1. A light-cured resin is characterized by comprising polypropylene fumarate and hyperbranched polyester acrylate.

2. The photocurable resin of claim 1, comprising 40-60 parts by weight of propylene fumarate and 40-60 parts by weight of hyperbranched polyester acrylate.

3. The photocurable resin of claim 1 or 2 further comprising a photoinitiator.

4. The photocurable resin of claim 3 wherein the photoinitiator is selected from the group consisting of phenyl bis (2,4, 6-trimethylbenzoyl) phosphine oxide, (2,4, 6-trimethylbenzoyl) diphenylphosphine oxide, photoinitiator 784 or photoinitiator 754; the photoinitiator is 0.5-3 parts by weight, preferably 1-2 parts by weight.

5. The method for producing a photocurable resin according to any one of claims 1 to 4, comprising the steps of: under the condition of keeping out of the sun, dissolving polypropylene fumarate, adding hyperbranched polyester acrylate, stirring, adding a photoinitiator, and mixing to obtain the photocuring resin.

6. The method according to claim 5, wherein the method comprises the steps of: mixing fumarate, 1, 2-propylene glycol, a catalyst and a polymerization inhibitor, carrying out a first-step reaction to obtain di (hydroxypropyl) fumarate, and then carrying out a second-step reaction to obtain the polypropylene glycol fumarate.

7. The method according to claim 6, wherein the weight ratio of the fumaric acid ester, the 1, 2-propanediol, the catalyst and the polymerization inhibitor is about 1: 3: 0.01: 0.002; the fumarate comprises diethyl fumarate; the catalyst comprises zinc chloride; the polymerization inhibitor is selected from one or two of hydroquinone and benzoquinone.

8. The preparation method according to claim 6, wherein the first step reaction is carried out by: adding fumarate and 1, 2-propylene glycol, stirring for 10-30 min, then adding a catalyst and a polymerization inhibitor, mixing, stirring and reacting at 90-110 ℃ for 20-40 min under the atmosphere of inert gas, then heating to 140-160 ℃, reacting for 6-8 h, and cooling to 90-110 ℃; the reaction process of the second step is as follows: reacting for 0.5-1 h at 90-110 ℃ under vacuum condition, and then heating to 140-160 ℃ for reacting for 3-5 h.

9. A scaffold for bone tissue engineering, which is produced by using the photocurable resin according to any one of claims 1 to 4.

10. Use of the photocurable resin according to any one of claims 1-4 in photocrosslinking 3D printing or bone tissue engineering.

Background

In orthopedics, bone defects and osteonecrosis are caused by primary and metastatic bone tumor resection, bone loss after skeletal trauma, and inflammation of bone tissue. The common bone defect repair uses autologous bone or allogeneic bone transplantation repair, but the autologous bone has limited source, and the allogeneic bone repair cannot reach the optimal repair level due to nondegradable property. At present, along with the development of tissue engineering technology, a biological porous scaffold with good biocompatibility, degradability and absorbability is constructed in vitro, and the scaffold is implanted into a defect part of an organism, so that the method is a tissue regeneration technical means with wide prospect and achieves the purposes of optimal wound repair and reconstruction functions.

Polypropylene Fumarate (PPF) meets design criteria for many orthopedic applications. PPF is an injectable and biodegradable polymer and has good application prospect. Due to its in situ cross-linking properties, it has been widely used in tissue engineering, especially as a bone regeneration material. PPF is an unsaturated linear polyester that can be crosslinked by carbon double bonds in the backbone and degraded to non-toxic products by simple hydrolysis of the ester bonds. The three-dimensional porous scaffold prepared from the PPF not only provides enough mechanical support, but also has the function of inducing the growth of bone tissues. ,

