Janus nanoparticles, methods of making the same, and biobased polyester compositions made therefrom

Abstract

The application discloses a kind of Janus nanoparticles, its preparation method includes the following steps: (1) polypropylene carbonate diol (PPCD) is reacted with lysine diisocyanate, after reaction, TiO2 Hollow sphere dispersion is added in system, and TiO2 Hollow sphere of outer surface grafting PPCD is prepared;(2) after ultrasonic fragmentation, TiO2-PPCD nanoparticle is obtained, and then is reacted with silane coupling agent, poly-D-lactic acid (PDLA), and the Janus nanoparticle is prepared.The application is used to prepare biobased polyester composition, including the following weight parts of raw materials: polypropylene carbonate 60-90 parts, poly-D-lactic acid 10-40 parts, Janus nanoparticle 0.1-3 parts.The nanoparticle of the application effectively improves the compatibilization efficiency of the composition, and the tensile strength and elongation at break are also improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of functional materials, in particular to a Janus nanoparticle and a preparation method and a prepared bio-based polyester composition thereof. BACKGROUND

[0002] With the continuous progress of science and technology, single-component polymers are difficult to meet the requirements of industrial production and life. Polymer blends can integrate the advantages of single polymers and effectively solve this problem, so the development of polymer blending technology is particularly important. However, many polymer blends are incompatible, and their components exhibit large interfacial tension, resulting in rough phase structures and poor mechanical properties of these blends, so it is particularly important to improve the compatibility of the blends. The most optimal choice to improve the compatibility of polymers at present is to add a compatibilizer. With the development of compatibilization technology, people have put forward higher requirements for improving the compatibility of polymers. In addition to improving the compatibilization efficiency, multifunctionality is also introduced to expand its application in the field of materials.

[0003] Adding a compatibilizer is a relatively simple and efficient method for improving the compatibility of blended materials. Polypropylene carbonate PPC is a new type of biodegradable aliphatic biopolymer, which has good degradation performance, barrier performance, temperature sensitivity, and transparency, non-toxicity, and other characteristics, and has good application prospects in the fields of food packaging, medical materials, engineering plastics, adhesives, etc. Poly(lactic acid) PLA is a new type of biodegradable material, which has good processing performance and can be applied in multiple fields such as extrusion, injection molding, film drawing, and spinning. However, the compatibility of the two is poor, and the blended material exhibits poor processing performance. Common compatibilizers include block copolymers and graft copolymers, but their compatibilization efficiency is low, and they do not have other functionalities, which cannot meet the needs of processing materials. SUMMARY

[0004] In view of the above problems existing in the prior art, the present application provides a Janus nanoparticle and a preparation method and a prepared bio-based polyester composition thereof. In the present application, TiO2 hollow spheres are modified as templates to prepare PPCD / PDLA Janus nanoparticles, which can be better dispersed at the interface of the two phases when added to the base PPC / PLLA, thereby effectively improving the compatibilization efficiency of the blend. At the same time, the tensile strength and elongation at break of the blend are improved, and due to the characteristics of the TiO2 template, the blend also has certain ultraviolet resistance, effectively widening the application field of the blend.

[0005] The technical scheme of the present application is as follows:

[0006] The first object of the present application is to provide a Janus nanoparticle which is templated by a TiO2 hollow sphere and has polypropylene carbonate diol and dextro-poly-lactic acid respectively modified on two sides of the template.

[0007] The second object of the present application is to provide a preparation method of the Janus nanoparticle, comprising the following steps:

[0008] (1) polypropylene carbonate diol (PPCD) is reacted with lysine diisocyanate, after the reaction is completed, a TiO2 hollow sphere dispersion liquid is added into the system to prepare a TiO2 hollow sphere with PCCD grafted on the outer surface;

[0009] (2) the TiO2 hollow sphere with PCCD grafted on the outer surface is broken by ultrasonic to obtain a TiO2-PPCD nanoparticle, and then the nanoparticle is reacted with a silane coupling agent and dextro-poly-lactic acid (PDLA) to prepare the Janus nanoparticle.

[0010] In an embodiment of the present application, in step (1), the molar ratio of the PPCD to the lysine diisocyanate is 1:2-3.5.

