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The plastics structure-property correspondence has been conventionally identified through either forward discovery chemistry approach or reverse analysis physics approach. The viewing of each monomer unit as a non-divisible entity limits these approaches as an inherently non-programmable tool. Herein, molecular plastics programming is reported as a...
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... CC BY-NC-ND 4.0 side extended by an ethylester spacer and a varied-length alkyl moiety, and capped with a reactive olefin closing group. The ring-opening metathesis polymerization (ROMP) leads to the generation of a polymer with a desired integration of building blocks for each monomer unit (herein, a building block refers to a partitioned, continuous molecular segment within a monomer): a rigid building block (most rigid molecular segment; squaramide), a flexible building block (most flexible molecular segment; alkyl moiety), an effective main-chain rigid-flexible-chain-dynamics spacer coupling building block (neither most rigid nor most flexible molecular segment, in between the rigid and flexible building blocks; ethylester), and a linker building block (neither most rigid nor most flexible molecular segment, not in between the rigid and flexible building blocks; alkene moiety) ( Figure 1). The rigid building block offers high segmental (packing) stiffness and low segmental mobility through both electronic aromatization and hydrogen bonding and is beneficial for strengthening the elastic deformation. ...
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... commence our investigation by the cost-effective and expedient synthesis of product with in general, an over-85% yield, an above-40k molecular weight, and a relatively low polydispersity (isolated product yield, Mn, Đ: P1, 86%, 44.7k, 1.51; P2, 89%, 43.3k, 1.42; P3, 87%, 46.3k, 1.31; P4, 87%, no measurable Mn, Đ due to the low solubility) (Table 1, Figure S1). The glass transition temperature (Tg: P1, 46. ...
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... glass transition temperature (Tg: P1, 46. ): whereas no crystallization can be discerned for short-segmented P1 and P2, partial crystallization is observed for long-segmented P3 (melting temperature, or Tm: 118 stress-strain curves of P1-P4, ref. to Figure 3). For the elastic region, the Young's modulus (P1, 521.8 MPa; P2, 369.7 MPa; P3, 231.8 MPa; P4, 207.8 MPa) (Table 2) observations relevant to the mechanical deformation are noteworthy: α-relaxation The main-chain rigid-flexible-building-block coupling is central to the achievement of high chain mobility and high ductility under mechanical deformation. ...
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... one set of experiments, two otherwise identical polymers in reference to P2 except with the replacement of squaramide by 1,4-phenylene (P5, 89%, 66.7k, 1.45) and butane-1,4-diyl (P6, 86%, 77.2k, 1.53) ( Figure S9 bonding as a source of rigidity in P2 (Table 3, Table 4, Figure 6). In contrast, a fully Nmethylated variant of P2, P7 (85%, 53.2k, 1.66) ( Figure S9), only witnesses a modest drop in T g (-3.8 o C) ( Figure S10), suggesting squaramide, even without the contribution of hydrogen bonding, as a more rigid building block than 1,4-phenylene. P5 is amorphous and extremely soft (for stress-strain curves of P5-P12, ref. to Figure 7), and P6 is semicrystalline (T m : 36.9 o C) and moderately ductile (18.6 MJ/m 3 ) (Table S1). ...
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... Polymer main-chain rigid-flexible-building-block coupling and main-chainside-chain flexible-rigid-building-block coupling are comparably effective for a scalar field (e.g., thermal) activation, whereas main-chain rigid-flexible-building-block coupling is more effective than main-chain-side-chain flexible-rigid-building-block coupling for a vector field (e.g., mechanical) activation ( main-chain building block and side-chain building block is dependent on structural context and should be defined through the systematic exploration and precise dissection of the role associated with each building block. Symmetry can be a dictating factor in this building block-defining process; for example, symmetrically structured propane-2,2-diyl in PC, even though seemingly spanning both main and side chain, is defined as a main-chain building block as it acts as a continuous, coherent whole flexible entity, whereas asymmetrically structured ethane-1,1,2-triyl and methyl in PMMA are defined as one main-chain building block and one side-chain building block as methyl is a distinct entity imparting rigidity to ethane-1,1,2-triyl ( Figure 10). Once a comprehensive pool of well-defined building blocks has been established, it can be used as a predictive knowledge base for molecular plastics programming ( Figure 11 non-collective, non-cooperative (more discrete) chain mobility actuation (nonconstrained, easy actuation) and therefore a gentle strain softening behavior (e.g., P3 ...
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... can be a dictating factor in this building block-defining process; for example, symmetrically structured propane-2,2-diyl in PC, even though seemingly spanning both main and side chain, is defined as a main-chain building block as it acts as a continuous, coherent whole flexible entity, whereas asymmetrically structured ethane-1,1,2-triyl and methyl in PMMA are defined as one main-chain building block and one side-chain building block as methyl is a distinct entity imparting rigidity to ethane-1,1,2-triyl ( Figure 10). Once a comprehensive pool of well-defined building blocks has been established, it can be used as a predictive knowledge base for molecular plastics programming ( Figure 11 non-collective, non-cooperative (more discrete) chain mobility actuation (nonconstrained, easy actuation) and therefore a gentle strain softening behavior (e.g., P3 ...