however, for different cases, the bone defect repair often needs to be customized by a personalized three-dimensional porous implant. The current popular high-precision 3D printing technology is the best scheme for precisely customizing the three-dimensional porous implant. The PPF material has a photo-crosslinking property, so that a high-precision three-dimensional porous implant is personalized and customized by using a stereolithography (Stereo Lithography) technology and a Digital Light Processing (Digital Light Processing) technology. In the prior art, a three-dimensional bone tissue engineering scaffold with a fine porous structure can be prepared by photo-crosslinking 3D printing, but pure PPF has high viscosity: at 40 ℃ the zero shear viscosity of a linear PPF with a weight average molecular weight of 1130g/mol is 24 pas and that of a PPF with a weight average molecular weight of 3340g/mol is as high as 11600 pas. Photo-crosslinked 3D printing, however, requires a polymer material with a relatively low viscosity (0.25-10Pa · s), and therefore pure PPF is not suitable for direct use in photo-crosslinked 3D printing, often requiring the addition of a reactive diluent, diethyl fumarate (DEF), to reduce the viscosity of the PPF. Thus, the 3D printing scheme of PPF is typically to dissolve it into reactive diluent DEF as solvent and cross-linker, thereby forming a printable PPF resin. Almost all current research on 3D printing of PPF uses DEF as a reactive diluent. However, as the DEF content increases, the mechanical properties of the prepared scaffold decrease dramatically and the curing speed is slow. This is mainly due to the fact that the composition of DEF changes the cross-linking network of the PPF, and that a small molecule of DEF contains only one double bond, which has a limited ability to provide cross-linking of the PPF and thus cannot meet the actual requirements.

Disclosure of Invention

The invention provides a light-cured resin, a preparation method and an application thereof, which aim to solve one or more technical problems in the prior art and at least provide a beneficial selection or creation condition.

In order to overcome the technical problems, the technical scheme adopted by the invention is as follows:

a light-cured resin comprises polypropylene fumarate and hyperbranched polyester acrylate.

It is worth mentioning that hyperbranched polymers are a class of polymers with a highly branched structure. Hyperbranched polyester acrylate (i.e., HPA) containing a large amount of C ═ C at the chain ends can be obtained by modifying hyperbranched polyester with methacrylic anhydride. The hyperbranched polyester acrylate has low viscosity, good fluidity and solubility and high chemical reaction activity. As a coating component for ultraviolet curing, the hyperbranched polyester acrylate contains a large number of external active end groups to provide crosslinking points, so that the hyperbranched polyester acrylate has the advantages of high curing speed, complete curing and good film coating performance. The hyperbranched polyester acrylate is used as a reactive diluent to dissolve the PPF, so that the viscosity of the PPF can be effectively reduced, and the hyperbranched polyester acrylate is suitable for photo-crosslinking 3D printing. Compared with diethyl fumarate, the hyperbranched polyester acrylate rich in carbon-carbon double bonds at the chain end can provide more crosslinking points and grab more PPF chain segments to form a more complete crosslinking network, so that the mechanical property of the stent is remarkably improved; the prepared light-cured resin can be quickly cured and molded under extremely low ultraviolet exposure energy, so that the 3D printing time is effectively saved, the printing efficiency is improved, and the prepared three-dimensional support is more in line with the design value of a model.

Further, the molecular weight of the polypropylene fumarate is about 2500 g/mol.

As a further improvement of the scheme, the light-cured resin comprises 40-60 parts by weight of propylene fumarate and 40-60 parts by weight of hyperbranched polyester acrylate.

As a further improvement of the above aspect, the photocurable resin further includes a photoinitiator.

As a further improvement of the above, the photoinitiator is selected from phenyl bis (2,4, 6-trimethylbenzoyl) phosphine oxide, (2,4, 6-trimethylbenzoyl) diphenylphosphine oxide, photoinitiator 784 or photoinitiator 754, preferably phenyl bis (2,4, 6-trimethylbenzoyl) phosphine oxide; the photoinitiator is 0.5-3 parts by weight, preferably 1-2 parts by weight.

The method for preparing the photocurable resin according to any one of the present invention comprises the steps of: under the condition of keeping out of the sun, dissolving polypropylene fumarate, adding hyperbranched polyester acrylate, stirring, adding a photoinitiator, and mixing to obtain the photocuring resin.