[0011] In an embodiment of the present application, the specific reaction process is as follows: the PPCD is dropped into the lysine diisocyanate, a catalyst dibutyl tin dilaurate (added in an amount of 0.01-0.05% of the mass of the PPCD) is added, and the reaction is stirred at 60°C for 2h under the condition of nitrogen; then, the TiO2 hollow sphere dispersion liquid is added into the reaction system, and the temperature is lowered to 40°C for stirring for 12h; and then the TiO2 hollow sphere with PCCD grafted on the outer surface is prepared by washing with tetrahydrofuran and anhydrous ethanol, and centrifugation and drying.

[0012] In an embodiment of the present application, in step (1), the TiO2 hollow sphere dispersion liquid is prepared by dispersing TiO2 hollow spheres in anhydrous ethanol; and the concentration of the TiO2 hollow sphere dispersion liquid is 1-1.5g / 100ml.

[0013] In an embodiment of the present application, in step (1), the mass-volume ratio of the PPCD to the TiO2 hollow sphere dispersion liquid is 0.3-0.5 / 100, g / ml.

[0014] In an embodiment of the present application, in step (1), the specific method is as follows: 100ml of the TiO2 hollow sphere dispersion liquid is added into the product of the polyurethane reaction, and the reaction is carried out in a three-necked flask (under the condition of nitrogen) at 40°C for 12h; and then the TiO2 hollow sphere with PCCD grafted on the outer surface is obtained by centrifugal washing with tetrahydrofuran and anhydrous ethanol, and drying.

[0015] In one embodiment of the present application, in step (2), the TiO2 hollow spheres grafted with PPD are dispersed in anhydrous ethanol, and the hollow spheres are broken into pieces, i.e., TiO2-PPCD nanoparticles, by ultrasonic treatment at 500 W for 1 h.

[0016] In one embodiment of the present application, in step (2), the silane coupling agent is KH560; and the mass ratio of TiO2-PPCD nanoparticles, poly-L-lactic acid and the silane coupling agent is 1:2-5:5-10.

[0017] In one embodiment of the present application, in step (2), the reaction is carried out at 120℃ for 20-25 h in nitrogen; and then the free PDLA is removed by washing with chloroform and centrifugation to obtain the final Janus nanoparticles.

[0018] In one embodiment of the present application, the TiO2-PPCD nanoparticles are dispersed in anhydrous ethanol, then the silane coupling agent KH560 is added to graft epoxy groups on the surface of the nanoparticles, and then poly-L-lactic acid PDLA is added to react with the epoxy groups, and finally the Janus nanoparticles are obtained by sufficient stirring, centrifugation and drying.

[0019] In one embodiment of the present application, the ultrasonic power is 400-600 W, preferably 500 W, and the ultrasonic time is 1-2 h.

[0020] In one embodiment of the present application, the KH560 is added to anhydrous ethanol for alcoholysis, and the temperature is raised to 40℃, and the reaction is carried out for 1-1.5 h.

[0021] In one embodiment of the present application, the mass ratio of TiO2-PPCD nanoparticles and the silane coupling agent is 1:5-10; preferably 1:7-8.

[0022] A third object of the present application is to provide an application of the Janus nanoparticles to the preparation of a bio-based polyester composition.

[0023] A fourth object of the present application is to provide a bio-based polyester composition comprising Janus nanoparticles, which comprises the following raw materials in parts by weight: 60-90 parts of polypropylene carbonate, 10-40 parts of poly-L-lactic acid and 0.1-3 parts of Janus nanoparticles.

[0024] In one embodiment of the present application, the bio-based polyester composition comprises the following raw materials in parts by weight: 70 parts of polypropylene carbonate, 30 parts of poly-L-lactic acid and 0.3 parts of Janus nanoparticles.

[0025] In one embodiment of the present application, the bio-based polyester composition comprises the following raw materials in parts by weight: 60 parts of polypropylene carbonate, 40 parts of poly-L-lactic acid and 0.5 parts of Janus nanoparticles.

[0026] A fifth object of the present application is to provide a bio-based polyester material containing Janus nanoparticles, wherein 60-90 parts of polypropylene carbonate, 10-40 parts of poly-L-lactic acid, and 0.1-3 parts of Janus nanoparticles are melt blended, and then molded to obtain the bio-based polyester material.

[0027] In one embodiment of the present application, melt blending is performed at 170-190°C by a torque rheometer.

[0028] In one embodiment of the present application, melt blending is performed at 180°C by a torque rheometer.

