Christopher M. Kozak

Cultivated kelps are a scalable marine feedstock for renewable polymers, but regional aquaculture supply chains lack engineering benchmarks for the alginate yield and quality. Here, we apply a lower-hazard citrate-based process to quantify bioplastics-relevant alginate metrics across cultivated northeast Pacific kelps from commercial farms in British Columbia (Canada) and Alaska (USA). Ten blade biomass samples spanning five species were screened. Two samples failed to undergo phase separation after extraction and centrifugation, indicating biomass-dependent extractability as a process risk. For the remaining eight feedstocks, yields ranged from 11.95 to 26.11% (dry weight). Weight-average molar mass (Mw) ranged from 36.6 to 623 kDa, with 7/8 samples exceeding 400 kDa. Uronic acid composition spanned M/G = 0.14–1.38, with variation in G/M block compositions (block fractions and block lengths) relevant to cross-linking. Multivariate analysis resolved dominant gradients linking the uronic acid composition and molar mass distributions. The studied kelps were evaluated in the context of known seasonal, tissue-specific, and environment-driven effects and climate-related stressors that can alter productivity. Collectively, these results provide a regional benchmark for lower hazard alginate production from cultivated kelps and an engineering screening framework to support consistent feedstock selection for scalable manufacturing of alginate-based films, coatings, and related bio-based materials.

Liquid-phase exfoliation (LPE) is a viable method for the large-scale production of two-dimensional (2D) graphene; however, toxic solvents must be replaced. The microwave synthesis of sustainable succindiamide solvents, namely N,N′-diethyl-N,N′-dibutylsuccindiamide (EBSA) and N,N,N′,N′-tetrabutylsuccindiamide (TBSA), was investigated and applied to the LPE of graphite to obtain graphene. The yield of EBSA was 99.4% from succinic anhydride with a K60 silica gel catalyst under microwave conditions (160 °C in 30 min), while TBSA presented an 88.8% yield at 180 °C. The green metric demonstrated that this route has a significantly lower Process Mass Intensity (PMI) and higher Reaction Mass Efficiency (RME) values compared to previously published routes. TBSA demonstrated a ∼150% increase in the graphene and graphene oxide exfoliation (thickness <7 nm) compared to N-methylpyrrolidone (NMP). TBSA outperformed Cyrene in the LPE of graphene oxide. Graphene and graphene oxide nanosheets were characterized by transmission electron microscopy (TEM), Raman spectroscopy, X-ray diffraction (XRD), and atomic force microscopy (AFM). The solvent surface tension, density, viscosity, Hansen Solubility Parameters (HSPs), and Kamlet–Abboud–Taft parameters (KATs) were investigated to determine the key parameters for exfoliation. The high dipolarity (π*) and hydrogen bond-accepting ability (β) of TBSA promoted significant graphene exfoliation, while its greater viscosity produced high-quality graphene sheets, with ID/IG ratios of 0.005 ± 0.02 for graphene flakes of <1 μm. Higher-viscosity solvents demonstrated a limited increase in the graphene concentration with longer sonication, but retained high-quality graphene. TBSA is a potentially greener alternative to NMP for LPE, leading to opportunities for sustainable graphene production.

A series of air-stable nickel(II) complexes with various tetradentate diamino-bis(phenol)/(phenolate) ligands and coligands were synthesized. Six of these Ni[O2NN′] complexes were structurally characterized by single-crystal X-ray diffraction. The Ni[O2NN′] complexes were screened as catalysts for ring-opening copolymerization (ROCOP) of cyclohexene oxide (CHO) and phthalic anhydride (PA), utilizing bis(triphenylphosphine)iminium chloride (PPNCl) as a cocatalyst. It was determined that the catalytic activity for the Ni[O2NN′] complexes depended primarily on the coordinating coligands/counterions and the presence of a cocatalyst. Ni[O2NN′] complexes with acetate or chloride coligands selectively formed high molar mass polyesters with narrow dispersities (e.g. Mn = 14.5 kg mol–1 and Đ = Mw/Mn = 1.17), but only in the presence of the PPNCl cocatalyst. Ni[O2NN′] complexes with perchlorate counterions formed polymers containing a mixture of ester and ether linkages in the presence of PPNCl cocatalyst, and instead selectively formed polyether when no cocatalyst was used.

