Method for programming a shape memory polymer while defining the switch temperature by selection of the programming temperature
The invention relates to a method for programming a shape memory polymer, which comprises at least one switching segment having at least one thermal phase transition and covalent and/or non-covalent cross-linking points such that the shape memory polymer after the programming thereof is in a position to transition from a programmed temporary shape into the permanent shape thereof, following a temperature increase to a temperature that at least corresponds to a switching temperature (T switch , T σmax ). According to the invention, the method comprises (a) predetermining a programming temperature (t prog ) as a function of a desired switching temperature (T switch , T σmax ), (b) heating the shape memory polymer to the predetermined programming temperature (t prog ), and transferring the polymer into a shape that corresponds to the temporary shape by applying a forced molding state, and (c) cooling the polymer to a temperature below the desired switching temperature (T switch , T σmax ) while maintaining the forced molding state.
1. A method for programming a shape memory polymer or a composite material of such a polymer and magnetic particles dispersed therein, which has at least one switching segment with at least one thermal phase transition and covalent and/or non-covalent crosslinking points, so that, after its programming, the shape memory polymer is capable of undergoing a transition from a programmed temporary shape (A) to its permanent shape (B) after a temperature increase to a temperature (T high ) which corresponds at least to a switching temperature (T switch , T σmax ) of the polymer, the programming having the following steps:
(a) predetermination of a programming temperature (T prog ) as a function of a desired switching temperature (T switch , T σmax ), wherein the predetermination is effected computationally
with the use of an empirically determined mathematical relationship between the programming temperature (T prog ) and the switching temperature (T switch , T σmax )
or
with the use of an empirically determined characteristic diagram containing parameter pairs comprising programming temperature (T prog ) and switching temperature (T switch , T σmax ),
(b) heating of the shape memory polymer to the predetermined programming temperature (T prog ) being higher than the switching temperature (T switch , T σmax ), and transformation of the polymer into a shape corresponding to the temporary shape by use of forced shaping and
(c) cooling the polymer to a temperature below the desired switching temperature (T switch , T σmax ) while maintaining the forced shaping.
2. The method as claimed in claim 1 , wherein the method for programming is carried out several times in succession for a given shape memory polymer, different programming temperatures (T prog ) being used for the respective programming cycles and hence different switching temperatures (T switch , T σmax ) being programmed.
3. The method as claimed in claim 1 , wherein in that the method for programming is carried out for a plurality of shape memory polymers of identical composition, in each case different programming temperatures (T prog ) being used for the individual shape memory polymers and hence different switching temperatures (T switch , T σmax ) being programmed.
4. The method as claimed claim 1 , wherein the switching segment of the shape memory polymer is a semicrystalline segment having a melt transition (T m ) or an amorphous segment with a glass transition (T g ).
5. The method as claimed in claim 1 , wherein the programming temperature T prog is selected from a range of at least ±20 K around the thermodynamic phase transition temperature T trans of the at least one switching segment.
6. The method as claimed in claim 1 , wherein, in the case of a shape memory polymer which has two switching segments and two thermodynamic phase transition temperatures T trans,A and T trans,B , the programming temperature T prog is selected from a range from at least T trans,A ±20 K to T trans,B ±20 K.
7. The method as claimed in claim 1 , wherein a non-porous material or a porous, open-pore or closed-pore material is used as a shape memory polymer.
8. The method as claimed in claim 1 , wherein the method for programming is carried out several times in succession for a given shape memory polymer, different programming temperatures (T prog ) being used for the respective programming cycles and hence different switching temperatures (T switch , T δ.max ) being programmed; and
the predetermination is effected computationally with the use of an empirically determined mathematical relationship between the programming temperature (T prog ) and the switching temperature (T switch , T σmax ).
9. The method as claimed in claim 1 , wherein the method for programming is carried out several times in succession for a given shape memory polymer, different programming temperatures (T prog ) being used for the respective programming cycles and hence different switching temperatures (T switch , T δ.max ) being programmed; and
the predetermination of the programming temperature (T prog ) is effected with the use of an empirically determined characteristic diagram containing parameter pairs comprising programming temperature (T prog ) and switching temperature T switch , T σmax ).
10. The method as claimed in claim 1 , wherein the method for programming is carried out for a plurality of shape memory polymers of identical composition, in each case different programming temperatures (T prog ) being used for the individual shape memory polymers and hence different switching temperatures (T switch , T δ.max ) being programmed; and
the predetermination is effected computationally with the use of an empirically determined mathematical relationship between the programming temperature (T prog ) and the switching temperature (T switch , T σmax ).
11. The method as claimed in claim 1 , wherein the method for programming is carried out for a plurality of shape memory polymers of identical composition, in each case different programming temperatures (T prog ) being used for the individual shape memory polymers and hence different switching temperatures (T switch , T δ.max ) being programmed; and
the predetermination of the programming temperature (T prog ) is effected with the use of an empirically determined characteristic diagram containing parameter pairs comprising programming temperature (T prog ) and switching temperature (T switch , T σmax ).
12. The method as claimed in claim 2 , wherein the method for programming is carried out for a plurality of shape memory polymers of identical composition, in each case different programming temperatures (T prog ) being used for the individual shape memory polymers and hence different switching temperatures (T switch , T δ.max ) being programmed.
13. The method as claimed in claim 1 , wherein the switching segment of the shape memory polymer is a semicrystalline segment having a melt transition (T m ) or an amorphous segment with a glass transition (T g ); and
the predetermination is effected computationally with the use of an empirically determined mathematical relationship between the programming temperature (T prog ) and the switching temperature (T switch , T σmax ).
14. The method as claimed in claim 1 , wherein the switching segment of the shape memory polymer is a semicrystalline segment having a melt transition (T m ) or an amorphous segment with a glass transition (T g ); and
the predetermination of the programming temperature (T prog ) is effected with the use of an empirically determined characteristic diagram containing parameter pairs comprising programming temperature (T prog ) and switching temperature (T switch , T σmax ).
15. The method as claimed in claim 2 , wherein the switching segment of the shape memory polymer is a semicrystalline segment having a melt transition (T m ) or an amorphous segment with a glass transition (T g ).
16. The method as claimed in claim 3 , wherein the switching segment of the shape memory polymer is a semicrystalline segment having a melt transition (T m ) or an amorphous segment with a glass transition (T g ).
17. The method as claimed in claim 1 , wherein the programming temperature T prog is selected from a range of at least .+−0.20 K around the thermodynamic phase transition temperature T trans of the at least one switching segment; and
the predetermination is effected computationally with the use of an empirically determined mathematical relationship between the programming temperature (T prog ) and the switching temperature (T switch , T σmax ).
18. The method as claimed in claim 1 , wherein the programming temperature T prog is selected from a range of at least .+−0.20 K around the thermodynamic phase transition temperature T trans of the at least one switching segment; and
the predetermination of the programming temperature (T prog ) is effected with the use of an empirically determined characteristic diagram containing parameter pairs comprising programming temperature (T prog ) and switching temperature (T switch , T σmax ).