[0029] During melt blending, entanglement of molecular chains occurs, and grafted PDLA and the matrix PLLA form a stereocomplex structure during melt blending.

[0030] A fifth object of the present application is to provide an application of Janus nanoparticles or a bio-based polyester composition or a bio-based polyester material in the fields of food packaging, agriculture, or aerospace.

[0031] The present application has the beneficial technical effects of:

[0032] (1) The present application obtains a strong and tough bio-based polyester composition by synthesizing Janus nanoparticles, and can prepare a film material, while improving the tensile strength, elongation at break, and other physical and mechanical properties of polypropylene carbonate material.

[0033] (2) The present application designs a Janus structure, adjusts the morphology of its distribution, and prepares a bio-based polyester composition with high transparency, which is beneficial to the expansion of its application in the packaging field.

[0034] (3) The present application can significantly improve the interfacial interaction force between PPC and PLLA by adding reactive compatibilizer Janus nanoparticles, reduce the average size of the dispersed phase, and make the dispersed phase have better toughening or other modification effects. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 The infrared spectrum of the Janus nanoparticles obtained in Example 1.

[0036] Figure 2 The schematic diagram of Janus nanoparticles at the interface between two phases.

[0037] Figure 3 The distribution morphology of Janus nanoparticles at the interface between two phases in the film material in Application Example 1.

[0038] Figure 4 The transparency of the film material in Application Example 1. DETAILED DESCRIPTION

[0039] The application will be described in detail below with reference to the drawings and examples.

[0040] The average particle size of the TiO2 hollow microspheres selected in the embodiment of the application is 3 microns.

[0041] Figure 2 The figure is a schematic diagram of Janus nanoparticles at the interface of two phases. During melt blending, under the action of high temperature and shearing, the PPCD and PDLA molecular chains grafted on both sides of the Janus nanoparticles are entangled with the matrix, and the PDLA molecular chains form a stereocomplex structure with the PLLA of the matrix during the mixing process, so that it can be stably anchored on the interface of the two phases, which helps to reduce the interfacial tension and significantly improve the compatibilization efficiency. The compatibility between PPC and PLLA is significantly improved, and the comprehensive performance of the blend is improved.

[0042] Example 1

[0043] A preparation method of Janus nanoparticles, comprising the following steps:

[0044] (1) 47.5g PPCD as diol, distillation under reduced pressure at 110℃ for 2h, then cooled to 60℃, the distilled PPCD was dropped into 11.3g lysine diisocyanate, 0.005g of catalyst dibutyltin dilaurate was added, and the reaction was stirred at 60℃ for 2h under the condition of nitrogen; then the temperature was lowered to 40℃ and stirred for 12h; then washed with tetrahydrofuran and anhydrous ethanol, centrifuged and dried to obtain TiO2 hollow spheres grafted with PPCD on the outer surface;

[0045] (2) The TiO2 hollow spheres grafted with PPCD on the outer surface were dispersed in ethanol and treated by ultrasonic (500W) for 1h to break them into pieces to obtain TiO2-PPCD nanoparticles;

[0046] (3) 3g TiO2-PPCD nanoparticles were dispersed in anhydrous ethanol, then 15ml of silane coupling agent KH560 was added to graft epoxy groups on the surface, and then 5g of PDLA was added, and the reaction was carried out at 120℃ for 25h in a three-necked flask (nitrogen). Finally, after sufficient stirring, centrifugation, chloroform washing and drying, the Janus nanoparticles were obtained.

[0047] The KH560 is an alcoholysis product, which is added to anhydrous ethanol, and the temperature is raised to 40℃ and the reaction is carried out for 1.5h.

[0048] The infrared spectrum of the Janus particles prepared in this example is shown in Figure 1 Figure 1 ​It can be seen that the infrared curve of TiO2-PPCD nanoparticles has peaks at 1748 cm -1 and 1254 cm -1 , which are characteristic groups of PCCD, corresponding to C=O bond and C-O bond respectively, indicating that the PCCD grafting is successful. The Ti-OH group peak is significantly reduced, indicating that part of OH is consumed in the reaction, further proving the occurrence of the reaction. The infrared curve of the PPCD / PDLA Janus nanoparticles has new peaks at 2800-3000 cm -1 , which are attributed to the symmetric and asymmetric stretching vibration of C-H bond. In addition, the carbonyl peak at 1748 cm -1 is significantly enhanced, which is attributed to the carbonyl stretching vibration of PDLA chain, thereby proving the successful synthesis of PPCD / PDLA Janus nanoparticles.

