
==== Front
Sci Rep
Sci Rep
Scientific Reports
2045-2322
Nature Publishing Group UK London

39251784
72053
10.1038/s41598-024-72053-3
Article
A facile strategy for synthesizing isosorbide-based polyurethane structural adhesives and core–shell rubber
Min Jin-Gyu
Lim Won-Bin
Lee Ju-Hong
Lee Jae-Ryong
Bae Ji-Hong jhbae@pusan.ac.kr

Huh PilHo pilho.huh@pusan.ac.kr

https://ror.org/01an57a31 grid.262229.f 0000 0001 0719 8572 Department of Polymer Science and Engineering, Pusan National University, Busan, 46241 South Korea
9 9 2024
9 9 2024
2024
14 2101822 11 2023
3 9 2024
© The Author(s) 2024
2024
https://creativecommons.org/licenses/by-nc-nd/4.0/ Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.
A structural adhesive series of biomass-based polyurethane (Biomass-PU) is synthesized using polypropylene glycol (PPG2000), isosorbide-based polyol (RPO300) as polyols, isophorone diisocyanate (IPDI) as an isocyanate and 4-tert-butylphenol (BP) as a capping agent. Three different equivalent ratios of PPG2000/RPO300, 9/1 (Biomass-PU1), 7/3 (Biomass-PU2), and 1/1 (Biomass-PU3), are evaluated to determine the effect of isosorbide-based polyol content on the properties and the optimizing formulation of biomass-PU structure adhesive. The 9/1 ratio of PPG2000/RPO300 substantially leads to the improvement of impact strength by up to 35 MPa, and the PPG2000/RPO300 = 9/1 ratio exhibits better thermal properties and impact strength than those of other ratios. To achieve more compatibility between biomass-PU structure adhesive and core–shell rubber (CSR) toughener, novel CSRs are successfully synthesized using acryl-PU as a shell and biomass-based PU as a core. The chemical structure of biomass-PU structure adhesives is analyzed through FT-IR Spectroscopy and NCO% titration. Thermal properties are evaluated using TGA and DSC analysis. Their molecular weights are measured by GPC. Also, the core–shell rubber (CSR) with a polyurethane shell is prepared to reinforce the impact strength of Biomass-PU structure adhesive.

Subject terms

Chemistry
Engineering
Materials science
issue-copyright-statement© Springer Nature Limited 2024
==== Body
pmcIntroduction

A polyurethane structural adhesive (PSA) has been increasingly on the rise in the industrial world and speedy development due to excellent application properties, such as high toughness and much lower viscosity compared to epoxy or acrylic adhesives1–3. PSAs are specific adhesive that play an important role in modern materials including plastics, metals, ceramic, and composite materials4–6. PSA can be available in the area of rigid structure such as construction, automobile, and aerospace applications7–9. Specifically, PSA can be an excellent candidate for bonding to a multitude of high strength applications where flexibility is required and have the combination of high toughness, good impact and vibration resistance that makes these adhesives an ideal choice for joining both lightweight and difficult-to-bond substrates10–12. PSA resins are usually synthesized by the reaction of polyols and diisocyanates, with polyols being the soft segments and diisocyanates being the hard segments13–15. Synthetic polyurethane (PU) resins are generally petroleum-based materials, non-biodegradable, a serious threat of human health and environmental hazards16–18. To achieve these carbon-free society, eco-sustainability and non-toxicity, biomass-based polyurethanes has been one of today’s most popular materials, which can play a key role in fostering environmental goals of promoting CO2 reduction and sustainability19–21. Biomass is renewable organic material that comes from plants and animals, such as wood, forestry by-products, agricultural crops, biogenic materials, animal manure, and human sewage, which can be burned directly for heat or converted to liquid and gaseous fuels through various processes. Biomass-based PU can be synthesized using polyols extracted from nature-derived resources and be also an environmental-friendly material that can replace petroleum-based polyurethane22–24. The resistance properties against impact in high-performance materials can be a key performance of structural adhesives25–27. Furthermore, the improvement in quality and performance of structural adhesives has been continuously demanded due to the direct relation to safety, strength, durability, and environmental issues28–30. A continuous increase in fracture toughness and impact strength was reported by the addition of core–shell rubber (CSR) in the epoxy polymers17,18,31. Usually, the shell of CSR is a glassy polymer, such as PMMA and polystyrene, and the core should be considered as elastic phase, such as rubber and polyurethane9–11. Various types of CSR can be utilized to improve the impact strength of these structural adhesive materials11–13.

The aims of this study are to synthesize a biomass-PU structure adhesive and novel CSRs based on acryl-PU shell and biomass-based PU core1. Reducing the neat petroleum content in the CSR system can be an effective way to achieve good CO2-free and high eco-sustainability with little toughness loss15–17. The synthetic method of a novel CSR series containing petroleum PU shell and biomass-based PU core, instead of flexible rubber and rigid PMMA, to balance the good properties of toughness and CO2-free benefit is mainly tried in this study and discussed as well11–13,19. Compared to the typical CSR structures prepared in previous studies, the novel CSR designs with petroleum PU shell or biomass-based PU core can be more environmental benefits and have much higher processing efficiency20,24. This approach may provide a new strategy that can contribute to the development of industrially and eco-friendly required high-performance PSA29.