It is worth to be noted that the whole preparation process of the light-cured resin needs to be carried out under the condition of avoiding light, which is mainly because the raw materials of the light-cured resin already contain PPF, HPA and a photoinitiator, and the light-protected treatment is carried out before the light-crosslinked 3D printing, so that the components in the light-cured resin can be ensured not to have cross-linking reaction and curing, and the light-cured resin is in a stable mixed liquid state, and then when the light-crosslinked 3D printing is carried out, the light-cured resin can have cross-linking reaction and curing under the ultraviolet light exposure, and the light-cured resin is changed into a solid state from a liquid state, so that a printed finished product is obtained. The chemical reaction equation of HPA and PPF is as follows (wherein BAPO is photoinitiator, UV is ultraviolet ray, and PPF chain is PPF chain)

As a further improvement of the scheme, the preparation method of the poly propylene fumarate comprises the following steps: mixing fumarate, 1, 2-propylene glycol, a catalyst and a polymerization inhibitor, carrying out a first-step reaction to obtain di (hydroxypropyl) fumarate, and then carrying out a second-step reaction to obtain the polypropylene glycol fumarate.

As a further improvement of the above, the weight parts ratio of the fumarate, 1, 2-propanediol, catalyst and inhibitor is about 1: 3: 0.01: 0.002; the fumarate comprises diethyl fumarate; the catalyst comprises zinc chloride; the polymerization inhibitor is selected from one or two of hydroquinone and benzoquinone.

As a further improvement of the above scheme, the process of the first step reaction is as follows: adding fumarate and 1, 2-propylene glycol, stirring for 10-30 min, then adding a catalyst and a polymerization inhibitor, mixing, stirring and reacting at 90-110 ℃ for 20-40 min under the atmosphere of inert gas, then heating to 140-160 ℃, reacting for 6-8 h, and cooling to 90-110 ℃; the reaction process of the second step is as follows: reacting for 0.5-1 h at 90-110 ℃ under vacuum condition, and then heating to 140-160 ℃ for reacting for 3-5 h.

The bone tissue engineering scaffold is prepared by adopting the photocuring resin. The bone tissue engineering scaffold printed by using the light-cured resin as a raw material has excellent toughness, higher compression modulus, closer to the design value of a printing model and more excellent capability of recovering deformation after compression.

Use of a photocurable resin according to any one of the present invention in photocrosslinking 3D printing or bone tissue engineering. In the photo-crosslinking 3D printing according to the present invention, a dye is added, wherein the dye comprises orlistat yellow, and the dye is 0.03 to 0.3 parts by weight, preferably 0.1 to 0.15 parts by weight.

The invention has the beneficial effects that:

the invention provides a light-cured resin and a preparation method and application thereof, wherein polypropylene fumarate and hyperbranched polyester acrylate are compounded, wherein the hyperbranched polyester acrylate replaces diethyl fumarate to serve as a reactive diluent, so that not only is the viscosity of the polypropylene fumarate effectively reduced, but also the end group of the hyperbranched polyester acrylate has a plurality of double bonds and can provide more crosslinking points, and therefore, the PPF is effectively promoted to be rapidly cured within a very short ultraviolet exposure time and the light crosslinking reaction is complete, so that the light-cured resin prepared by the invention has a more perfect crosslinking network and more excellent mechanical properties, and is more suitable for photo-crosslinking 3D printing of three-dimensional bone tissue engineering scaffolds. The photocuring resin obtained by the invention can be applied to photocrosslinking 3D printing or bone tissue engineering, and has wide application prospect.