[0049] Example 2

[0050] A method for preparing a Janus nanoparticle, comprising the following steps:

[0051] (1) 47.5g PPCD as diol is distilled under reduced pressure at 110℃ for 2h, then cooled to 60℃, and the distilled PPCD is added dropwise into 5.65g lysine diisocyanate, and a catalyst dibutyltin dilaurate 0.005g is added, and the reaction is stirred at 60℃ for 2h under nitrogen; then TiO2hollow sphere dispersion liquid 200ml (1.5 / 100, g / ml) is added, and the temperature is lowered to 40℃, and stirred for 12h; then washed with tetrahydrofuran and anhydrous ethanol, centrifuged and dried to obtain TiO2hollow spheres grafted with PPCD on the outer surface;

[0052] (2) The TiO2hollow spheres grafted with PPCD on the outer surface are dispersed in ethanol and treated with ultrasonic (500W) for 1h to break them into pieces to obtain TiO2-PPCD nanoparticles;

[0053] (3) 3g TiO2-PPCD nanoparticles are dispersed in anhydrous ethanol, then 15ml silane coupling agent KH560 is added to graft epoxy groups on the surface, and then 5g PDLA is added, and the reaction is carried out at 120℃ for 25h in a three-necked flask (nitrogen), and finally the Janus nanoparticles are obtained after sufficient stirring, centrifugation, chloroform washing and drying.

[0054] Example 3

[0055] A method for preparing a Janus nanoparticle, comprising the following steps:

[0056] (1) 23.75g PPCD as diol, distilled at 110°C under reduced pressure for 2h, then cooled to 60°C, the distilled PPCD was dropped into 11.3g lysine diisocyanate, catalyst dibutyltin dilaurate 0.005g was added, stirred at 60°C under nitrogen for 2h; then TiO2hollow sphere dispersion liquid 200ml (1.5 / 100, g / ml) was added, cooled to 40°C and stirred for 12h; then washed with tetrahydrofuran, anhydrous ethanol, centrifuged and dried to obtain TiO2hollow spheres grafted with PPCD on the outer surface;

[0057] (2) The TiO2-PPCD hollow spheres grafted with PPCD on the outer surface were dispersed in ethanol and treated with ultrasonic (500W) for 1h to break them into pieces to obtain TiO2-PPCD nanoparticles;

[0058] (3) 3g TiO2-PPCD nanoparticles were dispersed in anhydrous ethanol, then 15ml silane coupling agent KH560 was added to graft epoxy groups on the surface, and then 5g PDLA was added, and the mixture was reacted at 120°C in a three-necked flask (nitrogen) for 25h. Finally, the Janus nanoparticles were obtained after sufficient stirring, centrifugation, chloroform washing and drying.

[0059] Example 4

[0060] A method for preparing Janus nanoparticles, comprising the following steps:

[0061] (1) 47.5g PPCD as diol, distilled at 110°C under reduced pressure for 2h, then cooled to 60°C, the distilled PPCD was dropped into 11.3g lysine diisocyanate, catalyst dibutyltin dilaurate 0.005g was added, stirred at 60°C under nitrogen for 2h; then TiO2hollow sphere dispersion liquid 200ml (1.5 / 100, g / ml) was added, cooled to 40°C and stirred for 12h; then washed with tetrahydrofuran, anhydrous ethanol, centrifuged and dried to obtain TiO2hollow spheres grafted with PPCD on the outer surface;

[0062] (2) The TiO2-PPCD hollow spheres grafted with PPCD on the outer surface were dispersed in ethanol and treated with ultrasonic (500W) for 1h to break them into pieces to obtain TiO2-PPCD nanoparticles;

[0063] (3) 3g TiO2-PPCD nanoparticles were dispersed in anhydrous ethanol, then 15ml silane coupling agent KH560 was added to graft epoxy groups on the surface, and then 5g PDLA was added, and the mixture was reacted at 120°C in a three-necked flask (nitrogen) for 25h. Finally, the Janus nanoparticles were obtained after sufficient stirring, centrifugation, chloroform washing and drying.