Results

A biomass-based polyurethane (biomass-based PU) series is synthesized to use the main resin of a structural adhesive, through a prepolymer method of two-step. FT-IR is analyzed to identify the occurrence of urethane linkage in the molecular backbone. Figure 1 shows the step-wise FT-IR spectra to synthesize a biomass-based PU before and after the end-capping. With going the reaction process, the –NCO peak of 2250 cm−1 disappears due to the complete reaction between the hydroxyl groups (-OH) and the isocyanates (-NCO) as shown in Fig. 1. A strong absorption band at 3383 and 3378 cm−1 also can be assigned to the hydrogen bonding between N–H and carbonyl groups (C = O)32–34. The successful reaction of isosorbide-polyols with isocyanates is confirmed by the appearance of the expected characteristic peaks in their FT-IR spectra, indicating the successful synthesis of biomass-based PU. And molecular weight and NCO% of the synthesized a biomass-based polyurethane structural adhesive series are summarized in Table 1.Fig. 1 FT-IR result of synthesized biomass-based polyurethane.

Table 1 Biomass-based polyurethane synthesis molecular weight and NCO%.

Sample name	GPC	NCO%	
Mn (g/mol)	Mw (g/mol)	PDI (Mw/Mn)	Theoretical value	Measured value	
Ref	7716	9706	1.26	3.44	3.68	
Biomass-PU1	7934	9985	1.26	3.77	3.77	
Biomass-PU2	7396	8984	1.21	4.26	4.31	
Biomass-PU3	8049	10090	1.25	5.06	5.19	

The thermal behavior of a biomass-based PU series is studied using thermogravimetric (TGA) and differential scanning calorimetry (DSC). Figure 2 shows TGA and DSC curves of a biomass-based PU series synthesized with different equivalent ratios of PPG2000/RPO300. The three weight loss stages of biomass-based PUs are observed in the range from the degradation starting at 140 ℃ to the ending at 400 ℃, as shown in Fig. 2(A). The first degradation of a biomass-based PU series occurs at temperatures of 153.9 ℃, 143.4 ℃, and 144.1 ℃, which may result from the evaporation of low molecular weight compounds and the dissociation of weak intermolecular linkages to isocyanates and residual isosorbide-based polyol. In comparison with petroleum PU, the Td value of a biomass-based PU series is increased from 3.5% to 11.1%. The second degradation occurs over the temperature range of 200 to 300 ℃, which may arise from the dissociation of urethane linkages11. The third degradation of 300 to 400 ℃ may be occurred due to the intensified decomposition of urethane bonds and the scission of methyl chains in the polyol blocks20,21,34,35. As shown in Fig. 2(B), the DSC curves of a petroleum PU and a biomass-based PU series shows the glass transition temperatures (Tg) due to flexibility of the soft segments at about −56.3 ℃, and −54.4 ℃, −52.9 ℃, and −35.2 ℃, respectively. A biomass-based PU series made in the ranging from 3.7 to 4.4 NCO% can be characterized as a PU structure adhesive exhibiting similar thermal properties when compared to a petroleum PU. The shifts of Tg from −35.2 ℃ to −54.4 ℃ and −52.9 ℃ at the lower temperature may be attributed to the presence of excess –NCO in the PU moieties. It can be explained that excess –NCO in biomass-based PU may lead to a somewhat lesser reaction to form three-dimensional allophanate or biuret crosslinking, which results in an increase of Tg36,37.Fig. 2 Thermal properties of biomass-based polyurethane. (A) TGA curves / (B) DSC curves.

The shear and impact strength of a biomass-based PU series are shown in Fig. 3 and compared to those of a petroleum PU. Biomass-based PUs have relatively higher shear strength than that of a petroleum PU. Impact strength changes more dramatically than shear strength due to the effectiveness or reactivity of isosorbide-based polyol used in biomass-PU structural adhesives, as shown in Fig. 3. Interestingly, when the NCO% is less than 3.8, the biomass-based PU demonstrates an unexpectedly high impact strength.Fig. 3 Shear strength and impact strength of biomass-based polyurethane.

A schematic procedure for preparing the typical petroleum core–shell rubber (CSR) is presented, along with the preparation strategies for novel CSRs using a petroleum acryl-PU shell or a biomass-based PU core. The morphology and size of the typical petroleum CSR is evaluated using different three drying types. Figure 4 shows the FE-SEM images of typical petroleum CSRs prepared by spray-drying, oven-drying, and freeze-drying. The spherical CSR particles can be seen clearly in all drying types. From Fig. 4, it can be seen CSR particles by both oven-drying and freeze-drying process forms the damaged spherical-shapes while the perfectly spherical CSR shapes are successfully formed through spray-drying process. The average diameter of CSR by spray-drying is measured to be 5 μm ± 1 μm, as shown in Fig. 4(A) Ref38.Fig. 4 FE-SEM measurement results by drying method in CSR Fig. 7. (A) spray-drying (50 μm), (B) oven-drying (1 μm), (C) freeze-drying (1 μm).

