If no contributions were made to my 401k account during the marriage, does my ex receive any portion?

It depends upon whether the 401k proceeds were pre-marital or separate assets acquired before the marriage (typically those are not subject to claim) or where they acquired during the marriage (which are marital assets subject to distribution). Also the length of the marriage will have a bearing.

Generally not but that is for a court to decide.

As a baseline, your spouse would be entitled to 50% of any increase in the value of your 401k during the the period of the marriage. If you had no increase, she would not be entitled to any of it. This, however, is based on a relatively short marriage, and no additional information. There could be extenuating circumstances like a long marriage, fault on your part, a disability or inability to earn a living on her part, etc. But, generally, and barring the circumstances set forth above, in a short marriage, the parties walk away with what they brought into the marriage, and one half of any assets accumulated during the marriage.

If the 401(k) accumulated no value, nor contributions, during the marriage, AND if the loans were taken out before the marriage and were not associated with any "marital debt," then your ex should likely not receive anything.

If you were repaying loans they were actually contributions, in addition your ex is entitled to share in the increase in the value of the account during marriage.