Drawings

FIG. 1 is a simplified schematic of a photocrosslinking 3D printing process in the present invention;

FIG. 2 is the results of the curing depth and penetration depth experiments of the stents obtained from the PPF/HPA photocurable resin of example 1 and the PPF/DEF photocurable resin of comparative example 1 in the present invention;

FIG. 3 is a viscosity curve of PPF/HPA photocurable resin of different component ratios in the present invention;

FIG. 4 is a schematic view showing the respective cross-linked networks of the PPF/HPA photocurable resin of example 1 and the PPF/DEF photocurable resin of comparative example 1 in the present invention;

FIG. 5 shows the results of the compressive modulus test of the hardly porous scaffolds and the solid scaffolds obtained in examples 4 to 5 and comparative examples 4 to 5, respectively, according to the present invention;

FIG. 6 is a result of a compression test of the three-dimensional porous scaffolds of example 4 and comparative example 4 in the present invention;

FIG. 7 is a simplified schematic of the photo-crosslinking 3D printing process of the minimal printed pattern in the present invention;

FIG. 8 is the results of mechanical tensile property tests of the PPF/HPA photocurable resin of example 1 and the PPF/DEF photocurable resin of comparative example 1 in the present invention.

For English in the figures, the corresponding translation is as follows:

model; sliring: slicing; UV curing: ultraviolet light curing; final Scaffold: a cured scaffold; post-curing: post-curing; scaffold: a support;

preset layer thickness: the thickness of a preset curing layer is thick; supports: supporting; cure Depth: curing depth; exposure: exposure energy;

PPF crossslinked network: a PPF cross-linked network; reactive component: a reactive diluent;

compressive module: a compressive modulus; and (4) ports: is porous; solid: solid;

minor axis: a minor axis; long axis: a long axis;

actual height/initial height: actual height/initial height;

tenfile module: a tensile modulus; breaking strand h: breaking strength; elongation at break: elongation at break; stress: stress; and (3) Strain: and (4) strain.

Detailed Description

The present invention is specifically described below with reference to examples in order to facilitate understanding of the present invention by those skilled in the art. It should be particularly noted that the examples are given solely for the purpose of illustration and are not to be construed as limitations on the scope of the invention, as non-essential improvements and modifications to the invention may occur to those skilled in the art, which fall within the scope of the invention as defined by the appended claims. Meanwhile, the raw materials mentioned below are not specified in detail and are all commercially available products; the process steps or extraction methods not mentioned in detail are all process steps or extraction methods known to the person skilled in the art.

Example 1

Synthesis of polypropylene fumarate (PPF):

50g of diethyl fumarate and 65.97g of 1, 2-propylene glycol were sequentially added to a three-necked flask, stirred at 150rpm under a nitrogen atmosphere (flow rate: 3 to 5 bubbles per second) for 20min, and then 0.39g of zinc chloride (ZnCl) was added₂) And 0.064g hydroquinone; stirring at 100 ℃ and 300rpm for reaction for 30min, heating to 150 ℃, reacting for 7h, and cooling to 100 ℃ to obtain the fumaric acid di (hydroxypropyl) ester; vacuum was applied, the reaction was carried out at 100 ℃ for 1 hour, and then the temperature was raised to 150 ℃ for 4 hours to obtain PPF having a molecular weight of about 2500 g/mol.

Preparation of PPF/HPA photocuring resin:

under the condition of keeping out of the sun, taking 15g of PPF to dissolve in 3ml of dichloromethane, using dichloromethane as a cosolvent, adding 15g of hyperbranched polyester acrylate after the PPF is fully dissolved, stirring resin liquid by using a stirrer to fully mix the resin liquid, adding 0.3g of photoinitiator phenyl bis (2,4, 6-trimethylbenzoyl) phosphine oxide, fully mixing for 12h, placing the mixture in a vacuum oven under the condition of room temperature after uniform mixing, vacuumizing for 12h to completely remove the cosolvent dichloromethane, and obtaining the PPF/HPA photocuring resin, which is recorded as PPF/HPA 50: 50.

example 2

Example 2 differs from example 1 in that the mass ratio of PPF to HPA in example 2 is 40: 60, the remaining components and the preparation were the same as in example 1. A PPF/HPA photocurable resin was obtained, noted PPF/HPA 40: 60.