The surface morphology of novel CSRs with petroleum acryl-PU shell or biomass-based PU core is measured to verify the formation of spherical particles and presented in Fig. 5. The perfectly-spherical CSR structures based on the petroleum acryl-PU shell or biomass-based PU core are observed by using a spray-drying method. As shown in Fig. 5, the particle size distribution of both CSRs is somewhat broad and the individual average particle diameter is 1 and 3 μm. Although some voids are formed into particles, the surface of both novel CSRs is smooth without any defect in spherical shape and external structures are almost compact39,40.Fig. 5 FE-SEM image after spray drying of CSR polymerization series. (A) petroleum PUA as a shell type / (B) isosorbide-based PU as a core type.

Thermal properties of novel CSRs with petroleum acryl-PU shell or biomass-based PU core are investigated by TGA and DSC. The TGA and DSC curves are shown in Fig. 6. Both CSRs exhibit two thermal-degradation and glass-transition temperatures, respectively. Decomposition temperatures (Td) for CSR Fig. 8(A) and Fig. 8(B) are observed at approximately 320–420 ℃ and 250–450 ℃, respectively, as shown in Fig. 6(A). The thermal decomposition profiles indicate different stability characteristics, with CSR Fig. 8(A) exhibiting a higher onset decomposition temperature compared to CSR Fig. 8(B). Glass-transition temperatures (Tg) are observed for both CSRs, attributed to their core–shell structures, as shown in Fig. 6(B). CSR Fig. 8(A) shows a Tg at approximately −39.62 ℃, associated with the HTPB core and petroleum acryl-PU shell. CSR Fig. 8(B), on the other hand, exhibits a Tg around −1.41 ℃, corresponding to the biomass-based PU core and MMA shell. The substantial difference in Tg values between the two schemes reflects the influence of the feedstock materials and their respective reactivities on the thermal properties of the CSRs41,42.Fig. 6 Thermal properties of CSR polymerization series. (A) petroleum PUA as a shell type / (B) isosorbide-based PU as a core type.

Discussion

A structural adhesive series based on the biomass-based polyol is successfully prepared using polypropylene glycol as a co-polyol, isophorone diisocyanate as an isocyanate and 4-tert-butylphenol (BP) as a capping agent, and the effect of isosorbide-based polyol (RPO300) content is evaluated to determine the properties and the optimizing formulation of a biomass-PU structure adhesive. An increase in RPO300 content leads to improved shear strength, while the reduction of RPO300 content provides a marked increase in thermal properties and impact strength43,44.

The interesting strategies to prepare the novel CSRs are suggested in this study. For the synthetic method of CSR structures, acryl-PU is used as a shell and biomass-based PU is used as a core. Morphology of the synthesized CSRs indicates that the perfectly spherical particles are successfully formed by using a spray-drying process and their distribution is somewhat uniform45,46. This study can allow a facile and efficient strategy to create a biomass-based structural adhesive and a novel CSR, and also provides an important contribution to versatile modern-industries due to the increasing attentions of environment-friendly protocol and the using need of biomass-based materials in high-performance structural adhesives46.

Methods

Figure 7 illustrates the process of forming core–shell rubber (CSR) similarly to previous studies, using hydroxyl terminated polybutadiene (HTPB) as the core material35. Divinylbenzene (DVB) was utilized as the crosslinker, Potassium persulfate (KPS) as the initiator, Sodium dodecyl sulfate (SDS) as the surfactant, and 1-dodecanethiol as the chain transfer agent.Fig. 7 A synthetic procedure for Ref. CSR.

As shown in Fig. 8(A), The shell was composed of polyurethane-acrylate (PUA), synthesized by polymerizing PPG1000, IPDI, and 2-HEMA at a molar ratio of 1:2:1.2. To reduce the viscosity of the PUA shell, 30 wt% of methyl methacrylate (MMA) was added36–38. Among the various acrylates tested, the results showed that the use of 2-HEMA resulted in the lowest viscosity. Figure 8(B) outlines the synthesis of CSR with a water-dispersed polyurethane (WPU) core and a methyl methacrylate (MMA) shell. A polyol blend of EI5 (Mn = 365 g/mol) was reacted with H12MDI and DMBA in a nitrogen-purged 250 mL reactor at 80 ℃ and 150 RPM. After monitoring the FT-IR and ensuring the disappearance of the NCO peak, HTPB was introduced to react with residual -NCO groups. Triethanolamine (TEA) was then added to impart ionic properties. The resulting mixture was dispersed in distilled water at 600 RPM, followed by acetone removal at 60 ℃. Finally, KPS, 1-dodecanethiol, and DVB were introduced, and MMA was added dropwise at controlled intervals to complete the shell formation.Fig. 8 A synthetic procedure for novel CSRs (A) involves using petroleum PUA as a shell and (B) isosorbide-based PU as a core.

Figure 9 presents a schematic diagram of the polymerization procedure for synthesizing biomass-based polyurethane. Polypropylene glycol (PPG2000, Mn = 2,000 g/mol), isosorbide-based polyol (RPO300, Mn = 1,252 g/mol), and isophorone diisocyanate (IPDI, Mn = 222.3 g/mol) were mixed at 70 ℃ and stirred at 150 RPM. 4-tert-butylphenol (BP, Mn = 150.22 g/mol) was added as a capping agent. Dibutyltin dilaurate (DBTDL, Mn = 631.56 g/mol) was used as a catalyst. The reaction continued until the disappearance of the -NCO peak, indicating complete capping. Polymerization was carried out with varying RPO300 ratios, resulting in three formulations: Biomass-PU1 (9/1), Biomass-PU2 (7/3), and Biomass-PU3 (1/1).Fig. 9 Biomass-based polyurethane synthesis.