[0064] Application Example 1

[0065] A tough bio-based polyester composition was prepared by adding PPC 70 parts, PLLA 30 parts, Janus nanoparticles prepared in Example 1 0.3 parts, after being fully dried, into a torque rheometer at 180℃ according to the weight ratio. Finally, a film material was obtained by a compression molding process at 190℃.

[0066] Figure 3 For the morphology of Janus nanoparticles at the interface of the film material, it can be seen that the Janus nanoparticles are anchored at the interface in a single layer state, thus playing a role of efficient compatibilization.

[0067] Figure 4 For the transparency test results of the film material prepared in this application example, compared with the film material prepared by the pure PPC / PLLA blend in Comparative Example 1, Figure 4 a), the transparency of the film material formed by the blend after adding Janus nanoparticles did not decrease significantly Figure 4 b), under the premise of not sacrificing transparency, the compatibility and comprehensive performance of the blend were significantly improved, due to the anchoring of Janus nanoplates at the interface, effective molecular chain entanglement and chemical reaction. Only adding unmodified TiO2 nanoparticles, the transparency is poor, and the comprehensive performance of the blend is also poor, due to the poor dispersibility of TiO2 nanoparticles in the blend.

[0068] Application Example 2

[0069] A tough bio-based polyester composition was prepared by adding PPC 70 parts, PLLA 30 parts, Janus nanoparticles prepared in Example 1 0.7 parts, after being fully dried, into a torque rheometer at 180℃ according to the weight ratio. Finally, a film material was obtained by a compression molding process at 190℃.

[0070] Application Example 3

[0071] A tough bio-based polyester composition was prepared by adding PPC 70 parts, PLLA 30 parts, Janus nanoparticles prepared in Example 1 1 part, after being fully dried, into a torque rheometer at 180℃ according to the weight ratio. Finally, a film material was obtained by a compression molding process at 190℃.

[0072] Application Example 4

[0073] A tough bio-based polyester composition was prepared by adding PPC 60 parts, PLLA 40 parts, Janus nanoparticles prepared in Example 1 0.3 parts, after being fully dried, into a torque rheometer at 180℃ according to the weight ratio. Finally, a film material was obtained by a compression molding process at 190℃.

[0074] Application Example 5

[0075] A tough bio-based polyester composition was prepared by adding PPC 70 parts, PLLA 30 parts, Janus nanoparticles prepared in Example 2 0.3 parts, after being dried sufficiently, into a torque rheometer at 180°C in parts by weight. Finally, a film material was obtained by a compression molding process at 190°C.

[0076] Application Example 6

[0077] A tough bio-based polyester composition was prepared by adding PPC 70 parts, PLLA 30 parts, Janus nanoparticles prepared in Example 3 0.3 parts, after being dried sufficiently, into a torque rheometer at 180°C in parts by weight. Finally, a film material was obtained by a compression molding process at 190°C.

[0078] Application Example 7

[0079] A tough bio-based polyester composition was prepared by adding PPC 70 parts, PLLA 30 parts, Janus nanoparticles prepared in Example 4 0.3 parts, after being dried sufficiently, into a torque rheometer at 180°C in parts by weight. Finally, a film material was obtained by a compression molding process at 190°C.

[0080] Comparative Example 1

[0081] Compared with Application Example 1, no Janus nanoparticles were added, and other conditions were unchanged, as follows:

[0082] A tough bio-based polyester composition was prepared by adding PPC 70 parts, PLLA 30 parts, after being dried sufficiently, into a torque rheometer at 180°C in parts by weight. Finally, a film material was obtained by a compression molding process at 190°C.

[0083] Comparative Example 2

[0084] Compared with Application Example 1, the number of parts of Janus nanoparticles was changed to 5, and other conditions were unchanged, as follows:

[0085] A tough bio-based polyester composition was prepared by adding PPC 70 parts, PLLA 30 parts, Janus nanoparticles prepared in Example 1 5 parts, after being dried sufficiently, into a torque rheometer at 180°C in parts by weight. Finally, a film material was obtained by a compression molding process at 190°C.

[0086] Comparative Example 3

[0087] Compared with Application Example 1, the number of parts of Janus nanoparticles was changed to 10, and other conditions were unchanged, as follows:

[0088] The toughened bio-based polyester composition was prepared by adding PPC 70 parts, PLLA 30 parts, Janus nanoparticles prepared in Example 1 10 parts, after being dried sufficiently, into a torque rheometer at 180℃ according to the weight ratio. Finally, the film material was obtained by a compression molding process at 190℃.