example 3

Example 3 differs from example 1 in that the mass ratio of PPF to HPA in example 3 is 60: 40, the remaining components and the preparation were the same as in example 1. A PPF/HPA photocurable resin was obtained, noted PPF/HPA 60: 40.

comparative example 1

Comparative example 1 differs from example 1 in that in comparative example 1 DEF is used instead of the hyperbranched polyester acrylate of example 1, and the remaining components and preparation procedure are the same as in example 1. The resulting PPF/DEF photocurable resin was found to be noted PPF/DEF 50: 50.

comparative example 2

Comparative example 2 differs from example 1 in that the mass ratio of PPF to HPA in comparative example 1 is 20: 80, the remaining components and the preparation process were the same as in example 1. A PPF/HPA photocurable resin was obtained, noted PPF/HPA 20: 80.

comparative example 3

Comparative example 3 differs from example 1 in that the mass ratio of PPF to HPA in comparative example 1 is 80: 20, the remaining components and the preparation were the same as in example 1. The PPF/HPA photocurable resin was obtained and was noted as PPF/HPA 80: 20.

example 4 three-dimensional porous scaffold printing

The PPF/HPA light-cured resin of example 1 is taken, the dye basf orilix yellow is added, the weight portion is 0.15 portion, after the Z-axis direction precision is improved, the light-crosslinking 3D printing is carried out (the simple schematic diagram of the printing process is shown in figure 1), and the method comprises the following steps:

1) model design: inputting a mathematical function model cos (x) sin (y) + cos (y) sin (z) + cos (z) sin (x) -0.7 into K3DSurf software to obtain a porous and high-porosity three-dimensional stent model, wherein the overall shape of the stent is cylindrical, the diameter of the stent is 4.5mm, and the height of the stent is 6.5 mm;

2) and (3) model slicing treatment: exporting the three-dimensional support model into an STL format, and importing Creation works hop slicing software to cut into a two-dimensional projection graph;

3) inputting the picture information into a computer to perform layer-by-layer photocrosslinking 3D printing, wherein the printer is a nanoArch P140 printer of Mofang New materials science and technology Limited, the ultraviolet wavelength is 405nm, the printing layer thickness is 20 μm per layer, the ultraviolet exposure time of each layer is 2.8s, and the ultraviolet energy is 35mJ/cm²；

4) Carefully removing the bracket from the printing platform by using a blade, and removing redundant resin in the pores by a centrifugal method, wherein the centrifugal speed is 4500r/min, and the centrifugal time is 2 min;

5) and (3) putting the scaffold into a Form Cure curing box (Formlabs) for curing for 2h, wherein the wavelength of the curing box is 405nm, and obtaining the three-dimensional porous scaffold.

Comparative example 4

Comparative example 4 is different from example 4 in that the PPF/HPA photocurable resin in example 4 is replaced with PPF/DEF photocurable resin in comparative example 4, and the remaining components and preparation process are the same as in example 4.

Example 5 solid support printing

The PPF/HPA photocuring resin of example 1 is taken to carry out photocrosslinking 3D printing, 0.15 part by weight of dye bas-oljel yellow is added, and after the Z-axis direction precision is improved, the photocrosslinking 3D printing is carried out (the simple schematic diagram of the printing process is shown in figure 1), which comprises the following steps:

1) model design: inputting a mathematical function model cos (x) sin (y) + cos (y) sin (z) + cos (z) sin (x) -0.7 into K3DSurf software to obtain a porous and high-porosity three-dimensional stent model, wherein the overall shape of the stent is cylindrical, and the diameter of the stent is 3mm, and the height of the stent is 6 mm;

2) and (3) model slicing treatment: exporting the three-dimensional support model into an STL format, and importing Creation works hop slicing software to cut into a two-dimensional projection graph;

3) drawing(s)Inputting the information into a computer to perform layer-by-layer photocrosslinking 3D printing, wherein the printer is a nanoArch P140 printer of Mofang New materials science and technology Limited, the ultraviolet wavelength is 405nm, the printing layer thickness is 40 μm per layer, the ultraviolet exposure time per layer is 1.4s, and the ultraviolet energy is 20mJ/cm²；

4) Carefully removing the bracket from the printing platform by using a blade, and removing redundant resin in the pores by a centrifugal method, wherein the centrifugal speed is 4500r/min, and the centrifugal time is 2 min;

5) and (3) putting the support into a Form Cure curing box (Formlabs) for curing for 2h, wherein the wavelength of the curing box is 405nm, and obtaining the solid support.