Supplementary Information

Supplementary Information.

Supplementary Information

The online version contains supplementary material available at 10.1038/s41598-024-72053-3.

Acknowledgements

This work was supported by Industrial Strategic Technology Development Program (Bio tackifier adhesive material with a biomass content of 50% or more, 20010807). This work was supported by the Yang-Young Foundation, Samyang Corporation of Korea.

Author contributions

J.-G.Min conceived the experiment(s) and first author, J.-G.Min, J.-H.Bae and P.Huh conducted the experiment(s). W.-B.Lim, J.-H.Lee and J.-R.Lee analyzed the results. J.-G. Min discussed the experiment(s) with J.-H.Bae and P.Huh, J.-G.Min wrote the paper, all authors reviewed the manuscript.

Data availability

All data generated or analyzed during this study are included in this published article [and its supplementary information files].

Competing interests

The authors declare no competing interests.

Publisher's note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
==== Refs
References

1. Baek DY Sim KB Kim HJ Mechanical characterization of core-shell rubber/epoxy polymers for automotive structural adhesives as a function of operating temperature Polymers 2021 13 734 10.3390/polym13050734 33673513
Baek, D. Y., Sim, K. B. & Kim, H. J. Mechanical characterization of core-shell rubber/epoxy polymers for automotive structural adhesives as a function of operating temperature. Polymers 13, 734. 10.3390/polym13050734 (2021).33673513 10.3390/polym13050734
2. Lee HR Lee SJ Lim CY Seo JD Kim MS Kim JK The effect of nano functionalized block copolymer addition on the joint strength of structural epoxy adhesive for car body assembly J. Weld. Join. 2015 33 44 49 10.5781/JWJ.2015.33.4.44
Lee, H. R. et al. The effect of nano functionalized block copolymer addition on the joint strength of structural epoxy adhesive for car body assembly. J. Weld. Join. 33, 44–49. 10.5781/JWJ.2015.33.4.44 (2015).10.5781/JWJ.2015.33.4.44
3. Kim DY Lee DG Kim JC Lim CS Kong NS Kim JH Jung HW Noha SM Park YI Effect of molecular weight of polyurethane toughening agent on adhesive strength and rheological characteristics of automotive structural adhesives Int. J. Adhes. Adhes. 2017 74 21 27 10.1016/j.ijadhadh.2016.12.006
Kim, D. Y. et al. Effect of molecular weight of polyurethane toughening agent on adhesive strength and rheological characteristics of automotive structural adhesives. Int. J. Adhes. Adhes. 74, 21–27. 10.1016/j.ijadhadh.2016.12.006 (2017).10.1016/j.ijadhadh.2016.12.006
4. Ruan M Luan H Wang G Shen M Bio-polyols synthesized from bio-based 1,3-propanediol and applications on polyurethane reactive hot melt adhesives Ind. Crops Prod. 2019 128 436 444 10.1016/j.indcrop.2018.11.045
Ruan, M., Luan, H., Wang, G. & Shen, M. Bio-polyols synthesized from bio-based 1,3-propanediol and applications on polyurethane reactive hot melt adhesives. Ind. Crops Prod. 128, 436–444. 10.1016/j.indcrop.2018.11.045 (2019).10.1016/j.indcrop.2018.11.045
5. Borrero-López AM Guzmán DB González-Delgado JA Arteaga JF Valencia C Pischel U Franco JM Toward UV-triggered curing of solvent-free polyurethane adhesives based on castor oil ACS Sustain. Chem. Eng. 2021 9 11032 11040 10.1021/acssuschemeng.1c02461
Borrero-López, A. M. et al. Toward UV-triggered curing of solvent-free polyurethane adhesives based on castor oil. ACS Sustain. Chem. Eng. 9, 11032–11040. 10.1021/acssuschemeng.1c02461 (2021).10.1021/acssuschemeng.1c02461
6. Alfonso AT Sánchez MC Franco JM Preparation, characterization and mechanical properties of bio-based polyurethane adhesives from isocyanate-functionalized cellulose acetate and castor oil for bonding wood Polymers 2017 9 132 10.3390/polym9040132 30970811
Alfonso, A. T., Sánchez, M. C. & Franco, J. M. Preparation, characterization and mechanical properties of bio-based polyurethane adhesives from isocyanate-functionalized cellulose acetate and castor oil for bonding wood. Polymers 9, 132. 10.3390/polym9040132 (2017).30970811 10.3390/polym9040132