[0089] Comparative Example 4

[0090] Compared with Application Example 2, the number of Janus nanoparticles was changed to 5 parts, and other conditions were unchanged, as follows:

[0091] The toughened bio-based polyester composition was prepared by adding PPC 60 parts, PLLA 40 parts, Janus nanoparticles prepared in Example 1 5 parts, after being dried sufficiently, into a torque rheometer at 180℃ according to the weight ratio. Finally, the film material was obtained by a compression molding process at 190℃.

[0092] Comparative Example 5

[0093] Compared with Application Example 2, the processing temperature was changed to 160℃, and other conditions were unchanged, as follows:

[0094] The toughened bio-based polyester composition was prepared by adding PPC 60 parts, PLLA 40 parts, Janus nanoparticles prepared in Example 2 0.5 parts, after being dried sufficiently, into a torque rheometer at 160℃ according to the weight ratio. Finally, the film material was obtained by a compression molding process at 190℃.

[0095] Comparative Example 6

[0096] Compared with Application Example 1, PPC, PPCD, PLLA, PDLA, TiO2 hollow microspheres (pure nanoparticles, without any modification and grafting) were added together, and other conditions were unchanged, as follows:

[0097] The toughened bio-based polyester composition was prepared by adding PPC 70 parts, PLLA 30 parts, PPCD 1 part, PDLA 1 part, TiO2 hollow microspheres 0.3 parts, after being dried sufficiently, into a torque rheometer at 180℃ according to the weight ratio. Finally, the film material was obtained by a compression molding process at 190℃.

[0098] The bio-based polyester composition obtained in the above Application Examples 1-7 was dried sufficiently, and the tensile properties of the material at room temperature were tested according to the GB / T 1040 2006 standard method, with a tensile rate of 10 mm / min. At least 5 sample strips were tested for each sample, and the average value was taken. The PLLA phase size was counted under a magnification of 5000 by SEM after liquid nitrogen brittle fracture. The ultraviolet protection factor (UPF) was calculated according to the ultraviolet transmittance of the bio-based polyester composition in the range of 290 nm-400 nm. The results are shown in Table 1.

[0099] Table 1

[0100] Application Example Breaking strength (MPa) Breaking elongation (%) PLLA phase size (pm) UPF Application Example 1 48 459 0.56 725 Application Example 2 45 432 0.81 655 Application Example 3 44 414 0.80 603 Application Example 4 46 471 0.77 599 Application Example 5 42 389 0.82 555 Application Example 6 40 402 0.76 581 Application Example 7 45 398 0.73 577

[0101] The performance quality of the bio-based polyester composition obtained from the above comparative examples 1-6 was determined by using the same determination process, and the results are shown in Table 2.

[0102] Table 2

[0103] Comparative Example Breaking strength (MPa) Breaking elongation (%) PLLA phase size (pm) UPF Comparative Example 1 22 44 4.51 2 Comparative Example 2 29 102 4.35 21 Comparative Example 3 26 58 4.43 19 Comparative Example 4 27 98 4.31 17 Comparative Example 5 20 49 4.49 8 Comparative Example 6 29 76 4.26 22

[0104] As can be seen from Table 1 and Table 2, the breaking strength and breaking elongation of the polylactic acid and polypropylene carbonate blend (comparative example 1) are significantly improved after adding the Janus nanoparticles (application example 1), and the PLLA phase size is obviously reduced to below the micron level. It is indicated that the Janus nanoparticles are uniformly dispersed at the interface of the two phases at this time, and play a good compatibilization role, so that the mechanical properties of the bio-based polyester composition such as breaking strength and breaking elongation are improved. In comparative example 6, unmodified TiO2 hollow microspheres are added, and the breaking strength and breaking elongation are not obviously improved compared with the pure sample, and the PLLA phase size is not obviously reduced. It is indicated that the compatibility of the two polymers is not good, and the addition of TiO2 hollow microspheres does not play a good compatibilization role. As can be seen from the bio-based polyester composition with different Janus nanoparticle contents (application examples 1-3), with the addition of Janus nanoparticles, the compatibility is obviously improved, and the mechanical properties of the blend are also significantly improved. However, when the content of Janus nanoparticles is too high (comparative examples 2-4), the compatibility and mechanical properties of the bio-based polyester composition decrease to a certain extent, and the reason is that the nanoparticles are not uniformly distributed at this time, and too many nanoparticles are accumulated at the interface of the two phases and distributed in the two phases, which affects the mechanical properties of the blend. In addition, the temperature of melt blending also has a certain influence on the compatibility of the material (comparative example 5), when the temperature of melt blending is lower than 180℃, the PLLA does not melt sufficiently, so the tensile strength, breaking elongation and compatibility of the material are not obviously improved. On the other hand, the Janus nanoparticles selected in the application take TiO2 as the matrix, and further improve its functionality, so that the bio-based polyester composition has good ultraviolet resistance (application example 1) far higher than the excellent level (UPF50+). In summary, a strong and tough bio-based polyester composition film is prepared by the application, which is simple and practical, easy to industrialize, and is expected to be applied in the fields of film packaging materials, agricultural greenhouse film materials, etc.

