how do I extract top half of the data into a separate matrix and the bottom half into its own matrix?

ThermodynamicProperties =

1.0e+03 *

0.2000 0.0002 2.6129 2.8161

0.2500 0.0002 2.7047 2.9356

0.3000 0.0002 2.7897 3.0463

0.3500 0.0002 2.8727 3.1542

0.4000 0.0003 2.9555 3.2613

0.5000 0.0003 3.1234 3.4770

NaN NaN NaN NaN

NaN NaN NaN NaN

0.2000 0.0001 2.6027 2.8030

0.2500 0.0002 2.6989 2.9279

0.3000 0.0002 2.7857 3.0409

0.3500 0.0002 2.8697 3.1501

0.4000 0.0002 2.9531 3.2581

0.5000 0.0003 3.1218 3.4748

Answer 1

[KSSV]

A = 1.0e+03 *[ 0.2000    0.0002    2.6129    2.8161
    0.2500    0.0002    2.7047    2.9356
    0.3000    0.0002    2.7897    3.0463
    0.3500    0.0002    2.8727    3.1542
    0.4000    0.0003    2.9555    3.2613
    0.5000    0.0003    3.1234    3.4770
       NaN       NaN       NaN       NaN
       NaN       NaN       NaN       NaN
    0.2000    0.0001    2.6027    2.8030
    0.2500    0.0002    2.6989    2.9279
    0.3000    0.0002    2.7857    3.0409
    0.3500    0.0002    2.8697    3.1501
    0.4000    0.0002    2.9531    3.2581
    0.5000    0.0003    3.1218    3.4748] ; 
    
idx = find(isnan(A(:,1))) ;

B = A(1:idx(1)-1,:) ; 
A(1:idx(1)+length(idx),:) = [] ;
    

Answer 2

[Ameer Hamza]

Here is one way

A = [
    0.2000    0.0002    2.6129    2.8161
    0.2500    0.0002    2.7047    2.9356
    0.3000    0.0002    2.7897    3.0463
    0.3500    0.0002    2.8727    3.1542
    0.4000    0.0003    2.9555    3.2613
    0.5000    0.0003    3.1234    3.4770
       NaN       NaN       NaN       NaN
       NaN       NaN       NaN       NaN
    0.2000    0.0001    2.6027    2.8030
    0.2500    0.0002    2.6989    2.9279
    0.3000    0.0002    2.7857    3.0409
    0.3500    0.0002    2.8697    3.1501
    0.4000    0.0002    2.9531    3.2581
    0.5000    0.0003    3.1218    3.4748]*1e3;

idx = ~all(isnan(A),2);
idx2 = cumsum([1; diff(idx)]>0).*idx;
A_split = splitapply(@(x) {x}, A(idx,:), idx2(idx));

Result

>> A_split{1}
ans =
   1.0e+03 *
    0.2000    0.0002    2.6129    2.8161
    0.2500    0.0002    2.7047    2.9356
    0.3000    0.0002    2.7897    3.0463
    0.3500    0.0002    2.8727    3.1542
    0.4000    0.0003    2.9555    3.2613
    0.5000    0.0003    3.1234    3.4770
>> A_split{2}
ans =
   1.0e+03 *
    0.2000    0.0001    2.6027    2.8030
    0.2500    0.0002    2.6989    2.9279
    0.3000    0.0002    2.7857    3.0409
    0.3500    0.0002    2.8697    3.1501
    0.4000    0.0002    2.9531    3.2581
    0.5000    0.0003    3.1218    3.4748