7. Tavares LB Boas CV Schleder GR Nacas AM Rosa DS Santos DJ Bio-based polyurethane prepared from Kraft lignin and modified castor oil Express Polym. Lett. 2016 10 927 940 10.3144/expresspolymlett.2016.86
Tavares, L. B. et al. Bio-based polyurethane prepared from Kraft lignin and modified castor oil. Express Polym. Lett. 10, 927–940. 10.3144/expresspolymlett.2016.86 (2016).10.3144/expresspolymlett.2016.86
8. Zain NM Roslin EN Ahmad S Preliminary study on bio-based polyurethane adhesive/aluminum laminated composites for automotive applications Int. J. Adhes. Adhes. 2016 71 1 9 10.1016/j.ijadhadh.2016.08.001
Zain, N. M., Roslin, E. N. & Ahmad, S. Preliminary study on bio-based polyurethane adhesive/aluminum laminated composites for automotive applications. Int. J. Adhes. Adhes. 71, 1–9. 10.1016/j.ijadhadh.2016.08.001 (2016).10.1016/j.ijadhadh.2016.08.001
9. Haschick R Mueller K Klapper M Muellen K Nonaqueous emulsions as a tool for particles with unique core-shell topologies Macromolecules 2008 10.1021/ma800550z
Haschick, R., Mueller, K., Klapper, M. & Muellen, K. Nonaqueous emulsions as a tool for particles with unique core-shell topologies. Macromolecules10.1021/ma800550z (2008).10.1021/ma800550z
10. Li S Wu Q Zhu H Lin Q Wang C Impact resistance enhancement by adding core-shell particle to epoxy resin modified with hyperbranched polymer Polymers 2017 9 684 10.3390/polym9120684 30965986
Li, S., Wu, Q., Zhu, H., Lin, Q. & Wang, C. Impact resistance enhancement by adding core-shell particle to epoxy resin modified with hyperbranched polymer. Polymers 9, 684. 10.3390/polym9120684 (2017).30965986 10.3390/polym9120684
11. Javni I Petrovic ZD Guo A Rachel F Thermal stability of polyurethane based vegetables oils J. Appl. Polym. Sci. 2000 77 1723 1734 10.1002/1097-4628(20000822)77:8<1723::AID-APP9>3.0.CO;2-K
Javni, I., Petrovic, Z. D., Guo, A. & Rachel, F. Thermal stability of polyurethane based vegetables oils. J. Appl. Polym. Sci. 77, 1723–1734 (2000).10.1002/1097-4628(20000822)77:8<1723::AID-APP9>3.0.CO;2-K
12. Park JH Baek DY Shin JH Jang SW Kim HJ Kim JH Song HK Hwang JW Yoo MJ Resistance to cleavage of core-shell rubber/epoxy composite foam adhesive under impact wedge-peel condition for automobile structural adhesive Polymer 2019 11 152 10.3390/polym11010152
Park, J. H. et al. Resistance to cleavage of core-shell rubber/epoxy composite foam adhesive under impact wedge-peel condition for automobile structural adhesive. Polymer 11, 152. 10.3390/polym11010152 (2019).10.3390/polym11010152
13. Antonino LD Garcia GES Viani CO Gouveia JR Vidotti SE Santos DJ Effects of core–shell and reactive liquid rubbers incorporation on practical adhesion and fracture energy of epoxy adhesives Iran. Polym. J. 2021 30 1329 1338 10.1007/s13726-021-00976-z
Antonino, L. D. et al. Effects of core–shell and reactive liquid rubbers incorporation on practical adhesion and fracture energy of epoxy adhesives. Iran. Polym. J. 30, 1329–1338. 10.1007/s13726-021-00976-z (2021).10.1007/s13726-021-00976-z
14. Qian JY Pearson RA Dimonie VL El-Aasser MS Synthesis and application of core–shell particles as toughening agents for epoxies J. Appl. Polym. Sci. 1995 58 439 448 10.1002/app.1995.070580222
Qian, J. Y., Pearson, R. A., Dimonie, V. L. & El-Aasser, M. S. Synthesis and application of core–shell particles as toughening agents for epoxies. J. Appl. Polym. Sci. 58, 439–448. 10.1002/app.1995.070580222 (1995).10.1002/app.1995.070580222
15. Petrović ZS Ferguson J Polyurethane elastomers Prog. Polym. Sci. 1991 16 5 695 836 10.1016/0079-6700(91)90011-9
Petrović, Z. S. & Ferguson, J. Polyurethane elastomers. Prog. Polym. Sci. 16(5), 695–836. 10.1016/0079-6700(91)90011-9 (1991).10.1016/0079-6700(91)90011-9
16. Giannakopoulos G Masania K Taylor A Toughening of epoxy using core-shell particles J. Mater. Sci. 2010 46 327 338 10.1007/s10853-010-4816-6
Giannakopoulos, G., Masania, K. & Taylor, A. Toughening of epoxy using core-shell particles. J. Mater. Sci. 46, 327–338. 10.1007/s10853-010-4816-6 (2010).10.1007/s10853-010-4816-6
17. Lin SP Han JL Yeh JT Chang FC Hsieh KH Composites of UHMWPE fiber reinforced PU/epoxy grafted interpenetrating polymer networks Eur. Polym. J. 2007 43 996 1008 10.1016/j.eurpolymj.2006.12.001
