# US 12,005,633 B2 · Method for photo-curing four-dimensional (4D) printing of multi-layer structure with adjustable shape recovery speed, and multi-layer structure prepared by photo-curing 4D printing

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- Number: US 12,005,633 B2
- Document ID: US12005633B2
- Status: Granted
- Kind: B2
- Application number: 18/273,034
- Filed: 2022-12-16
- Published: 2024-05-02
- Granted: 2024-06-11
- Earliest claimed: 2022-06-06
- Assignees: Jiangsu University
- Applicants: Jiangsu University
- Inventors: Shu Huang; Hang Zhang; Jianzhong Zhou; Jie Sheng; Jiean Wei; Hongwei Yang; Cheng Wang; Mingyuan Shan
- Web page: https://patentgrep.com/patent/US12005633B2

## CPC

- B29C 64/129: characterised by the energy source therefor, e.g. by global irradiation combined with a mask
- B29C 64/124: using layers of liquid which are selectively solidified
- B29C 64/393: for controlling or regulating additive manufacturing processes
- B32B 7/027: Thermal properties
- B32B 27/08: of synthetic resin
- B32B 27/20: using fillers, pigments, thixotroping agents
- B32B 27/40: comprising polyurethanes
- B33Y 10/00: Processes of additive manufacturing
- B33Y 50/02: for controlling or regulating additive manufacturing processes
- B33Y 80/00: Products made by additive manufacturing
- B29K 2075/00: Use of {PU, i.e.} polyureas or polyurethanes {or derivatives thereof}, as moulding material
- B29K 2507/04: Carbon
- B32B 2264/10: Inorganic particles
- Y02P 10/25: Process efficiency
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B33Y: ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

The present disclosure provides a method for photo-curing 4D printing of a multi-layer structure with an adjustable shape recovery speed, and a multi-layer structure printed thereby. The multi-layer structure printed by the method for photo-curing 4D printing of the multi-layer structure with the adjustable shape recovery speed includes a plurality of deformation units sequentially connected in series, and each of the plurality of the deformation units includes two slow layers, a fast layer, and a transition layer; and the fast layer is arranged between the two slow layers, and the transition layer is arranged between at least one of the two slow layers and the fast layer. In the present disclosure, a low cross-linking layer is doped with a nanocarbon light-absorbing material to solve the problem that the low cross-linking layer is prone to over-curing when a high cross-linking layer is printed on the low cross-linking layer.

## Claims

### Claim 1

A method for photo-curing four-dimensional (4D) printing of a multi-layer structure with an adjustable shape recovery speed, comprising the following steps:
printing a slow layer, wherein an ultraviolet irradiation energy used during the printing of the slow layer is Islow, and a molecular chain cross-linking degree during the printing of the slow layer is Dslow;
printing a transition layer on the slow layer, wherein an ultraviolet irradiation energy used during the printing of the transition layer gradiently decreases in a thickness direction of the printing;
printing a fast layer on the transition layer, wherein an ultraviolet irradiation energy used during the printing of the fast layer is Ifast; a molecular chain cross-linking degree during the printing of the fast layer is Dfast; Islow>Ifast, and Dslow>Dfast; and the fast layer comprises a nanocarbon light-absorbing material to absorb ultraviolet light to reduce an exposure energy of incident light; and
printing the slow layer on the fast layer.

### Claim 2 (depends on 1)

The method for photo-curing 4D printing of the multi-layer structure with the adjustable shape recovery speed according to claim 1, wherein the ultraviolet irradiation energy Islow used during the printing of the slow layer is 4 times the ultraviolet irradiation energy Ifast used during the printing of the fast layer.

### Claim 3 (depends on 1)

The method for photo-curing 4D printing of the multi-layer structure with the adjustable shape recovery speed according to claim 1, wherein the molecular chain cross-linking degree Dslow during the printing of the slow layer is 1.8 times the molecular chain cross-linking degree Dfast during the printing of the fast layer.

### Claim 4 (depends on 1)

The method for photo-curing 4D printing of the multi-layer structure with the adjustable shape recovery speed according to claim 1, wherein a gradient change range of the ultraviolet irradiation energy Itransition used during the printing of the transition layer in the thickness direction of the printing is as follows: Ifast≤Itransition≤3 Ifast.

### Claim 5 (depends on 1)

The method for photo-curing 4D printing of the multi-layer structure with the adjustable shape recovery speed according to claim 1, wherein a nanocarbon material in the fast layer is one of or a mixture of a carbon nanotube and graphene, and a weight fraction content of the nanocarbon material in the fast layer is 0.6%.

### Claim 6 (depends on 1)

A multi-layer structure prepared by photo-curing 4D printing, wherein the multi-layer structure is printed by the method for photo-curing 4D printing of the multi-layer structure with the adjustable shape recovery speed according to claim 1; the multi-layer structure comprises a plurality of deformation units sequentially connected in series, and each of the plurality of the deformation units comprises two slow layers, a fast layer, and a transition layer; and the fast layer is arranged between the two slow layers, and the transition layer is arranged between at least one of the two slow layers and the fast layer.

### Claim 7 (depends on 6)

The multi-layer structure prepared by photo-curing 4D printing according to claim 6, wherein the plurality of the deformation units each have a same thickness, and the slow layers, the fast layer, and the transition layer respectively maintain a same thickness across the plurality of the deformation units; and a shape recovery speed is accelerated by synchronously increasing a layer thickness proportion of the fast layer of each of the plurality of the deformation units and/or decreasing a layer thickness proportion of the slow layers of each of the plurality of the deformation units.

