gel was revealed by isothermal titration calorimetry and small-angle neutron scattering to relate to the formation of a zippered chain structure based on dipole–dipole interactions. Consequently, rational design of the chemistry and the microscopic network structure...

Injectable, dual-responsive, and degradable poly(oligo ethylene glycol methacrylate) (POEGMA) hydrogels are demonstrated to offer potential for cell delivery. Charged groups were incorporated into hydrazide and aldehyde-functionalized thermoresponsive POEGMA gel precursor polymers via the copolymerization of N,N'-dimethylaminoethyl methacrylate (DMAEMA) or acrylic acid (AA) to create dual-temperature/pH-responsive in situ gelling hydrogels that can be injected via narrow gauge needles. The incorporation of charge significantly broadens the swelling, degradation, and rheological profiles achievable with injectable POEGMA hydrogels without significantly increasing nonspecific protein adsorption or chronic inflammatory responses following in vivo subcutaneous injection. However, significantly different cell responses are observed upon charge incorporation, with charged gels significantly improving 3T3 mouse fibroblast cell adhesion in 2D and successfully delivering viable and proliferating ARPE-19 human retinal epithelial cells via an "all-synthetic" matrix that does not require the incorporation of cell-adhesive peptides.

The enhanced mechanics, unique chemistries, and potential for domain formation in interpenetrating network (IPN) hydrogels have attracted significant interest in the context of biomedical applications. However, conventional IPNs are not directly injectable in a biological context, limiting their potential utility in such applications. Herein, we report a fully injectable and thermoresponsive interpenetrating polymer network formed by simultaneous reactive mixing of hydrazone cross-linked poly(N-isopropylacrylamide) (PNIPAM), and thiosuccinimide cross-linked poly(N-vinylpyrrolidone) (PVP). The resulting IPN gels rapidly (

While injectable, in situ gelling hydrogels have attracted increasing attention in the biomedical literature due to their minimally invasive administration potential, little is known about the internal morphology of these hydrogels and thus how to engineer precursor polymer compositions to achieve desired hydrogel properties. In this paper, the internal morphology of injectable in situ gelling hydrogels based on hydrazide and aldehyde-functionalized poly(oligoethylene glycol methacrylate) precursors with varying lower critical solution temperatures (LCSTs) is investigated using a combination of spectrophotometry, small-angle neutron scattering, and light scattering. If two precursor polymers with similar LCSTs are used to prepare the hydrogel, relatively homogeneous hydrogels are produced (analogous to conventional step-growth polymerized hydrogels); this result is observed provided that gelation is sufficiently slow for diffusional mixing to compensate for any incomplete mechanical mixing in the double-b...

Hyperbranched polymers are synthesized via a cobalt(II) mediated emulsion copolymerization of methyl methacrylate and diethylene glycol dimethacrylate. The concentration of divinyl monomer and chain transfer activity have to be balanced in order to prevent gelation of the polymer particles. The physiochemical properties of the cobalt(II) complex, specifically the intrinsic chain transfer activity and the partitioning behavior, play a crucial role in governing the polymer architecture (i.e., branched versus cross-linked). Furthermore, an empirical correlation, based on the chain transfer frequency and the divinyl monomer mol fraction, is presented and validated with the results obtained in emulsion polymerization as well as with available literature data.