Comparative example 5

Comparative example 5 is different from example 5 in that the PPF/HPA photocurable resin in example 5 was replaced with the PPF/DEF photocurable resin in comparative example 5, and the remaining components and preparation process were the same as in example 5.

Product performance test 1: depth of cure and penetration test

Carrying out photocrosslinking 3D printing on the PPF/HPA photocuring resin in example 1 and the PPF/DEF photocuring resin in comparative example 1 under different ultraviolet energy respectively to obtain different supports, measuring the actual curing layer thickness of the topmost layer of each support, and measuring different ultraviolet energy to obtain the curing depth, the penetration depth and the like of each support, wherein the adopted printing model and related test results are shown in figure 2, wherein (a) is the printing model (the thickness of the topmost layer is designed to be 40 μm); (b) the curing molding condition of PPF/HPA light-cured resin printed under different ultraviolet energy is adopted; (c) respectively representing exposure energy-curing depth curves of PPF/HPA light-cured resin and PPF/DEF light-cured resin; (d) the curing and molding conditions of the PPF/DEF photocuring resin printed under different ultraviolet energy are adopted.

As can be seen from (b) in FIG. 2, the PPF/HPA photocurable resin exhibited extremely low energy of ultraviolet light (4 mJ/cm)²) The material can be quickly cured and formed, and is stable in forming and free of obvious deformation; as the uv energy increases, the actual curing layer thickness of the topmost layer of the corresponding stent gradually decreases and the curing depth of the corresponding stent gradually increases, from which it can be seen that as the uv energy increasesAnd the actual curing layer thickness and curing depth of the topmost layer of the bracket printed by PPF/HPA photocuring resin are regularly changed, and the curing molding is rapid and stable without obvious deformation.

The inventor finds out through experiments that: the PPF/DEF light-cured resin is lower than 25mJ/cm²The exposure energy of (3) is not cured and molded, and the probability of printing failure is remarkably increased. Moreover, as can be seen from (d) in fig. 2, with the increase of the ultraviolet energy, the actual curing layer thickness and curing depth of the topmost layer of the corresponding bracket are irregularly changed, and the fluctuation is large and is obviously unstable. Therefore, with the increase of ultraviolet energy, the actual curing layer thickness and the curing depth of the topmost layer of the bracket printed by PPF/DEF photocuring resin are irregularly changed, the curing molding is unstable, and the deformation is obvious after the curing.

The actual top-most thickness of the printed object is then measured.

Meanwhile, the inventor also carries out penetration depth experiments on the PPF/HPA light-cured resin and the PPF/DEF light-cured resin respectively under different exposure energies, and the calculation formula is as follows: c_d＝D_p(lnE_max-lnE_c) (equation 1).

Wherein, C_dRefers to the depth of cure, D, of the photocurable resin_PDepth of penetration of the photocurable resin, E_cMeans critical curing energy of the photocurable resin, E_maxRefers to the output energy of the ultraviolet lamp. According to the formula 1, C_dAnd E_maxIs a known value, and the exposure energy-curing depth curves of the respective PPF/HPA photocurable resin and PPF/DEF photocurable resin obtained by the functional relationship are shown in (c) of FIG. 2, in which the intersection point of the ordinate of the curing depth curve is the critical curing energy (E) of the photocurable resin_c) Slope D_PIs the penetration depth of the light-curable resin. The parameters of the photocurable resin obtained from the curing depth curve are shown in table 1 below.

