Poly(lactic acid)‐based nanocomposites filled with cellulose nanocrystals with modified surface: all‐atom molecular dynamics simulations

Glova, Artyom D.; Falkovich, Stanislav G.; Larin, Sergey V.; Mezhenskaya, Daria; Lukasheva, N. V.; Nazarychev, Victor M.; Tolmachev, Dmitry; Mercurieva, Anna A.; Kenny, J. M.; Lyulin, Sergey V.

doi:10.1002/pi.5102

Cited by 32 publications

(44 citation statements)

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“…Following our previous simulations [18][19][20][21], we performed atomistic molecular dynamics simulations of polylactide-based nanocomposites filled with surface-modified cellulose nanocrystals (CNC). The simulated systems comprised 20 free lactide chains that surrounded the filler, with the length of the free chains equal to 150.…”

Section: Model and Simulation Methodsmentioning

confidence: 99%

“…In our previous studies, the unusual behavior of the grafted lactide chains was observed by using atomistic molecular dynamics (MD) simulation when attempting to reproduce the known influence of the grafting density on the grafted layer structures [18,19]. Despite their dipolar nature, the lactide chains, being aliphatic ester chains, may initially seem to be the conventional grafts that were considered earlier [10][11][12][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

“…Despite their dipolar nature, the lactide chains, being aliphatic ester chains, may initially seem to be the conventional grafts that were considered earlier [10][11][12][15][16][17]. A separation of the grafted lactide chains into two populations was observed in the melt of the chemically similar polymer, although only a strong stretching of the grafts was expected [18,19]. Importantly, the segregation was found to be particularly pronounced in the "dry brush" regime [19].…”

Section: Introductionmentioning

confidence: 99%

“…The present study, however, was devoted to composites filled with surface modified 128 cellulose nanocrystals. The PLAFF3 force field [24], specifically developed for lactide chains on the In contrast to our previous studies, for the present work, the GAFF force field [23] was employed to describe the bonded and non-bonded interactions in the simulated composites [18][19][20][21]. The use of this force field for the simulations of lactide chains was validated in reference [22] on the basis of calculations for the chain's flexibility and the glass transition temperature for the corresponding bulk system.…”

mentioning

confidence: 99%

“…The present study, however, was devoted to composites filled with surface modified cellulose nanocrystals. The PLAFF3 force field [24], specifically developed for lactide chains on the basis of the OPLS force field [25], has been previously used for these systems [18][19][20][21]. It was necessary to implement additional interaction parameters from the OPLS force field that described pristine and modified cellulose chains in order to simulate the required composites.…”

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confidence: 99%

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Grafting-Induced Structural Ordering of Lactide Chains

et al. 2019

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The structure of a grafted layer of lactide chains in the "dry brush" regime immersed in a melt of chemically similar polymer was examined while varying graft lengths. To this end, microsecond atomistic molecular dynamics simulations were performed. Almost no influence of graft length on the fraction of the grafted chains backfolded to the grafting surface was found. However, a structural ordering was unexpectedly observed in the system when the length of the grafted lactide chains was close to approximately 10 Kuhn segments. This ordering of the grafts is characterized by the formation of helical fragments whose structure is in good agreement with the experimental data for the α crystal of the lactide chains. Both the backfolding and the structural ordering may be viewed as the initial stage of the crystallization of the layer of grafted lactide chains. In contrast to the known behavior for conventional polymer brushes in the "dry brush" regime, the structure of the grafted lactide chains can be either amorphous or ordered, depending on the graft length N and the grafting density σ when their product Nσ is fixed.of the grafts into populations of backfolded and stretched chains was most pronounced at this σ in 96 comparison with the other grafting densities [19,20]. Having fixed σ, the length of the grafted chains 97 N was varied. Six lengths of the grafted chains, N = 13, 17, 22, 30, 40 and 50, were examined. Snapshots 98 of the systems in the case of N = 13 and 50 are presented in Figure 1. Additionally, a grafted layer in 99 the "dry brush" regime with the grafting density σ = 0.88 nm −2 and the graft length N = 60 was 100 simulated. This system was compared with the one where the grafting density σ = 1.76 nm −2 and the 101 graft length N = 30 in order to examine difference in the structure between the two grafted layers at 102 a fixed product of Nσ. According to our previous estimate of the characteristic ratio [22], the Kuhn 103 segment length A for the lactide chains is equal to approximately 1.6 nm. The contour length L of the 104 grafts under consideration could be calculated as  L aN , where a = 0.38 nm was the contour length 105 of the monomer in the graft. These calculations gave contour lengths L in the range 5-19 nm for the 106 considered length of the grafts at σ = 1.76 nm −2 . Thus, the number of Kuhn segments in the grafts at 107 this σ varied from approximately 3 to 12 units, lying in different orders of magnitude. For the grafts 108 where σ = 0.88 nm −2 , the contour length and the number of Kuhn segments were equal to about 23 nm 109 and 14 units, respectively. The chosen graft lengths were limited by the computational demands 110 required to perform simulations of the corresponding composites. To the best of our knowledge, the 111 considered grafts were among the longest ever studied by using atomistic molecular dynamics 112 simulations. In the present study, the total number of atoms in the system with the grafted layer at 113 σ = 1.76 nm −2 and N = 13 was about 53,000, while the composite c...

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Section: Model and Simulation Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

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Grafting-Induced Structural Ordering of Lactide Chains

et al. 2019

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Special Issue: BIOPOL 2015

Jiménez

Eceiza

Kenny

2016

Polymer International

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Polyhydroxybutyrate: a review of experimental and simulation studies of the effect of fillers on crystallinity and mechanical properties

Majerczak

Wadkin-Snaith

Magueijo

et al. 2022

Polymer International

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Polyhydroxybutyrate (PHB) is a sustainable polymer that is a promising candidate for replacing petroleum-based plastics in food packaging. Fillers are used to improve the mechanical properties of PHB composites, simultaneously changing the crystallinity of the polymer matrix. However, it is not well understood how fillers affect crystallisation and microstructure, and thus the resulting mechanical properties of the composite. This review summarises simulation work on polymer nucleation and crystallisation and how nucleation is influenced by different types of polymer-filler interfaces. Experimental studies of PHB composites with a wide variety of fillers are reviewed to find trends between the filler type, crystallinity and mechanical properties. It is clear that fillers act as nucleants that increase the number of spherulites while reducing spherulite size. This behaviour is apparent for almost all fillers regardless of filler chemistry or topology. However, the data obtained from the literature do not seem to produce strong conclusions about the effect of the degree of crystallinity on the tensile properties of PHB-filler composites, although there are some weak trends that indicate the importance of microstructure. In order to enable prediction and control of PHB composite properties, further systematic studies are required to elucidate the effect of specific filler types and the connection between crystallinity, microstructure and mechanical properties.

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Poly(lactic acid)‐based nanocomposites filled with cellulose nanocrystals with modified surface: all‐atom molecular dynamics simulations

Cited by 32 publications

References 64 publications

Grafting-Induced Structural Ordering of Lactide Chains

Grafting-Induced Structural Ordering of Lactide Chains

Special Issue: BIOPOL 2015

Polyhydroxybutyrate: a review of experimental and simulation studies of the effect of fillers on crystallinity and mechanical properties

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