[0105] The above examples are not intended to limit the scope of the present application, nor are the described steps intended to limit the order in which they are performed. Modifications apparent to one skilled in the art in light of the above teachings are intended to fall within the scope of the claims.

Claims

1. A Janus nanoparticle, characterized in that, The Janus nanoparticles are based on TiO2 hollow spheres as templates, with polypropylene carbonate diol and dextrorotatory polylactic acid modified on both sides of the template, respectively. The method for preparing the Janus nanoparticles includes the following steps: (1) PPCD reacts with lysine diisocyanate. After the reaction is complete, TiO2 hollow sphere dispersion is added to the system to obtain TiO2 hollow spheres with PPCD grafted on the outer surface. (2) TiO2 hollow spheres grafted with PPCD on the outer surface are ultrasonically crushed to obtain TiO2-PPCD nanoparticles, which are then reacted with silane coupling agent and dextrorotatory polylactic acid to obtain the Janus nanoparticles.

2. A method for preparing Janus nanoparticles as described in claim 1, characterized in that, The preparation method includes the following steps: (1) PPCD reacts with lysine diisocyanate. After the reaction is complete, TiO2 hollow sphere dispersion is added to the system to obtain TiO2 hollow spheres with PPCD grafted on the outer surface. (2) TiO2 hollow spheres grafted with PPCD on the outer surface are ultrasonically crushed to obtain TiO2-PPCD nanoparticles, which are then reacted with silane coupling agent and dextrorotatory polylactic acid to obtain the Janus nanoparticles.

3. The preparation method according to claim 2, characterized in that, In step (1), the molar ratio of polypropylene carbonate diol to lysine diisocyanate is 1:2-3.

5.

4. The preparation method according to claim 2, characterized in that, In step (1), the TiO2 hollow sphere dispersion is prepared by dispersing TiO2 hollow spheres in anhydrous ethanol; the concentration of the TiO2 hollow sphere dispersion is 1-1.5 g / 100 ml.

5. The preparation method according to claim 2, characterized in that, In step (1), the mass-to-volume ratio of PPCD to TiO2 hollow sphere dispersion is 0.3-0.5 / 100, g / ml.

6. The preparation method according to claim 2, characterized in that, In step (2), the silane coupling agent is KH560; the mass ratio of TiO2-PPCD nanoparticles, dextrorotatory polylactic acid and silane coupling agent is 1:2-5:5-10.

7. An application of the Janus nanoparticles according to claim 1, characterized in that, Used to prepare bio-based polyester compositions.

8. A bio-based polyester composition comprising the Janus nanoparticles of claim 1, characterized in that, The raw materials include the following parts by weight: 60-90 parts polypropylene carbonate, 10-40 parts polylactic acid (L-L), and 0.1-3 parts Janus nanoparticles.

9. A bio-based polyester material containing Janus nanoparticles as described in claim 1, characterized in that, The bio-based polyester material is obtained by melt blending 60-90 parts of polypropylene carbonate, 10-40 parts of polylactic acid (L-L), and 0.1-3 parts of Janus nanoparticles, followed by molding; the melt blending temperature is 180℃.

10. The application of the Janus nanoparticles of claim 1, the bio-based polyester composition of claim 8, or the bio-based polyester material of claim 9, characterized in that, Used in food packaging, agriculture, or aerospace.

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