TABLE 1 Critical curing energy and penetration depth of PPF/HPA photocurable resin and PPF/DEF photocurable resin

From this, it can be seen that the critical curing energy E of the PPF/HPA photocurable resin_cThe curing agent is obviously lower than PPF/DEF photocureable resin, so that the PPF/HPA photocureable resin obtained by the invention can quickly react, quickly cure and completely crosslink under extremely low exposure energy.

Product performance test 2: rheology test

The photo-curable resins obtained in examples 1 to 3 and comparative examples 2 to 3 were subjected to rheological tests (frequency sweep of 0.5 to 100rad/s at 25 ℃) to measure zero shear viscosity and glass transition temperature data of the photo-curable resins of different compositions, which were respectively PPF/HPA 20: 80. 40: 60. 50: 50. 60: 40 and 80: 20. the viscosity curves of the PPF/HPA photocurable resins resulting in different component ratios are shown in FIG. 3, in which φ on the abscissa of the viscosity curves_PFFWhich means the ratio of PPF to (PPF + HPA), as is apparent from fig. 3, as the ratio of PPF increases, the zero shear viscosity of the resulting photocurable resin increases, which means that as the ratio of the reactive diluent component (HPA) increases, the zero shear viscosity of the resulting photocurable resin is significantly reduced, thereby indicating that the HPA component is effective in reducing the viscosity of pure PPF, making the resulting photocurable resin of the present invention suitable for photocrosslinking 3D printing.

Furthermore, it was confirmed from experimental studies that comparative examples 2(PPF/HPA 20: 80) having a zero shear viscosity of less than 0.25 pas and comparative example 3(PPF/HPA 80: 20) having a zero shear viscosity of more than 10 pas are not suitable for photocrosslinking 3D printing because the zero shear viscosity is in the range of 0.25 to 10 pas, and thus comparative examples 2 and 3 are not suitable for photocrosslinking 3D printing. This is mainly because, in comparative examples 2 and 3, the ratio of PPF to HPA is out of the range of the present invention, and therefore the zero shear viscosity of the obtained photocurable resin is also out of the range of 0.25-10 pas, while the shear viscosity of the photocurable resin obtained by the present invention is in the range of 0.25-10 pas after reasonable proportioning, and thus it is suitable for photocrosslinking reaction 3D printing.

Product performance test 3: gel content test

The PPF/HPA photocurable resin of example 1 and the PPF/DEF photocurable resin of comparative example 1 were each transferred to a silicone mold having a thickness of about 0.5mm, clamped by two glass plates (2.1mm thick) one above the other, and then left to stand under ultraviolet light (365nm) for 30 minutes (about 7cm from the base), and the crosslinked sheet was taken out after cooling to room temperature.

Weighing the slices (W)_o) Soaking in 20mL of dichloromethane, two days later vacuum-drying and weighing (W)_d) Therefore, the gel fraction (namely the gel content) of the block copolymer synthesized under different processes is calculated, and the formula is as follows:

gel fraction ═ W_o-W_d)/W_o*100％

The schematic diagrams of the respective crosslinked networks of the resulting PPF/HPA photocurable resin of example 1 and the PPF/DEF photocurable resin of comparative example 1 are shown in FIG. 4. The gel content of the PPF/HPA photocurable resin of example 1 after crosslinking was 92.0% + -2.8%, and the gel content of the PPF/DEF photocurable resin of comparative example 1 after crosslinking was 83.1% + -1.0%. The gel content shows that under the irradiation of ultraviolet rays, the cross-linked network formed in the PPF/HPA light-cured resin of the example 1 is more perfect, and the cross-linking reaction is more completely carried out; and further explains that under the condition of the same reactive diluent content, as the terminal group of the HPA has more double bonds, the HPA micromolecule can grab more chain segments to form a tighter and more perfect crosslinking network.

