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The screen‐printing process of conductive ink can realize simple and large‐scale manufacture of micro/nano patterns for producing wearable electronic products. Herein, chitin nanocrystals (ChNCs) are used as a dispersant for the preparation of multiwalled carbon nanotube (MWCNT) ink with high viscosity and uniformity by ultrasound treatment. ChNCs can interact with MWCNT in noncovalent ways, including π–π and hydrophobic interactions. ChNCs/MWCNT (CCNT) ink does not aggregate even after standing for 3 months with a maximum MWCNT concentration of 33 mg mL−1 and dispersion efficiency of 91.1%. Using CCNT ink, a paper‐based thermoelectric generator (TEG) is manufactured by screen‐printing technology. With good thermoelectric and strain sensing properties, CCNT coated paper can stably collect human energy at room temperature to realize self‐powering. The CCNT coated paper‐based TEG can convert thermal voltage signals into musical notes, monitor the changes in human behavior and respiratory rate, and monitor joint movements. Moreover, CCNT coated paper has no cytotoxicity by CCK‐8 and live/dead staining. This work puts forward a strategy of green preparation of MWCNT‐based ink by adding renewable chitin, which opens up a new way to apply MWCNT‐based ink in self‐powering wearable multifunctional sensors. [ABSTRACT FROM AUTHOR]

To improve the mechanical, crystallization performances of poly(l‐lactide) (PLLA), pristine and surface grafted chitin whiskers (CWs and g‐CWs) were introduced to PLLA via melt blending. Attributed to the good interfacial compatibility between the g‐CWs and PLLA matrix, the tensile, flexural, and impact performances of the g‐CWs/PLLA composites were better than that of the CWs/PLLA composites with the same whiskers content. The whiskers acted as nucleating agents to promote the crystallization of the PLLA matrix on the one hand, and acted as obstacles to restrict the crystals growth on the other hand. The nonisothermal cold crystallization kinetics revealed that the crystallization rate and crystallinity of the PLLA matrix were improved by the addition of the whiskers, but the promotion effect of g‐CWs was more obvious than CWs. [ABSTRACT FROM AUTHOR]

Poly(L‐lactide) (PLLA) composites containing various content of MgO whiskers (MgO‐Ws) and surface grafted MgO whiskers (g‐MgO‐Ws) were prepared by injection molding technique. The g‐MgO‐Ws showed better dispersion in the matrix and improved interface compatibility with the matrix compared with the MgO‐Ws, which was confirmed by field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The results of differential scanning calorimeter (DSC) and polarized optical microscopy (POM) of the MgO‐Ws/PLLA and g‐MgO‐Ws/PLLA composites revealed that the crystallization rate and crystallinity of PLLA were improved by the introduction of MgO‐Ws and g‐MgO‐Ws, but the thermogravimetric measurements showed that the thermal stability of the PLLA matrix decreased by the addition of the whiskers. The tensile, flexural, and impact properties of the resulting composites were systematically studied, and the g‐MgO‐Ws/PLLA composite exhibited remarkably higher tensile strength, modulus, and toughness than those of the pure PLLA and MgO‐Ws/PLLA composite. The highest tensile strength of 62.9 ± 3.2 MPa, tensile modulus of 1,222.3 ± 25.2 MPa, and fracture energy of 459.1 ± 24.3 J/m2 were obtained for the g‐MgO‐Ws/PLLA composite with 2.5% whiskers content, which were 30.8%, 13.7%, and 105.5% higher than those of PLLA matrix, respectively. Loading the whiskers with appropriate content can also improve the flexural and impact properties of the PLLA matrix. The highest impact strength, flexural modulus, and flexural strength were obtained for the g‐MgO‐Ws/PLLA composite with 1% whiskers content. POLYM. COMPOS., 39:E1807–E1820, 2018. © 2018 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

ABSTRACT To improve the interfacial bonding between halloysite nanotubes (HNTs) and poly( l-lactide) (PLLA), a simple surface modification of HNTs with l-lactic acid via direct condensation polymerization has been developed. Two modified HNTs were obtained: HNTs grafting with l-lactic acid ( l-HNTs) and HNTs grafting with poly( l-lactide) ( p-HNTs). The structures and properties of l-HNTs and p-HNTs were investigated. Then, a series of HNTs/PLLA, l-HNTs/PLLA and p-HNTs/PLLA composites were prepared using a solution casting method and were characterized by polarized optical microscopy (POM), field scanning electron microscopy, and tensile testing. Results showed that l-lactic acid and PLLA could be easily grafted onto the surface of HNTs by forming an Al carboxylate bond and following with condensation polymerization, and the amounts of the l-lactic acid and PLLA grafted on the surface of the HNTs were 5.08 and 14.47%, respectively. The surface-grafted l-lactic acid and PLLA played the important role in improving the interfacial bonding between the nanotubes and matrix. The l-HNTs and p-HNTs can disperse more uniformly in and show better compatibility with the PLLA matrix than untreated HNTs. As a result, the l-HNTs/PLLA and p-HNTs/PLLA composites had better tensile properties than that of the HNTs/PLLA composites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41451. [ABSTRACT FROM AUTHOR]

Hydroxyethyl chitosan (HECS) was first prepared by the reaction of 2-chloroethanol with chitosan (CS). Then, CS- g-poly( D,L-lactide) (PDLLA) copolymers were synthesized through the ring-opening polymerization of D,L-lactide with CS and HECS as the macroinitiators, respectively, under microwave irradiation. The optimal synthesis conditions obtained by an orthogonal experiment were as follows: microwave power = 10 W, temperature = 130°C, irradiation time = 15 min, and catalyst concentration = 0.05 mol %. The reactivity of CS was improved by hydroxyethylation, which contributed to a higher percentage of grafting. Compared with the conventional thermal polymerization, the microwave polymerization method showed a significantly higher polymerization rate and improved efficiency. An enhanced percentage of grafting ranging from 236.25 to 317.50%, and an average degree of polymerization of PDLLA side chains ranging from 13.25 to 24.17 were achieved under microwave irradiation when the value of n D,L-lactide/ nminoglucoside units was increased from 20 : 1 to 40 : 1. The higher percentage of grafting facilitated decreases in the crystallinity and thermal stability of the copolymers, which were attributed to the weakening intramolecular and intermolecular hydrogen bonds of CS. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 [ABSTRACT FROM AUTHOR]