Multimetallic zinc, magnesium and potassium complexes of amino-bis(phenolate) ligands catalyze ring-opening polymerization of rac -lactide and ring-opening copolymerization of cyclohexene oxide and phthalic anhydride.

A series of air-stable nickel(II) complexes with various tetradentate diaminobis(phenol)/(phenolate) ligands and coligands were synthesized. Six of these Ni[O2NN¢] complexes were structurally characterized by single-crystal X-ray diffraction. The Ni[O2NN¢] complexes were screened as catalysts for ring-opening copolymerization (ROCOP) of cyclohexene oxide (CHO) and phthalic anhydride (PA) utilizing bis(triphenylphosphine)iminium chloride (PPNCl) as a cocatalyst. It was determined that the catalytic activity for the Ni[O2NN¢] complexes depended primarily on the coordinating coligands/counterions and the presence of a cocatalyst. Ni[O2NN¢] complexes with acetate or chloride coligands selectively formed high molar mass polyesters with narrow dispersities (e.g. Mn = 14.5 kg mol−1 and Đ = Mw/Mn = 1.17), but only in the presence of the PPNCl cocatalyst. Ni[O2NN¢] complexes with perchlorate counterions formed polymers containing a mixture of ester and ether linkages in the presence of PPNCl cocatalyst, and instead selectively formed polyether when no cocatalyst was used.

The synthesis and structural characterization of multinuclear complexes containing aminobis(phenolate) ligands with zinc and magnesium centres are reported. Trimetallic zinc complex Zn ₂ (Zn(OAc) ₂ ) [L] ₂ ( 1 ) (where [L] = dimethylaminoethylamino-N,N-bis(2-methylene-4-methyl-6methoxyphenolate)) was reacted with magnesium acetate in methanol to form a heterometallic complex, Zn ₂ (Mg(OAc) ₂ ) [L] ₂ with different levels of occupancy at the central metal site depending on the reaction conditions used. Addition of methanolic solutions of Mg(OAc) ₂ at –78 °C and warming to room temperature gave a complex with 74% of the central zinc positions replaced with magnesium ( 2 ). Heating the methanolic solution to reflux resulted in a higher displacement of the central zinc positions, giving 94% occupancy of the central metal site by magnesium ( 3 ). A multimetallic complex containing three Zn(II) centres and four K(I) centres, two L ligands, and six acetate co-ligands, {[LZn(OAc)] ₂ Zn(KOAc) ₄ } ( 4 ), was also synthesized and characterized. Complexes 1 and 3 catalyze the ring-opening polymerization (ROP) of rac -lactide ( rac -LA), giving polyesters with and without the presence of benzyl alcohol (BnOH) as a cocatalyst. Complexes 1 and 3 also catalyze ring-opening copolymerization (ROCOP) of cyclohexene oxide (CHO) and phthalic anhydride (PA), giving moderate molar mass polymers with narrow dispersities.

A series of air-stable nickel(II) complexes with various tetradentate diaminobis(phenol)/(phenolate) ligands and coligands were synthesized. Six of these Ni[O2NN¢] complexes were structurally characterized by single-crystal X-ray diffraction. The Ni[O2NN¢] complexes were screened as catalysts for ring-opening copolymerization (ROCOP) of cyclohexene oxide (CHO) and phthalic anhydride (PA) utilizing bis(triphenylphosphine)iminium chloride (PPNCl) as a cocatalyst. It was determined that the catalytic activity for the Ni[O2NN¢] complexes depended primarily on the coordinating coligands/counterions and the presence of a cocatalyst. Ni[O2NN¢] complexes with acetate or chloride coligands selectively formed high molar mass polyesters with narrow dispersities (e.g. Mn = 14.5 kg mol−1 and Đ = Mw/Mn = 1.17), but only in the presence of the PPNCl cocatalyst. Ni[O2NN¢] complexes with perchlorate counterions formed polymers containing a mixture of ester and ether linkages in the presence of PPNCl cocatalyst, and instead selectively formed polyether when no cocatalyst was used.