C-enrichment of furan by custom synthesis followed by modest-pressure synthesis of 13 C-enriched nanothreads enabled a detailed characterization of the reaction products by a full complement of advanced solid-state NMR techniques, with validation by ab initio calculation of chemical shifts. The 13 C NMR spectrum was complex, with more than a dozen distinct features, but almost all (> 95%) represented CH moieties are as expected in nanothreads, with only 2-4% CH 2 , 0.3% C=O, and 0.3% COO groups, according to spectral editing. Different components were quantified by integration of the fully equilibrated direct-polarization spectrum. Symmetric and asymmetric alkene-containing rings as well as trapped furan were identified by 13 C-13 C and 1 H-13 C NMR. The most intriguing component observed was fully saturated perfect anti furan-derived nanothread segments, with two distinct, sharp peaks, accounting for ca. 10% of the material.The bonding patterns in these periodic structures deduced from DQ/SQ NMR was that of a [4+2] cycloaddition product. While the small number of chemically inequivalent carbon sites eliminated low-symmetry syn/anti threads, the large number of magnetically inequivalent ones (i.e., distinct C-H orientations) in CODEX NMR was incompatible with the high-symmetry syn threads. Anti threads with two chemically and eight magnetically inequivalent sites provide the only consistent fit of the experimental data.These conclusions were convincingly corroborated by quantum-chemical simulations, which showed good agreement of isotropic chemical shifts only for the anti threads. This represents the first molecular-level identification of a specific type of nanothread. The typical length of the perfect, fully saturated thread segments was around 14 bonds and they accordingly constitute small clusters (according to 13 C and 1 H spin diffusion analyses) which likely reside within an overall hexagonal thread packing along with other, less-perfect or less-saturated brethren. The relatively slow T 1C relaxation confirms the nanometer-scale length of the periodic perfect structure, indicates that the perfect threads are particularly rigid, and enables their selective observation in 13 C NMR.

Chain-level structure of semicrystalline polymers in melt- and solution-grown crystals has been debated over the past several decades. Recently, 13C–13C double quantum (DQ) NMR spectroscopy and spin-dynamics simulation have been applied to trace chain trajectory and packing structure of 13C labeled polymers in melt- and solution-grown crystals. We highlight recent NMR studies for (i) packing structure, (ii) chain trajectory, (iii) conformation of the folded chains, (iv) nucleation mechanisms in the early stage of crystallization, and (v) deformation mechanism at the molecular scale of semicrystalline polymers.

In this work, mechanochemical pretreatment of Bambusa vulgaris is evaluated for waste‐free production of renewable sugars for subsequent fermentation. After a 60 min mechanochemical pretreatment followed by enzyme hydrolysis at 50 °C, 62% of the available carbohydrate can be recovered as fermentable sugars, primarily in the form of glucose and xylose. Structural and chemical analysis finds that mechanochemical pretreatment increases accessible surface area and amorphizes the crystalline cellulose present in bamboo, both of which increase reactivity. The experimental results are then used for a systems‐level analysis of ethanol production in Nigeria. The energy required for mechanochemical pretreatment is estimated to be 0.5–5.6 MJ per kg of bamboo; this energy can be provided by solar power, while still satisfying existing needs for stationary power. Ethanol production on marginal land alone is projected to be sufficient to replace nearly 80% of Nigeria's current gasoline usage while reserving sufficient land area for solar power generation to meet current electricity needs, meaning that bamboo cultivation followed by mechanochemical pretreatment can play an important role for utilizing locally available resources without generation of new chemical wastes.

Low- and middle-income countries have tremendous potential for renewable energy production, including production of renewable carbon from locally prolific crops. In this work, bamboo endemic to West Africa (Bambusa vulgaris) was studied as a feedstock for the production of renewable sugars as the gateway to the local production of biofuels and bio-based chemical products. The effectiveness of delignification and amorphization pretreatments was evaluated, with the observation that quantitative (97 ± 4%) sugar yields could be obtained with a rapid initial hydrolysis rate (82 ± 4 mg g−1 h−1) but only when amorphization was performed following delignification. Experimental measurements and further characterization using 13C solid state nuclear magnetic resonance (NMR) helped establish the importance of amorphization and delignification and explained why the order of these treatments determined their effectiveness. The economics of the bamboo-based process were compared with those projected for corn stover, selected as a well-studied benchmark crop. Because of the higher bamboo growth rate compared with corn stover and the effectiveness of the pretreatment, the projected net present value (NPV) of the bamboo biorefinery was positive ($190 MM, U.S.), whereas the corn biorefinery projected to negative NPV (−$430 MM, U.S.). A socially sustainable framework for deployment of a bamboo biorefinery in a low- or middle-income economy was then proposed, guided by the principle of local ownership and stakeholder buy-in. The findings presented here motivate further investment in development of bamboo cultivation and conversion to sugars as a rapid route to decarbonization of low- and middle-income economies.

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