Lin, S. P., Han, J. L., Yeh, J. T., Chang, F. C. & Hsieh, K. H. Composites of UHMWPE fiber reinforced PU/epoxy grafted interpenetrating polymer networks. Eur. Polym. J. 43, 996–1008. 10.1016/j.eurpolymj.2006.12.001 (2007).10.1016/j.eurpolymj.2006.12.001
18. Mousavi SR Estaji S Javidi MR Paydayesh A Khonakdar HA Arjmand M Rostami E Jafari SH Toughenig of epoxy resin systems using core-shell rubber particles: A literature review J. Mater. Sci. 2021 56 18345 18367 10.1007/s10853-021-06329-8
Mousavi, S. R. et al. Toughenig of epoxy resin systems using core-shell rubber particles: A literature review. J. Mater. Sci. 56, 18345–18367. 10.1007/s10853-021-06329-8 (2021).10.1007/s10853-021-06329-8
19. Park CY Effect of PPG, MDI, 2-HEMA and butyl acrylate content on the properties of polyurethane adhesive Elastomers Compos. 2014 49 245 252 10.7473/EC.2014.49.3.245
Park, C. Y. Effect of PPG, MDI, 2-HEMA and butyl acrylate content on the properties of polyurethane adhesive. Elastomers Compos. 49, 245–252. 10.7473/EC.2014.49.3.245 (2014).10.7473/EC.2014.49.3.245
20. Kong XH Liu GG Curtis JM Characterization of canola oil based polyurethane wood adhesives Int. J. Adhes. Adhes. 2011 31 6 559 564 10.1016/j.ijadhadh.2011.05.004
Kong, X. H., Liu, G. G. & Curtis, J. M. Characterization of canola oil based polyurethane wood adhesives. Int. J. Adhes. Adhes. 31(6), 559–564. 10.1016/j.ijadhadh.2011.05.004 (2011).10.1016/j.ijadhadh.2011.05.004
21. Lee CS Ooi TL Chuan CH Synthesis of palm oil-based diethanolamides J. Am. Oil Chem. Soc. 2007 84 945 952 10.1007/s11746-007-1123-8
Lee, C. S., Ooi, T. L. & Chuan, C. H. Synthesis of palm oil-based diethanolamides. J. Am. Oil Chem. Soc. 84, 945–952. 10.1007/s11746-007-1123-8 (2007).10.1007/s11746-007-1123-8
22. Calpena EO Aís FA Torró-Palau AM Parreño EM Barceló CO Synthesis of polyurethanes from CO2-based polyols: A challenge for sustainable adhesives Int. J. Adhes. Adhes. 2016 67 63 68 10.1016/j.ijadhadh.2015.12.027
Calpena, E. O., Aís, F. A., Torró-Palau, A. M., Parreño, E. M. & Barceló, C. O. Synthesis of polyurethanes from CO2-based polyols: A challenge for sustainable adhesives. Int. J. Adhes. Adhes. 67, 63–68. 10.1016/j.ijadhadh.2015.12.027 (2016).10.1016/j.ijadhadh.2015.12.027
23. Kim IT Joo SH Oh JS Trends of Eco-friendly Polyurethane and Fillers J. Adhes. Interface. 2019 20 116 126 10.17702/jai.2019.20.3.116
Kim, I. T., Joo, S. H. & Oh, J. S. Trends of Eco-friendly Polyurethane and Fillers. J. Adhes. Interface. 20, 116–126. 10.17702/jai.2019.20.3.116 (2019).10.17702/jai.2019.20.3.116
24. Velde NV Javornik S Sever T Štular D Šobak M Štirn Ž Likozar B Jerman I Bio-based epoxy adhesives with lignin-based aromatic monophenols replacing bisphenol A Polymers 2021 13 3879 10.3390/polym13223879 34833178
Velde, N. V. et al. Bio-based epoxy adhesives with lignin-based aromatic monophenols replacing bisphenol A. Polymers 13, 3879. 10.3390/polym13223879 (2021).34833178 10.3390/polym13223879
25. Deka H Karak N Bio-based hyperbranched polyurethane/clay nanocomposites: Adhesive, mechanical, and thermal properties Polym. Adv. Technol. 2011 22 973 980 10.1002/pat.1603
Deka, H. & Karak, N. Bio-based hyperbranched polyurethane/clay nanocomposites: Adhesive, mechanical, and thermal properties. Polym. Adv. Technol. 22, 973–980. 10.1002/pat.1603 (2011).10.1002/pat.1603
26. Tavares LB Boas CV Schleder GR Nacas AM Rosa DS Santos DJ Bio-based polyurethane prepared from Kraft lignin and modified castor oil Express Polym. Lett. 2017 10 927 940 10.3144/expresspolymlett.2016.86
Tavares, L. B. et al. Bio-based polyurethane prepared from Kraft lignin and modified castor oil. Express Polym. Lett. 10, 927–940. 10.3144/expresspolymlett.2016.86 (2017).10.3144/expresspolymlett.2016.86
27. Jo YJ Choi SH Lee EY Production of biopolyols, bioisocyanates and biopolyurethanes from renewable biomass Appl. Chem. Eng. 2013 24 579 586 10.14478/ace.2013.1081
Jo, Y. J., Choi, S. H. & Lee, E. Y. Production of biopolyols, bioisocyanates and biopolyurethanes from renewable biomass. Appl. Chem. Eng. 24, 579–586. 10.14478/ace.2013.1081 (2013).10.14478/ace.2013.1081