### Claim 8 (depends on 6)

The multi-layer structure prepared by photo-curing 4D printing according to claim 6, wherein the plurality of the deformation units each have a same thickness, and sequential shape memory recoveries are achieved by increasing a layer thickness proportion of the fast layer of each of the plurality of the deformation units sequentially or decreasing a layer thickness proportion of the slow layers of each of the plurality of the deformation units sequentially, according to a series-connection sequence of the plurality of the deformation units.

### Claim 9 (depends on 2)

A multi-layer structure prepared by photo-curing 4D printing, wherein the multi-layer structure is printed by the method for photo-curing 4D printing of the multi-layer structure with the adjustable shape recovery speed according to claim 2; the multi-layer structure comprises a plurality of deformation units sequentially connected in series, and each of the plurality of the deformation units comprises two slow layers, a and the fast layer.

### Claim 10 (depends on 9)

The multi-layer structure prepared by photo-curing 4D printing according to claim 9, wherein the plurality of the deformation units each have a same thickness, and the slow layers, the fast layer, and the transition layer respectively maintain a same thickness across the plurality of the deformation units; and a shape recovery speed is accelerated by synchronously increasing a layer thickness proportion of the fast layer of each of the plurality of the deformation units and/or decreasing a layer thickness proportion of the slow layers of each of the plurality of the deformation units.

### Claim 11 (depends on 9)

The multi-layer structure prepared by photo-curing 4D printing according to claim 9, wherein the plurality of the deformation units each have a same thickness, and sequential shape memory recoveries are achieved by increasing a layer thickness proportion of the fast layer of each of the plurality of the deformation units sequentially or decreasing a layer thickness proportion of the slow layers of each of the plurality of the deformation units sequentially, according to a series-connection sequence of the plurality of the deformation units.

### Claim 12 (depends on 3)

A multi-layer structure prepared by photo-curing 4D printing, wherein the multi-layer structure is printed by the method for photo-curing 4D printing of the multi-layer structure with the adjustable shape recovery speed according to claim 3; the multi-layer structure comprises a plurality of deformation units sequentially connected in series, and each of the plurality of the deformation units comprises two slow layers, a and the fast layer.

### Claim 13 (depends on 12)

The multi-layer structure prepared by photo-curing 4D printing according to claim 12, wherein the plurality of the deformation units each have a same thickness, and the slow layers, the fast layer, and the transition layer respectively maintain a same thickness across the plurality of the deformation units; and a shape recovery speed is accelerated by synchronously increasing a layer thickness proportion of the fast layer of each of the plurality of the deformation units and/or decreasing a layer thickness proportion of the slow layers of each of the plurality of the deformation units.

### Claim 14 (depends on 12)

The multi-layer structure prepared by photo-curing 4D printing according to claim 12, wherein the plurality of the deformation units each have a same thickness, and sequential shape memory recoveries are achieved by increasing a layer thickness proportion of the fast layer of each of the plurality of the deformation units sequentially or decreasing a layer thickness proportion of the slow layers of each of the plurality of the deformation units sequentially, according to a series-connection sequence of the plurality of the deformation units.

### Claim 15 (depends on 4)

A multi-layer structure prepared by photo-curing 4D printing, wherein the multi-layer structure is printed by the method for photo-curing 4D printing of the multi-layer structure with the adjustable shape recovery speed according to claim 4; the multi-layer structure comprises a plurality of deformation units sequentially connected in series, and each of the plurality of the deformation units comprises two slow layers, a and the fast layer.

### Claim 16 (depends on 15)

The multi-layer structure prepared by photo-curing 4D printing according to claim 15, wherein the plurality of the deformation units each have a same thickness, and the slow layers, the fast layer, and the transition layer respectively maintain a same thickness across the plurality of the deformation units; and a shape recovery speed is accelerated by synchronously increasing a layer thickness proportion of the fast layer of each of the plurality of the deformation units and/or decreasing a layer thickness proportion of the slow layers of each of the plurality of the deformation units.

### Claim 17 (depends on 15)

The multi-layer structure prepared by photo-curing 4D printing according to claim 15, wherein the plurality of the deformation units each have a same thickness, and sequential shape memory recoveries are achieved by increasing a layer thickness proportion of the fast layer of each of the plurality of the deformation units sequentially or decreasing a layer thickness proportion of the slow layers of each of the plurality of the deformation units sequentially, according to a series-connection sequence of the plurality of the deformation units.

### Claim 18 (depends on 5)

A multi-layer structure prepared by photo-curing 4D printing, wherein the multi-layer structure is printed by the method for photo-curing 4D printing of the multi-layer structure with the adjustable shape recovery speed according to claim 5; the multi-layer structure comprises a plurality of deformation units sequentially connected in series, and each of the plurality of the deformation units comprises two slow layers, a and the fast layer.

### Claim 19 (depends on 18)

The multi-layer structure prepared by photo-curing 4D printing according to claim 18, wherein the plurality of the deformation units each have a same thickness, and the slow layers, the fast layer, and the transition layer respectively maintain a same thickness across the plurality of the deformation units; and a shape recovery speed is accelerated by synchronously increasing a layer thickness proportion of the fast layer of each of the plurality of the deformation units and/or decreasing a layer thickness proportion of the slow layers of each of the plurality of the deformation units.

### Claim 20 (depends on 18)

The multi-layer structure prepared by photo-curing 4D printing according to claim 18, wherein the plurality of the deformation units each have a same thickness, and sequential shape memory recoveries are achieved by increasing a layer thickness proportion of the fast layer of each of the plurality of the deformation units sequentially or decreasing a layer thickness proportion of the slow layers of each of the plurality of the deformation units sequentially, according to a series-connection sequence of the plurality of the deformation units.