Product performance test 4: compression testing

A. The results of the compressive modulus test (compression rate of 0.5mm/min) of each of the hardly porous scaffolds and the solid scaffolds obtained in examples 4 to 5 and comparative examples 4 to 5, respectively, are shown in FIG. 5. As is apparent from fig. 5, the compressive modulus of the stent printed using the PPF/HPA photocurable resin of example 1 was higher than that using the PPF/DEF photocurable resin of comparative example 1, thereby demonstrating that the PPF/HPA photocurable resin has more excellent compressive mechanical properties.

B. The three-dimensional porous scaffolds of example 4 and comparative example 4 were respectively taken, the scaffold diameter, height, and actual dimensions of the major axis and the minor axis of the minimum printed pattern (fig. 6 is a simple schematic diagram of the photo-crosslinking 3D printing process of the minimum printed pattern) were respectively measured and compared with the printing model design values, thereby evaluating the stability of the scaffolds obtained by photo-crosslinking 3D printing of the photo-curable resins of different compositions. The actual measurement values and the model design values of the diameter, height, major axis, and minor axis of the three-dimensional porous scaffolds of example 4 and comparative example 4 are shown in table 2 below.

Table 2 actual measurement values and model design values of diameter, height, major axis, and minor axis of the three-dimensional porous scaffolds of example 4 and comparative example 4

As shown in table 2, from the four data of diameter, height, major axis and minor axis, it is obvious that the actual size of the stent printed by the PPF/DEF photocurable resin is different from the design value of the printing model, while the actual size of the stent printed by the PPF/HPA photocurable resin is closer to the design value of the printing model, mainly because the stability of the stent during the 3D photo-crosslinking printing is effectively improved by the faster and more complete photo-crosslinking of the PPF/HPA photocurable resin.

C. The three-dimensional porous scaffolds of example 4 and comparative example 4 were respectively subjected to a compression test, and the recovery deformation capacities of both porous scaffolds were measured after applying 50% compression deformation, with the results shown in fig. 7.

As can be seen from fig. 7, the porous scaffold recovers its shape at room temperature after the stress is removed after applying 50% of the compression set. The main reason is that the stent prepared by the PPF/HPA light-cured resin has better toughness and a more perfect crosslinking system, has stronger capability of recovering deformation after compression, and is obviously superior to the stent prepared by the PPF/DEF light-cured resin of the comparative example 4.

Product performance test 5: tensile test

The PPF/HPA photocurable resin of example 1 and the PPF/DEF photocurable resin of comparative example 1 were each transferred to a silicone mold having a thickness of about 0.5mm, the mold was dumbbell-shaped, and the upper and lower sides were clamped by two glass plates (2.1mm thick), and then they were left to stand under irradiation with ultraviolet light (365nm) for 1 hour (about 7cm from the base), and the crosslinked sheet was taken out after cooling to room temperature and used for a tensile test.

The mechanical tensile properties including tensile modulus, breaking strength and breaking elongation, etc. were characterized by testing at a tensile rate of 1mm/min, and the results are shown in fig. 8, in which (a) are the tensile modulus test results of the PPF/HPA photocurable resin of example 1 and the PPF/DEF photocurable resin of comparative example 1; (b) the results of the fracture strength test of the PPF/HPA photocurable resin of example 1 and the PPF/DEF photocurable resin of comparative example 1; (c) the results of elongation at break tests for the PPF/HPA photocurable resin of example 1 and the PPF/DEF photocurable resin of comparative example 1; (d) the stress-strain curves for the PPF/HPA photocurable resin of example 1 and the PPF/DEF photocurable resin of comparative example 1 were obtained. It is apparent from fig. 8 that the PPF/HPA photocurable resin of example 1 has higher tensile modulus and tensile strength, thus illustrating that the PPF/HPA photocurable resin of example 1 exhibits more excellent tensile mechanical properties.

It will be obvious to those skilled in the art that many simple derivations or substitutions can be made without inventive effort without departing from the inventive concept. Therefore, simple modifications to the present invention by those skilled in the art according to the present disclosure should be within the scope of the present invention. The above embodiments are preferred embodiments of the present invention, and all similar processes and equivalent variations to those of the present invention should fall within the scope of the present invention.