28. Cywar RM Rorrer NA Hoyt CB Beckham GT Echen EYX Bio-based polymers with performance-advantaged properties Nat. Rev. Mater. 2022 7 83 103 10.1038/s41578-021-00363-3
Cywar, R. M., Rorrer, N. A., Hoyt, C. B., Beckham, G. T. & Echen, E. Y. X. Bio-based polymers with performance-advantaged properties. Nat. Rev. Mater. 7, 83–103. 10.1038/s41578-021-00363-3 (2022).10.1038/s41578-021-00363-3
29. Pan X Tian Y Li J Tan Q J, Ren. Bio-based polyurethane reactive hot-melt adhesives derived from isosorbide-based polyester polyols with different carbon chain lengths Chem. Eng. Sci. 2022 264 118152 10.1016/j.ces.2022.118152
Pan, X., Tian, Y., Li, J., Tan, Q. & J, Ren.,. Bio-based polyurethane reactive hot-melt adhesives derived from isosorbide-based polyester polyols with different carbon chain lengths. Chem. Eng. Sci. 264, 118152. 10.1016/j.ces.2022.118152 (2022).10.1016/j.ces.2022.118152
30. Li L Wang M Wu X Yi W Xiao Q Bio-based polyurethane nanocomposite thin coatings from two comparable POSS with eight same vertex groups for controlled release urea Sci. Rep. 2021 11 9917 10.1038/s41598-021-89254-9 33972621
Li, L., Wang, M., Wu, X., Yi, W. & Xiao, Q. Bio-based polyurethane nanocomposite thin coatings from two comparable POSS with eight same vertex groups for controlled release urea. Sci. Rep. 11, 9917. 10.1038/s41598-021-89254-9 (2021).33972621 10.1038/s41598-021-89254-9
31. Kim DY Kim SC Park YI Kim YC Lim CS The physical properties analysis of epoxy resins incorporated with toughening agents J. Adhes. Interface. 2015 16 101 106 10.17702/jai.2015.16.3.101
Kim, D. Y., Kim, S. C., Park, Y. I., Kim, Y. C. & Lim, C. S. The physical properties analysis of epoxy resins incorporated with toughening agents. J. Adhes. Interface. 16, 101–106. 10.17702/jai.2015.16.3.101 (2015).10.17702/jai.2015.16.3.101
32. Liu Y Liang HQ Li S Liu D Long YJ Liang GD Zhu FM Preparation of waterborne polyurethane with high solid content and elasticity J. Polym. Res. 2019 26 146 10.1007/s10965-019-1795-4
Liu, Y. et al. Preparation of waterborne polyurethane with high solid content and elasticity. J. Polym. Res. 26, 146. 10.1007/s10965-019-1795-4 (2019).10.1007/s10965-019-1795-4
33. Zia KM Barikani M Zuber M Bhatti IA Sheikh MA Molecular engineering of chitin based polyurethane elastomers Carbohydr. Polym. 2008 74 149 158 10.1016/j.carbpol.2008.03.013
Zia, K. M., Barikani, M., Zuber, M., Bhatti, I. A. & Sheikh, M. A. Molecular engineering of chitin based polyurethane elastomers. Carbohydr. Polym. 74, 149–158. 10.1016/j.carbpol.2008.03.013 (2008).10.1016/j.carbpol.2008.03.013
34. Sadeghi M Semsarzadeh MA Barikani M Ghalei B The effect of urethane and urea content on the gas permeation properties of poly(urethane-urea) membranes J. Membr. Sci. 2010 354 40 47 10.1016/j.memsci.2010.02.070
Sadeghi, M., Semsarzadeh, M. A., Barikani, M. & Ghalei, B. The effect of urethane and urea content on the gas permeation properties of poly(urethane-urea) membranes. J. Membr. Sci. 354, 40–47. 10.1016/j.memsci.2010.02.070 (2010).10.1016/j.memsci.2010.02.070
35. Kang SH Kim DY Kim TH Lee WJ Kim HG Chung JS Lim CS Chang SM Seo BK Toughening epoxy resins with core-shell (HTPB-PMMA/PMA) rubber particles J. Nanosci. Nanotechnol. 2017 17 7429 7435 10.1166/jnn.2017.14781
Kang, S. H. et al. Toughening epoxy resins with core-shell (HTPB-PMMA/PMA) rubber particles. J. Nanosci. Nanotechnol. 17, 7429–7435. 10.1166/jnn.2017.14781 (2017).10.1166/jnn.2017.14781
36. Zhu Z Li R Zhang C Gong S Preparation and properties of high solid content and low viscosity waterborne polyurethane—acrylate emulsion with a reactive emulsifier Polymers 2018 10 154 10.3390/polym10020154 30966190
Zhu, Z., Li, R., Zhang, C. & Gong, S. Preparation and properties of high solid content and low viscosity waterborne polyurethane—acrylate emulsion with a reactive emulsifier. Polymers 10, 154. 10.3390/polym10020154 (2018).30966190 10.3390/polym10020154
37. Zhang SF Wang RM He YF Song PF Wu ZM Waterborne polyurethane-acrylic copolymers crosslinked core–shell nanoparticles for humidity-sensitive coatings Prog. Org. Coat. 2013 76 729 735 10.1016/j.porgcoat.2013.01.003
Zhang, S. F., Wang, R. M., He, Y. F., Song, P. F. & Wu, Z. M. Waterborne polyurethane-acrylic copolymers crosslinked core–shell nanoparticles for humidity-sensitive coatings. Prog. Org. Coat. 76, 729–735. 10.1016/j.porgcoat.2013.01.003 (2013).10.1016/j.porgcoat.2013.01.003
38. Choi WC Lee WK Ha CS Low-viscosity UV-curable polyurethane acrylates containing dendritic acrylates for coating metal sheets J. Coat. Technol. Res. 2018 16 377 385 10.1007/s11998-018-0117-9
Choi, W. C., Lee, W. K. & Ha, C. S. Low-viscosity UV-curable polyurethane acrylates containing dendritic acrylates for coating metal sheets. J. Coat. Technol. Res. 16, 377–385. 10.1007/s11998-018-0117-9 (2018).10.1007/s11998-018-0117-9
39. Saxon DJ Luke AM Sajjad H Tolman WB Reineke TM Next-generation polymers: Isosorbide as a renewable alternative Prog. Polym. Sci. 2020 101 101196 10.1016/j.progpolymsci.2019.101196
Saxon, D. J., Luke, A. M., Sajjad, H., Tolman, W. B. & Reineke, T. M. Next-generation polymers: Isosorbide as a renewable alternative. Prog. Polym. Sci. 101, 101196. 10.1016/j.progpolymsci.2019.101196 (2020).10.1016/j.progpolymsci.2019.101196
40. Besse V Auvergne R Carlotti S Boutevin G Otazaghine B Caillol S Pascault JP Boutevin B Synthesis of isosorbide based polyurethanes: An isocyanate free method React. Funct. Polym. 2013 73 588 594 10.1016/j.reactfunctpolym.2013.01.002
Besse, V. et al. Synthesis of isosorbide based polyurethanes: An isocyanate free method. React. Funct. Polym. 73, 588–594. 10.1016/j.reactfunctpolym.2013.01.002 (2013).10.1016/j.reactfunctpolym.2013.01.002
41. Chen M Ren Synthesis of renewable isosorbide-based polyurethane acrylate resins for UV-cured coating with adjustable properties Prog. Org. Coat. 2023 182 107695 10.1016/j.porgcoat.2023.107695
Chen, M. et al. Ren Synthesis of renewable isosorbide-based polyurethane acrylate resins for UV-cured coating with adjustable properties. Prog. Org. Coat. 182, 107695. 10.1016/j.porgcoat.2023.107695 (2023).10.1016/j.porgcoat.2023.107695
42. Kim HN Lee DW Ryu H Song GS Lee DS Preparation and characterization of isosorbide-based self-healable polyurethane elastomers with thermally reversible bonds Molecules 2019 24 1061 10.3390/molecules24061061 30889870
Kim, H. N., Lee, D. W., Ryu, H., Song, G. S. & Lee, D. S. Preparation and characterization of isosorbide-based self-healable polyurethane elastomers with thermally reversible bonds. Molecules 24, 1061. 10.3390/molecules24061061 (2019).30889870 10.3390/molecules24061061
43. Lee JY Chin IJ Choi HJ Effect of particle size and crosslinking on the toughening of core-shell-type rubber-modified poly(lactic acid) composites Polym. Test. 2018 65 440 449 10.1016/j.polymertesting.2017.12.028
Lee, J. Y., Chin, I. J. & Choi, H. J. Effect of particle size and crosslinking on the toughening of core-shell-type rubber-modified poly(lactic acid) composites. Polym. Test. 65, 440–449. 10.1016/j.polymertesting.2017.12.028 (2018).10.1016/j.polymertesting.2017.12.028
44. Haehnle B Schuster PA Chen L Kuehne AJC All-conjugated polymer core-shell and core–shell–shell particles with tunable emission profiles and white light emission Small. 2021 17 2101411 10.1002/smll.202101411
Haehnle, B., Schuster, P. A., Chen, L. & Kuehne, A. J. C. All-conjugated polymer core-shell and core–shell–shell particles with tunable emission profiles and white light emission. Small. 17, 2101411. 10.1002/smll.202101411 (2021).10.1002/smll.202101411
45. Ramli RA Laftah WA Hashim S Core–shell polymers: A review RSC Adv. 2013 3 15543 15565 10.1039/C3RA41296B
Ramli, R. A., Laftah, W. A. & Hashim, S. Core–shell polymers: A review. RSC Adv. 3, 15543–15565. 10.1039/C3RA41296B (2013).10.1039/C3RA41296B
46. Mousavi SR Estaji S Javidi MR Paydayesh A Khonakdar HA Arjmand M Rostami E Jafari SH Toughening of epoxy resin systems using core–shell rubber particles: A literature review J. Mater. Sci. 2021 56 18345 18367 10.1007/s10853-021-06329-8
Mousavi, S. R. et al. Toughening of epoxy resin systems using core–shell rubber particles: A literature review. J. Mater. Sci. 56, 18345–18367. 10.1007/s10853-021-06329-8 (2021).10.1007/s10853-021-06329-8
